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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
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Publication Number: FHWA-HRT-04-044 Date: February 2004 |
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The focus of the literature review was to locate references discussing cost/benefits of concrete pavement design features. The basis for the current project reference list was a previously conducted literature review completed for the FHWA/NHI training course Concrete Pavement Design Details and Construction Practices. The results of that literature search focused on references that discussed pavement design features and their effects on pavement performance.
As a means of upgrading this existing reference list, additional targeted searches were completed using the TRIS, NTIS, and EI Compendex national bibliographic databases. These searches were limited to recent publications (TRIS: 1995 to 2000; NTIS: 1990 to 2000; EI Compendex: 1998 to 2000). The search identified slightly more than 100 additional records that were deemed potentially useful to the project.
After reviewing the records identified in the new literature searches, a short summary (or annotation) describing the contents of each relevant document was prepared. A final annotated bibliography was created by combining the initial results of the FHWA/NHI training course bibliography with the pertinent records found in the more recent searches.
The objective of this research study was to evaluate the performance of nine recycled concrete aggregate (RCA) design sections through both theoretical and experimental analyses. Five of these sections were 254 mm (10 in.) thick slabs of concrete pavement with varying percentages of recycled and virgin aggregates. The remaining four sections were composed of an 88.9 mm (3.5 in.) layer of hot mix asphalt (HMA) with a 12.7 mm (0.5 in.) friction wear course, over different thicknesses of RCA base material. Both types of pavements had control sections to which the test data could be compared and contrasted. For the analytical approach, the KENSLABS and KENLAYER computer programs were used to determine the stresses in the concrete slabs along with the tensile and compressive strains in the HMA sections. These parameters were then used to estimate the theoretical number of allowable repetitions for failure to occur in the individual sections. Part 1 of this report presents the results of the study of the use of RCA in rigid pavement. It includes a literature review, a review of the use of RCA in the United States, and laboratory test results. Part 2 presents the results of the study of the use of RCA as a base course in flexible pavement. It includes a literature review, a review of the state of concrete recycling in Florida, a look at aggregate properties important for base courses, and a review of international standards and U.S. Department of Transportation standards. Part 3 gives the results of the performance tests, and Part 4 the results of the theoretical analysis.
Most State paving specifications for PCC pavement allow a broad range of total aggregate gradation for concrete mixes. It has long been debated whether special efforts to control total aggregate gradation provide concrete improvements that justify potential increased costs. The results of an investigation examining the effect of optimizing total aggregate gradation on the properties of concrete used for paving in Wisconsin are reported. The investigation optimized gradations consisting of carefully selected proportions of locally available aggregate. Unit weight, shrinkage, change in the water-to-cement (w-c) ratio at constant slump, change in slump at a constant w-c ratio, compressive strength, and possible segregation under vibration were measured in field test sections and laboratory mixes. This use of optimized total aggregate gradations instead of near-gap-graded gradations in pavement resulted in an increase in compressive strength of 10 to 20 percent, reduced water demand by up to 15 percent to achieve comparable slump, air contents achieved with 20 to 30 percent reductions in air entraining agent, potentially higher spacing factors in the air void system of hardened concrete, and reduced segregation following extended vibration (1 to 3 minutes). Not all efforts at gradation optimization in this study yielded measurable improvements in performance and the availability of local aggregates may still limit, to varying degrees, the ability to optimize. However, a reasonable effort to optimize gradation can lead to significant mix benefits.
State highway agencies in Connecticut, Kansas, Minnesota, Wisconsin, and Wyoming have successfully designed and constructed rigid pavements containing recycled concrete aggregate (RCA). Success has been attributed in part to the minimization of old mortar content in the RCA during recycling processes, thereby controlling the total mortar content of the new PCC mixture, or to the achievement of higher-than-expected compressive strengths through adjustments in mix proportions, or both. There was no clear correlation between mortar content and cracking distresses in field investigations, although one project did exhibit significantly more slab cracking in the recycled pavement than in the corresponding control pavement. The increased cracking may have been due to the large differences in total mortar content between the recycled and control sections. In general, the recycled PCC pavements considered in this study have performed comparably with their conventional PCC pavement counterparts, including the recycled pavements that incorporated RCA derived from concrete affected by D-cracking and alkali-silica reactivity (ASR). There is, however, evidence of small amounts of localized recurrent ASR in the recycled Wyoming pavement. Whether this reactivity will eventually develop into widespread distress remains to be seen.
The researcher developed correlations among flexural, split tensile, and compressive strengths and ultrasonic pulse velocity from laboratory testing using materials and mix designs proposed for use in a pavement project. These relationships were used to review the current VDOT specifications and quality control procedures for concrete used in the construction of rigid pavements. Correlations between compressive and flexural strength for project-specific materials and mix designs permit the use of compressive strength cylinders rather than beams for compliance testing. The relationships also provide a means for evaluating the quality of the concrete as placed in the pavement.
When bridges and pavements are repaired or rebuilt, lane closure time should be minimized to increase safety and reduce costs and inconvenience for the traveling public. To provide a short lane closure time, special concretes are needed that attain an appropriate strength more rapidly than is possible with conventional concretes. The research reviewed in this paper demonstrates the usefulness of special concretes to provide performance and placement advantages not attainable with conventional concretes. The special concretes discussed are those containing slag, those with pozzolanic additions (silica fume or fly ash), latex-modified concrete, concretes made with Pyrament-blended cement, and portland cement with a low water-cement ratio for fast-track construction. Field applications and supporting laboratory investigations document the characteristics and superior performance levels of these special concretes.
This report reviews 11 field and laboratory studies performed to address concerns about the use of recycled concrete aggregate in pavement foundations. Performance concerns have centered on the possible impairment of drainage systems by deposits of calcium carbonate precipitate and other fines derived from the recycled concrete base materials. Environmental concerns have focused on the relatively high pH of the effluent produced by drainage systems that remove water from untreated recycled concrete aggregate foundation layers. The studies considered in this report demonstrate that all recycled concrete aggregates are capable of producing various amounts of precipitate, with the precipitate potential being directly related to the amount of freshly exposed cement mortar surface. It appears that selective grading and blending with virgin aggregates are techniques that should significantly reduce precipitate potential. One study suggests that washing recycled concrete products will reduce accumulations of crusher dust and other fines in and around the pavement drains. Others indicate that the use of filter fabrics with sufficiently high initial permittivity will allow the accumulation of precipitate and other fines without significantly impairing drainage function. This report discusses study results related to environmental concerns and provides recommendations for revisions to current specifications.
The use of accelerated cement concrete mixes in reconstruction or rehabilitation of existing highways significantly reduces lane closure times, and costs for maintenance, protection of traffic, and user delay. This study evaluated the development of two accelerated PCC mixes, which attained a compressive strength of 20.7 MPa (3000 psi) in 24 hours. These design mixes were then placed in high truck traffic pavement areas for field evaluation. The fast track concrete construction was monitored and found to be more labor intensive, but otherwise similar to the placement of normal concrete. The use of the nondestructive testing concrete maturity meter, to predict compressive strength as a function of time and performance in these projects, was a valuable quality control tool. This evaluation lasted 5 years, and the performance has been satisfactory except for initial and minor cracking. The initial cracking may have formed due to slab widths in excess of 4.27 m (14 ft) in the first project, and hairline cracking in the second site may have been caused by excessive heat of hydration. Accelerated rigid paving is recommended as a standard special provision as an alternative to class AA concrete for pavements in situations where time of closure is an important factor.
The primary goal of this research project was to evaluate the Pennsylvania Department of Transportation's (PennDOT) current concrete mixture designs for performance characteristics and provide specific recommendations on the effective use of concrete with high-performance characteristics. Highway concrete mixtures in Pennsylvania are largely designed for strengths between 23 and 31 MPa (3,300 and 4,500 psi), and for resistance to freezing and thawing. While strength and freeze-thaw resistance are important in Pennsylvania, other parameters impact the long-term performance of concrete in highway applications. Concrete can be developed to address economic considerations, as well as multiple combinations of strength, permeability, modulus, cracking tendency, abrasion resistance, freeze-thaw resistance, alkali-aggregate reaction, internal and external sulfate attack, workability, construction scheduling, traffic openings, or other criteria. The report defines high performance concrete (HPC) in the context of the PennDOT; describes the characteristics and benefits derived from the use of HPC; evaluates the current state of the practice in Pennsylvania; and identifies the performance criteria that benefit PennDOT bridges, structures, and concrete pavements. It also provides a series of recommendations for consideration for the Commonwealth of Pennsylvania.
This report documents the field performance of nine concrete pavement projects that incorporate recycled concrete aggregate (RCA) in the construction of the pavement. Multiple sections were evaluated on many of the nine projects due to perceived differences in performance levels or variations in pavement design (such as the use of virgin aggregate or the inclusion of dowel bars). All told, a total of 17 sections (of which 12 contain RCA) were subjected to an extensive field testing program consisting of pavement condition surveys, drainage surveys, FWD testing, coring, and serviceability assessments. Each of the 17 sections included in the investigation is described in detail. Performance observations and results from the FWD and laboratory testing are presented, with emphasis on evaluating the effect of RCA on pavement performance. An overall summary is provided that synthesizes the findings and conclusions of the field-testing program.
This paper focuses on optimal concrete mix design, including the determination of w/c ratio (water over cement in quantity), amount of admixtures, and grading of course aggregate for the cement concrete. Through this research, a special methodology was developed for a concrete mix design that is capable of adapting to changeable temperature, environment and climate, surface characters of the course aggregate, and concrete curing time for pavements. In addition, this paper presents new ideas in the design of concrete containing admixtures and in the study of surface characteristics of the coarse aggregate. The method is also applicable to the design of ordinary PCC.
This report covers the construction of concrete pavements and concrete bases without attempting to include inflexible specifications for procedures, materials, or equipment. References are made to specifications, but only as a guide to enable a selection of requirements suitable for a particular location or class of work. Sections are devoted to specifying, sampling, and testing materials, and to the possible influence of materials on skid resistance, economy, and durability. Subgrades and subbases are treated only as a final preparation for paving. Arrangement of joints is described, and references are given for guidance in using reinforcement. Sections on mixing, placing, finishing, and curing concrete refer to other ACI reports where pertinent, but make recommendations for the special handling requirements for pavement construction.
This technical bulletin describes the design and construction of fast-track concrete pavements. It includes a summary of appropriate applications of fast-track paving technology and also describes the planning efforts required. Considerable discussion is spent on obtaining suitable concrete material for fast-track paving projects, including the cement type and content, supplementary cementing materials, use of admixtures, and aggregate gradation and properties. Details on critical construction aspects of fast-track paving are also provided, including a description of recommended curing and temperature management procedures.
This manual accompanies a 2½ day training course on concrete pavement construction. The course material is aimed at field personnel, both contractor and agency, and is intended to provide them with a general working knowledge of field operations. Field operations presented here include central mix plant operations, ready mix plant operations, slipform paving operations, fixed-form paving operations, joint sawing and sealing operations, and concrete pavement restoration activities.
Current Australian practices in the areas of concrete curing and interlayer debonding reflect a blending of experience from leading overseas authorities together with that obtained from substantial local experience since the 1970s. Australian practices were summarized (for the wider range of design and construction issues) in a paper presented at the Fifth Purdue Conference in 1993, but significant developments have occurred since. In terms of curing practices, the major developments have been in the types of curing compounds being used (for both pavements and bases), and in the method of specifying and monitoring their quality in contracts. In the area of interlayer debonding, changes have been made to the specified materials and methods. With few exceptions, concrete pavements constructed within the past 20 years have been over a lean-mix concrete base. Ongoing experience confirms that the level of interlayer friction is critical to the early thermal movement and to joint induction. It is also critical to the avoidance of unplanned reflection cracking in the pavement and thereafter to its long-term performance. Particular attention has been focused on refining debonding treatments under continuously reinforced pavement following experience on several projects, which exhibited undesirable cracking patterns that were thought to have been largely a consequence of too high a level of interlayer friction. This paper discusses the Australian specifications and practices in these areas. Comparison is also made to the international experience as reflected in the published literature, and a brief account is provided of current ongoing development work in this field. A brief discussion of factors (additional to interlayer friction) that appear to influence cracking patterns in continuously reinforced concrete pavements is provided.
To meet the need of transportation authorities, accelerated methods for constructing concrete pavements have been developed. These techniques, called fast-track concrete paving, have been developed through several years with experience gained on many projects. Fast-track concrete paving requires changes to traditional construction specifications and processes. In addition to material modifications, changes in worker responsibilities, construction staging, pavement joint construction, and opening-to-traffic criteria can be made to accelerate a concrete paving project.
To meet the need of transportation authorities, accelerated methods for constructing concrete pavements have been developed. These techniques, called fast-track concrete paving have been developed through several years with experience gained on many projects. Fast-track often uses conventional concrete paving materials and processes, but key changes can significantly accelerate construction. These key components include material modifications, and changes in worker responsibilities, construction staging, pavement joint construction, and opening-to-traffic criteria that can be made to accelerate a concrete paving project.
Field tests at have proved that the temperature development in concrete immediately after paving is of great importance on slab curling. Placing the concrete on warm, sunny days causes an upward curling due to a zero-stress temperature differential through the slab. That is, the no-curl condition (flat slab) is not reached at a zero temperature differential, but rather at a high positive temperature gradient. This construction-induced curling can have a significant effect on pavement performance. Wet curling lowers the zero-stress temperature at the surface and counteracts this upward curling.
Concerns over concrete roadways exhibiting distress at ages earlier than expected led to the initiation of a study to examine several concrete pavements located throughout the Midwest. The goals were to reach a consensus as to the mechanisms of the distress and to recommend corrective actions to prevent future occurrences until additional research could be conducted. Primary materials-related distress mechanisms identified include freeze-thaw deterioration, sulfate attack, ASR, and alkali-carbonate reactivity. Primary construction related distresses include poor consolidation and material segregation. Specific recommendations include advice on returning to the basic methods of concrete construction and avoiding the use of materials known to contribute to early distress.
Grove, J. D. and K. B. Jones. 1996. Fast Track Basics. Materials for the New Millennium Proceedings of the Materials Engineering Conference. Volume 1. American Society of Civil Engineers, New York, NY.
Fast track PCC paving is a concept, not merely a concrete mixture. There are four major aspects that in combination, achieve rapid strength gain and early opening time: cement type, cement content, curing method, and opening strength criteria each must be considered. The actual time of opening can now be designed to match the requirements of a project or portion of a project. Because early strength comes with a cost, to use only those elements that are needed to meet the project requirements will allow the most economical solution and still achieve the desired goals. Fast track concrete can be designed to achieve opening strength in less than 6 hours, 2 or more days, or almost anything in between. This paper discusses the various aspects of fast track concrete paving and offers some examples of opening times based on various combinations of the elements.
The fast-track or high early-strength concrete offers the opportunity of taking advantage of higher early strength gain in a smaller time for construction or rehabilitation of high-volume roads and city streets serving businesses. A section of fast-track concrete pavement built in an urban setting in Manhattan, KS, had mixture design developed using a special Type-III cement and three different types of locally available aggregates. A recent visual survey indicates that the longitudinal surface texture of the pavement is showing wear. This might have been due to the grinding action of the sand particles on the pavement surface applied during the winter months under the traffic load. Overall, the performance of this pavement is excellent.
Six jointed reinforced concrete pavement and one jointed plain concrete pavement test sections on US 69 in Miami County, KS, and constructed in 1979 have been surveyed annually for faulting for the past 9 years. FWD tests were conducted in 1995 to assess the load transfer efficiency of the joints. The results show that, in general, as the original concrete density increases due to improved consolidation, the rate of increase of the joint fault depth decreases at doweled joints at a given pavement age. The occurrence of joint faulting is much more severe when load transfer devices are not present; this was observed even for the pavement section built on a nonerodible subbase. Improved consolidation sometimes appears to help improve load transfer, resulting in a lower rate of faulting. Thus, the mandatory density requirement of 98 percent rodded unit weight, which has been in effect since 1980, has undoubtedly led to better joint performance for concrete pavements in Kansas.
This paper presents recommendations for high performance concrete paving practice drawn from 20 years of designing and monitoring the performance of continuously reinforced concrete (CRC) pavements in Texas. Performance indicators used include crack spacing distribution, crack width, crack randomness, delamination spalling, and vertical distribution of tensile strength. Variables studied include aggregate type (limestone or siliceous gravel), aggregate blending, placement season, placement time of day, placement above 32 ºC (90 ºF), use of crack initiators, use of skewed transverse steel, evaporation rate, percent steel reinforcement, and steel bar diameter. The variables studied are ranked in the order they affected performance to identify which are significant and can be controlled in the design and construction phases.
This research focuses on modeling early-age behavior of both concrete pavements and bonded concrete overlays (BCOs) subjected to stresses from moisture and thermal changes. It includes the development of a two-part, versatile, comprehensive set of guidelines that provide direction in the proper selection of design and construction variables to minimize early-age damage to the PCC pavement and BCO. The first part of these guidelines is qualitative in nature and is based upon the results of this effort, past experience, and engineering judgment. The guidelines are intended to identify design and construction inputs that are most likely to lead to good behavior during the early-age period.
This research focuses on modeling early-age behavior of both concrete pavements and BCOs subjected to stresses from moisture and thermal changes. It includes the development of a two-part, versatile, comprehensive set of guidelines that provide direction in the proper selection of design and construction variables to minimize early-age damage to the PCC pavement and BCO. The first part of these guidelines is qualitative in nature and is based upon the results of this effort, past experience, and engineering judgment, and intended to identify design and construction inputs that are most likely to lead to good behavior during the early-age period. The end product from this research is a comprehensive software package termed HIgh PERformance PAVing (HIPERPAV). This package, which incorporates the complex models developed, can be used as a stand-alone product to verify the overall effect of specific combinations of design, construction, and environmental inputs on early-age behavior of a PCC pavement and BCO.
Technology for fast-cure concrete, used in other construction areas in the past, recently found application in highway pavement. During July 1986, a 10-cm (4-inch) concrete overlay was applied to 11.2 km (7 mi) of U.S. Highway 71 north of Storm Lake, IA. The project team developed a new type of concrete mix that cures fast to allow traffic onto the road in only 24 hours. This innovation provides an example of cooperative government-industry effort and successful procurement policies implemented by a government agency. Initiated as a response to competition from other materials, the development of fast-track concrete illustrates the process and involvement of many organizations in product innovation. This paper describes the development of paving technologies in Iowa, the formation of an industry association, and the innovation process to bring about technical improvements and cost competitiveness. The implications section describes elements of government policy to foster an increased rate of innovation in U.S. public construction (including supporting increased technical capability) using demonstration projects and encouraging competing technologies.
A study with the objectives of providing guidelines for (1) timing of contraction joint sawcutting to avert uncontrolled pavement cracking and (2) early loading of pavements by construction traffic has been conducted. This volume presents the results of the research. A laboratory study of early age (4 to 24 hours) and early pavement loading (1 to 28 days) concrete strength properties for a range of highway concrete mixes was made. Sawcutting tests were made to determine earliest contraction joint sawcutting. Earliest sawcut timing was correlated on the basis of sawcut ratings to concrete strength properties and nondestructive test results that can be used for determining earliest sawcutting time. The latest sawcutting time was targeted on the basis of buildup of restraint stresses attributable to slab cooling. Concrete pavement placement and joint sawcutting were observed at three highway construction sites to verify test results. Guidelines for sawcut timing are presented to facilitate construction site decision-making based on nondestructive test methods. Early loading by construction traffic was analyzed using the ILLI-SLAB finite element program, and guidelines developed for assessing damage done by early loading.
This volume presents supporting documentation for the research study described in item 16, including a summary of early age (4 to 24 hours) laboratory test data, a summary of early age (1 to 28 days) laboratory test data, a summary of the laboratory sawing strip data, a compilation of the field joint sawcutting data, a summary of the field load testing data, and the state-of-the-art review of concrete sawcutting activities.
This report discusses the relative merits of Texas specifications (Tex-219-F) and ASTM specifications (ASTM C 156-80) for the testing of moisture retention by liquid membrane-forming curing compounds. Preliminary work toward the development of a new moisture retention test to replace Tex-219-F and/or ASTM C 156-80 is also outlined, in addition to suggestions for continuing research in this direction. Recommendations are presented with regard to the 6-month curing compound shelf life in effect at the time of the study and the possibility of extending this shelf life. Research is also reported dealing with the effects of altering application rates and patterns on moisture retention. Finally, the use of optical reflectance as a measure of application rate is examined.
This is an addendum to the User's Manual of the comprehensive software package termed HIPERPAV. This package, which incorporated the complex models developed, can be used as a stand-alone product to verify the overall effect of specific combinations of design, construction, and environmental inputs on early-age behavior of a PCC pavement and BCO. This report provides color illustrations and an update of information in the User's Manual.
Spalling is a form of distress in concrete pavements. However, the current state of knowledge and the available prediction models on spalling indicate a lack of understanding of the spalling mechanism. This research attempts to fill the need to develop a framework to incorporate spalling in the design of concrete pavements based on a mechanistic approach. The report presents results from a comprehensive field survey on spalling in concrete pavements in Texas. Based on the results from this field survey, a mechanism for spalling is proposed. According to this mechanism, spalling is the culmination of damage initiated as delaminations early in the life of pavements. The development of delaminations is related to the concrete mix design and conditions at the time of paving, including ambient conditions and the method of curing. The delaminations are extended into spalls as a result of fatigue damage induced by traffic and temperature fluctuations in the pavement. Early-age analysis of concrete pavements wasperformed using a finite element program developed to predict stresses in the pavement caused by shrinkage. Results from the analysis indicated that a high level of stress sufficient to create delaminations might be generated at a very early age. The coarse aggregate type in concrete was noted to have a significant effect on the level of spalling. Based on results from laboratory studies, a mechanism on how the aggregate type influences spalling is proposed. This proposed spalling mechanism is included in a framework to incorporate spalling in the design of concrete pavements.
PCC pavement of especially high quality became an area of interest in the early 1990s and precipitated a tour by representatives of industry and government to observe European construction practices. Following the tour, the FHWA developed a research program to encourage and aid States in constructing high-performance concrete pavement.
The design and construction of PCC pavement involves the selection, specification, and construction of a number of concrete pavement features that can significantly affect pavement construction costs. In this study, the relative effect on pavement construction cost of several concrete pavement features was investigated, including concrete pavement thickness, foundation, shoulders, cross section thickness variation (trapezoidal section), joint spacing, transverse joint load transfer, and transverse joint sealant. Careful consideration and study should be given the cost effects of various features when designing and specifying concrete pavement. The ideal pavement design is one that selects the least costly pavement section that will perform to the expected level over the life of the facility. The least costly pavement section is that with the least life-cycle costs.
This participant's notebook was developed by FHWA staff to compliment a 2-day workshop on life-cycle cost analysis (LCCA) in pavement design. This workshop will be of interest to State highway agency personnel responsible for conducting and/or reviewing pavement design LCCAs. The FHWA Office of Engineering, Pavement Division, in cooperation with the Office of Technology Applications, offers LCCA technical support through Demonstration Project No. 115, "Probabilistic LCCA in Pavement Design" (DP-115). DP-115 is a free 2-day workshop that demonstrates best practices in performing LCCAs for pavement design. This workshop is available, upon request, to State highway agencies. The participant's notebook is presented in 13 modules and a set of class exercises (with solutions).
This report provides an outline for the engineer seeking to conduct a LCCA in pavement design and selection. The guidance, recommendations, and default values provided here were collected from 10 years of paving projects. Most of these projects were constructed or rehabilitated in the mid-1980s in order to evaluate the current design and construction practices in Colorado. At this time, the Colorado DOT uses a deterministic approach to the LCCA and is researching the move toward a probabilistic LCCA.
The paper describes some features of the vehicle operating cost/road-roughness relationships reported in major international research studies from 1972 to 1986. This research is characterized by the use of road-surface roughness devices, fleets of experimental vehicles to measure fuel consumption, large-scale surveys of vehicle operators, improvements to modeling speed and fuel, and the development of user-friendly economic evaluation models. All studies report significant effects on operating costs following changes in surface roughness. The issues of calibration, new vehicle technologies, and extrapolation of study results are then discussed. The paper concludes by characterizing the main features of the research studies and shows the rise in operating costs attendant on allowing surface conditions from deteriorating to high levels of roughness.
The true value of any pavement is determined by factors such as quality, initial cost and cost of upkeep, service life, and quality of service life. The choice between pavement types of equivalent design is based not solely on initial cost, but is almost always dependent on subsequent costs and length of service life. Thus, recent information and references on these topics were summarized and are presented here.
Whole-life costs (WLC), or life-cycle costs, of a road pavement are understood to represent the costs incurred during the lifetime of a road and may include costs to the road administration from planning the road to its full replacement. In practice, however, WLC are limited to the costs incurred by construction and maintenance of the road over a specified period. The contents of this report are as follows: (1) Background; (2) Introduction; (3) Costs; (4) Functions; (5) Material Characteristics; (6) Road Deterioration Models; (7) Whole-Life Costing; (8) Value of Tied Up Capital/Interest Rate; (9) Probabilistic Approaches; (10) The Use of WLC Models, Examples; (11) Future Development; and (12) Conclusions.
This bulletin recommends procedures for conducting LCCA of pavements, provides detailed procedures to determine work zone user costs, and introduces a probabilistic approach to account for the uncertainty associated with LCCA inputs. The bulletin begins with a discussion of the broad fundamental principles involved in an LCCA. It discusses input parameters and presents simple examples of traditional LCCA in a pavement design setting. It discusses the variability and inherent uncertainty associated with input parameters, and provides recommendation on acceptable ranges for the value of time as well as discount rates. It explores the use of sensitivity analysis in traditional LCCA approaches. User costs are a combination of delay, vehicle operating costs, and crash costs. Each of these cost components is explored and procedures are presented to determine their value. Given the power and sophistication of today's computers and software, simulation techniques (such as Monte Carlo) are recommended for incorporating variability associated with LCCA inputs into final results.
The current pavement selection policy of WisDOT limits the design alternatives for PCC pavements and inhibits the designer's ability to select cross sections deviating from uniform slab thickness with doweled transverse joints. Currently, uniform slab thicknesses and conventional joint load transfer devices are incorporated into the design based on the heavy truck traffic in the outer lane. While this strategy provides for adequate pavement structure in this truck lane to limit faulting and slab cracking to tolerable levels, there is a potential for over-design in other traffic lanes, which receive significantly lower ESAL applications over the service life of the pavement.
This paper begins by examining the lateral and longitudinal distribution of traffic loading applied to highway pavements. The effects of crossfall, superelevation, lane distribution, direction, longitudinal profile, acceleration, and deceleration are considered. A tapered cross section is proposed as the most appropriate design to achieve the best value for money. Following a desk-top study, the author, in collaboration with Lancashire County Council, designed and constructed a full-scale trial on the A584 road bypassing Freckleton village. This was to be the first tapered section pavement in the UK. There were three conventional control sections and three corresponding tapered sections. Following deflectograph and impulse radar surveys, it was shown that it was possible to double the design life for a pavement by redistributing the base material to form a tapered section at no extra cost.
This document presents the current AASHTO procedures for the design of flexible and rigid pavement structures. It contains the major revisions to the AASHTO new pavement design procedure that were adopted in 1986 and which incorporate such new elements as design reliability, subgrade resilient modulus, environmental considerations, drainage provisions, life-cycle costing, low volume road design, pavement management concepts, and rehabilitation guidelines. New pavement overlay design procedures adopted in 1993 are also contained in the guide.
This supplement to the 1993 AASHTO Design Guide includes alternative design procedures that can be used in place of or in conjunction with Part II, Section 3.2 "Rigid Joint Design" and Section 3.3 "Rigid Pavement Joint Design." The development of these alternative design procedures was initiated under National Cooperative Highway Research Program (NCHRP) Project 1-30 and continued under an FHWA-sponsored study using LTPP performance data. Improved guidance on the selection of appropriate k-value for use in design, a rederived performance model representative of critical loading conditions and incorporating joint spacing and associated curling, and improved guidelines on joint design details are found in the new procedure. A detailed example is provided, along with recommended design faulting check for doweled and nondoweled pavements.
This report presents the early results of the Specific Pavement Study (SPS)-2 experiment, "Strategic Study of Structural Factors for Rigid Pavements" documenting construction details of 13 different test sections with varying structural characteristics. The SPS-2 experiment was developed as a coordinated national experiment to address the effects of various strategic environmental and structural factors on the performance of rigid pavements. The factors studied under this experiment included concrete thickness, concrete strength, base type, lane width, drainage and environmental factors such as temperature, moisture and soil type. This paper discusses the performance of these test sections after being in service for 4 years. The results are based on monitoring data collected by the LTPP.
This paper discusses several aspects of concrete pavement design and construction and their relationship to performance, with emphasis on the effects of temperature displacements on performance of pavement slabs. Experience with concrete pavements in Florida indicates that doweled joints perform better than undoweled joints, skewed transverse joints did not demonstrate advantages over perpendicular joints, slab lengths between 4.6 and 5.5 m (15 and 18 ft) experienced less cracking, joint sealing is beneficial but is not a substitute for good drainage, preformed compression sealants last considerably longer than silicone or other joint sealing materials, slab widening reduces cracking, the optimal base stiffness is one that provides a k value between about 5.4 and 10.9 MPa/m (200 and 400 pci) (lower k values resulting in higher load-related slab stresses, and higher k values resulting in higher curling-related slab stresses), water curing is preferable to curing compound and blanket curing in terms of moisture retention and temperature control, and joints should be sawed within 1.5 hours of slab finishing (sooner in hot weather and/or in accelerated paving).
Since 1975, the Roads and Traffic Authority of New South Wales has promoted the increased use of concrete pavements throughout the State. Approximately 1300 lane-km of concrete pavement had been constructed as of mid-1993. The Australian industry expanded rapidly in an environment that is geographically remote from overseas areas of long-standing experience such as the United States and western Europe. The adoption of this relatively new technology in the Australian context attracted close attention from both the media and the traveling public. It has therefore been a major priority to implement and refine good design and construction practices as rapidly as possible. Current Australian practice reflects a blending of local experience with that from leading overseas authorities. This paper summarizes local developments in Australian concrete pavement technology since the mid-1970s. Recent indications point to a likely growth in concrete pavement construction throughout the southeast Asian region, and recent Australian experience would appear to be relevant.
In 1993, New York published a new Thickness Design Manual for New and Reconstructed Pavements based on the 1986 AASHTO Design Guide. The AASHTO equation for rigid pavement performance was calibrated with performance data for 225-mm rigid pavements in New York, and the calibrated equation was then used to design rigid pavements. Because New York does not have experience with thicknesses greater than 225 mm, the modified AASHTO equation could not be verified for thicker pavements. The development of a mechanistic-empirical (M-E) design procedure for verifying the designs presented in the new thickness manual is described in this paper. First, a nondimensional fatigue model was established on the basis of New York's past pavement performance, environmental conditions, and traffic loadings. The study was then extended to develop design curves for thicknesses of 225, 250, 275, 300, and 325 mm (9, 10, 11, 12, and 13 inches) (5-m (15-ft) slab lengths for 225- to 275-mm (9- to 11-inch) thicknesses and 5.5-m (18-ft) slab lengths for 300- to 325-mm (12- to 13-inch) thicknesses). Finally, the M-E design curve was compared with the modified AASHTO equation. The results indicate that for thicknesses greater than 275 mm (11 inches), AASHTO predicts up to 40 percent more equivalent single-axle loads than the M-E approach.
Current pavement design procedures are based principally on empirical approaches. The current trend toward developing more mechanistic-empirical pavement design methods led Minnesota to develop the Minnesota Road Research Project (Mn/ROAD), a long-term pavement testing facility. The project consists of 40 heavily instrumented test sections, 14 of which are jointed plain concrete (JPC) designs. Mn/ROAD researchers determine the predicted lives of the concrete test sections by applying design and as-built data to three currently accepted concrete pavement design methods: Minnesota Department of Transportation's rigid pavement design guidelines; AASHTO Guide for Design of Pavement Structures 1993; and the Portland Cement Association (PCA) Thickness Design for Concrete Highway and Street Pavements (1984). The analysis began with determining the applicable as-built parameter values for each respective design method. Applying the as-built parameters to the three methods resulted in widely varied predictions of pavement life. For the 1993 AASHTO design method, reliability levels of 50 percent and 95 percent were applied for comparison. An experimental procedure for converting PCA method fatigue and erosion results to AASHTO type CESALs (concrete pavement equivalent single axle loads) demonstrated unsuitability. Validation of the predictions presented will occur as the test cells reach their terminal serviceability.
This document implements changes to the current design guidance contained in Chapter 600 of the California Highway Design Manual for PCCP on the state highway system. Major changes contained in the bulletin include the use of lean concrete bases for heavy traffic volumes, the use of perpendicular joints while maintaining variable joint spacing of 3.6, 4.6, 4.0, and 4.3 m (12, 15, 13, and 14 ft), the use of tied and sealed longitudinal joints, the use of epoxy-coated dowel bars at transverse joints, and tied concrete shoulders of the same structural thickness as the mainline pavement.
The paper compares the performance of concrete pavements of two stretches of autoroute, the Albacete and La Roda bypasses, located in central Spain. Both pavements can be considered carbon copies of each other because they are close to each other; they are almost the same age; they support almost the same amount of traffic; and they share the same project features. The most significant difference is the length of the concrete slabs: between 3.7 and 5 meters (12 and 16 feet) for the slabs on the Albacete and 3.4 and 4.5 meters (11 and 14.7 feet) for La Roda. This major separation of joints may explain the very different performance of each stretch of road; whereas the Albacete segment has over 25-percent cracked slabs, the figure for La Roda is 6 percent.
New York's effort in adapting concepts from AASHTO's pavement design guide as a basis for a revised state design procedure for thickness of new and reconstructed pavements is summarized. The rationale for this revised procedure was to design more durable pavements and reduce life-cycle costs. New York's past pavement design practice and the background for the revisions are briefly described. A sensitivity analysis was conducted to identify how AASHTO design variables affect pavement thickness. Past performance of selected New York pavements was also studied. The rationale is discussed for determination of appropriate design variables, based on the sensitivity analysis, performance studies, and reviews of past and current practice. Also described is the justification of other design features, such as 50-year design life, granular subgrade, permeable base, edge drains, shorter slabs, maximum and minimum pavement thicknesses, and new dowel and tiebar designs. Development and implementation of New York's new AASHTO-based thickness design procedure are major steps toward accomplishing the goals of building longer lasting pavements and reducing life-cycle costs.
The effect of coarse aggregate on pavement performance has been attributed to the volume of aggregate used in pavement construction. The different patterns of crack development for limestone (LS) and siliceous river gravel (SRG) are a typical example of aggregate-induced variable performance in continuously reinforced concrete pavement (CRCP). Laboratory and field testing was conducted to evaluate these aggregate types for suitability in CRCP construction. CRCP sections constructed with LS aggregates displayed better performance than those containing SRG. Surprisingly, CRCP sections containing an LS-SRG blend showed worse performance than did those containing SRG only.
This book presents a comprehensive look at the design, construction, and performance of pavements. It examines the principles of pavement design and describes in detail the critical data needed for a reliable pavement design: materials characterization, traffic estimation, climatic factors, and geological and subgrade parameters. Drawing upon experimental roads constructed in both the United States and in Great Britain, it presents valuable information on the performance of different pavement designs under different traffic and environmental loading. Finally, current design procedures for both flexible and rigid pavements are presented, along with descriptions of the movement toward more mechanistic-based procedures.
The current pavement design and selection process of the Wisconsin Department of Transportation (WisDOT) for all new pavements or reconstructions of existing pavement structures provides for the design of one asphaltic concrete (AC) and one portland cement concrete (PCC) pavement alternative. Life-cycle cost analyses are then used to determine the preferred alternative for construction. Previous restrictions in the WisDOT pavement selection process have essentially excluded the construction of thick AC (AC thickness > 150 mm (6 inch)) and thin PCC (PCC thickness < 225 mm (9 inch)) pavements and thus the validity of current life-cycle cost inputs for these pavement types is questionable. This report presents a performance analysis of existing thick AC and thin PCC pavements constructed in and around Wisconsin. The performance trends developed indicate that current design assumptions utilized by WisDOT and related to the expected service life to first rehabilitation of AC and PCC pavements may also be used for thick AC and thin PCC pavements.
Comprehensive procedures for the structural design of "zero-maintenance" JPCP for heavily trafficked roadways are presented. The term "zero-maintenance" refers to the structural adequacy of the pavement lanes and shoulder. The design procedures are based upon results from long-term field studies, comprehensive mechanistic analyses, and laboratory studies, the basis for which is provided in this report. Both a serviceability-performance analysis and a concrete fatigue analysis are used in the structural design, and additional procedures are included for the design of the subbase, shoulders, joints, and subsurface drainage. Example designs are included with sensitivity and incremental cost analyses.
This is an engineering guide for the design of heavily trafficked JPCP to provide "zero-maintenance" performance over the selected design period. Procedures are included for designing the concrete slab, subbase, shoulders, joints, and subsurface drainage. A computer program (JCP-1) is used to provide serviceability-performance and fatigue data for the structural design of the pavement. The manual includes specific recommendations for obtaining all necessary inputs and for performing the structural design. A detailed design example for a heavily trafficked freeway pavement is provided, including a sensitivity analysis of major design factors.
The development of design procedures for heavily trafficked plain jointed concrete pavements to provide "zero-maintenance" performance is described. "Zero-maintenance" refers only to structural maintenance, such as patching, crack repair, slab replacement, grinding of faults, and overlay. Procedures are included for designing the concrete slab, subbase, shoulders, joints, and subsurface drainage. A computer program (JCP-1) was used to provide serviceability/performance and fatigue data for the structural design of the pavement. These procedures were developed based on nationwide field studies, long-term pavement performance data from in-service pavements, mechanistic analyses, and laboratory studies. A detailed design example for a heavily trafficked freeway pavement is presented, along with a sensitivity analysis of the major design factors.
This report describes the development of COPES, which provides a framework and procedures for the systematic collection of historical and field data on the characteristics and performance of in-service PCCP. The first part of the report provides a summary of the development of COPES and demonstrates the potential uses of the data collected under COPES. Data collected from six States were analyzed to illustrate the impact of design features and construction practices on concrete pavement performance. The analyses took the form of regression equations, which, although intended for demonstration purposes, provide insight into the performance of concrete pavements. Detailed appendices present a comprehensive COPES user's manual and the results of the case studies conducted in the six States.
The AASHTO design guide's rigid pavement equation that is used for thickness design was originally developed in 1960 at the conclusion of the AASHO Road Test. This equation predicts the number of axle loads for a given slab thickness and loss in serviceability. During the past 30 years, the original equation has been extended to include several additional design factors and has been used by many highway agencies for rigid pavement design. Due to the limited inference space of the original road test equation and the subjective nature of the subsequent extensions, there is considerable interest in determining the adequacy of the equation. The availability of the nationwide LTPP data has finally made an overall evaluation possible. The evaluation included determining the adequacy of predicting the number of heavy axle loads required to cause a given loss in serviceability. The results indicate that the original 1960 equation generally overpredicts the number of 18-kip equivalent single-axle load applications for a given loss of serviceability. However, extensions to the original model improve predictions considerably. These results were determined at the 50th percentile. At a higher level of reliability (such as 95 percent), the 1986 AASHTO model provides a conservative design for a majority of the pavement sections. However, several deficiencies remain in the model.
Field-calibrated, mechanistic-empirical models have been developed for key performance indicators of jointed concrete pavements. Performance data from nearly 500 inservice pavements were used along with mechanistic and empirical variables to develop improved prediction models for joint faulting, slab cracking, joint spalling, and current serviceability rating. The models should prove valuable in checking the performance capabilities of various pavement designs determined by other means and in determining the relative impact of different design variables on concrete pavement performance.
Following the example of design catalog development by several European countries, this study's major product is the catalog of "good practice" recommendations for design features of highway pavements. Design cells are defined by three main "site conditions": traffic loadings, subgrade support, and climate. Within each cell, recommendations are given for the pavement type, layer thicknesses, materials, joint design, reinforcement design, drainage design, and other features related to performance. The document is not intended for use as a pavement design manual or for project-level pavement design.
A methodology was developed for estimating the remaining life of a nonoverlaid continuously reinforced concrete pavement. The models presented use several key predictors: the early-age crack distribution pattern in the concrete caused by volumetric changes, the coarse aggregate type used, and the presence or absence of a swelling subgrade that will accelerate the rate of failure development in later life due to dynamic loadings. Considering these factors, the models can accurately estimate the additional 18-kip ESALs that will take the pavement from its current condition in terms of failures per mile to a user-defined "failure threshold. Using traffic models developed in another study, the number of additional ESALs to failure can be translated into time to failure for planning purposes.
In the simplified calculation method (slab structure replaced by beam on a rigid support) presented in this paper, the moment due to surface shrinkage is compared with the fictitious equivalent moment caused by a linear negative temperature gradient. This analogy allows the prediction of the critical slab length for which the point support at the slab center changes to continuous support with rising slab length, caused by increasing dead weight of the slab. Then the upward shrinkage curling can be calculated using the well-known equations for curling due to a linear temperature gradient, in which the fictitious gradient is replaced by terms derived from the mentioned analogy. Results calculated for different slab thicknesses agree reasonably well with in situ curling measurements on young concrete slabs. Upward curling due to shrinkage can be reduced gradually by increasing slab thickness.
This manual presents design considerations for concrete pavements. It describes initial considerations in the pavement design process, including subgrade characterization, paving materials characterization, traffic loading considerations, drainage design elements, and design reliability. It presents the AASHTO rigid pavement design procedure and follows up with an introduction to mechanistic-based design concepts. It also presents recommendations on rigid pavement design features. The manual concludes with a summary of overlay rehabilitation methods for rigid pavements.
This Technical Advisory outlines recommended practices for the design, construction, and repair of continuously reinforced concrete pavements. It gives recommendations on longitudinal steel reinforcing requirements (including bar sizes, location, placement), base and subbase requirements, joint design guidelines (construction joints, longitudinal joints, terminal joints), and on construction and placement activities.
The U.S. TECH Study Tour traveled in France, Austria, Germany, the Netherlands, and Belgium, and heard presentations from Spain, Portugal, Switzerland, and Italy. Concrete pavements are built for heavier loads and longer lives (30 to 40 years) than in the United States. The slab thicknesses generally do not exceed those constructed in the United States. Other design features such as widened slabs, trapezoidal cross sections, thick granular subbases, and highly durable concrete mixes are used to achieve longer performance lives. High population densities make tire/road noise an important environmental issue in Europe; considerable research in development of noise-reducing finishes and textures has been done in several countries. Other European concrete pavement technology advancements recommended by the study tour group for consideration in the United States are warranties for pavement construction, greater cooperation between government and industry in research and development, innovative toll-road financing, and the use of pavement design catalogs.
This course notebook presents the design procedures found in AASHTO's 1993 Guide for Design of Pavement Structures. It describes the basis for both the flexible and rigid pavement design procedures, including the assumptions and limitations inherent in each approach. Considerable guidance is provided on developing appropriate inputs for use in the development of pavement designs. Additional design elements are also described for each pavement type, such as layer thickness determination for flexible pavements, and steel and joint design for rigid pavements.
This course notebook presents a broad overview on pavement design and analysis procedures. Commonly used design procedures are presented for both flexible and rigid pavements, including AASHTO, Asphalt Institute, and PCA. Basic pavement responses (stresses, strains, and deflections) are also described, and various pavement analysis models and performance prediction models are introduced for both flexible and rigid pavements. The emphasis of the information is on checking the reasonableness of resulting pavement design, with the goal of obtaining reliable, long-lasting pavement designs.
This LTPP data analysis was intended to examine, in a practical way, the LTPP database and to identify the site conditions and design features that significantly affect transverse joint faulting. Key products developed as part of this research were (1) answers to frequently asked questions regarding design features and site conditions that lead to "good" (better than expected) and "poor" (worse than expected) performance of jointed concrete pavements relative to joint faulting and (2) guidelines to assist highway agencies on what works and what does not work in the design of transverse joints to control joint faulting. This TechBrief presents key findings of this research.
The LTPP analysis program has addressed a broad array of topics-from field validation of pavement design procedures, to the study of variability in traffic and materials data, to investigating pothole repair techniques. The purpose of this document is to highlight some of the key findings from LTPP analysis studies between 1990 and 1999. These findings have been organized into the following areas: site conditions, structural features, materials, initial roughness, pavement maintenance, pavement rehabilitation, AASHTO design validation, and performance modeling.
The structural design of flexible and rigid pavements has evolved from the application of engineering judgment to include a variety of processes. This report describes the various methods for structural pavement design in the United States and in several Canadian provinces. It focuses on the elements intended to provide strength and stiffness to the pavement. It includes a summary of current practice and trends in the design of new pavements and overlays for several elements, including thickness design procedures, layer compositions, drainage treatments, characteristics of materials, mitigation of swelling and frost heave, and assessment of pavement residual strength and condition for overlay design.
Environmental effects and repetitive traffic applications can produce transverse cracks in jointed concrete pavements. Maintaining adequate aggregate interlock load transfer across these cracks is essential to preserving the functional and structural integrity of these pavements. The objectives of this study were to determine the design parameters that significantly affect transverse cracking and to demonstrate methods available for evaluating cracked pavements. Field data collected from in-service jointed concrete pavements located throughout southern Michigan were used to accomplish these objectives. Joint spacing, coarse aggregate type, shoulder type, and pavement temperature were found to have significant effects on transverse crack development and/or performance. The surface texture of crack faces was assessed using a promising new test method called volumetric surface texture testing. Volumetric surface texture results provided an indication of the aggregate interlock potential of pavements containing various aggregate types. Three performance parameters capable of mechanistically characterizing crack performance were discussed. A relatively simple procedure was described for determining these parameters and evaluating crack conditions. Field data were also used to demonstrate and validate a voids' analysis procedure. This procedure estimates the potential for loss of support near cracks and joints, thus allowing for proper rehabilitation actions before the manifestation of additional distresses.
This study evaluates the special features of premium design guidelines―features not considered in the AASHTO flexible and rigid pavement design procedures. The significance of these features (15 in all for 4 pavement types) was investigated by evaluating pavement performance and design reliability. The researchers used the VESYS III program to evaluate features of the flexible pavements and an algorithm developed in a companion paper for the other three types (composite, jointed plain concrete, and continuously reinforced concrete). This computer program, Reliability Analysis and Performance of Pavements I (RAPP-I), employs Monte Carlo simulation techniques to treat all the design variables probabilistically. The effectiveness of each feature is evaluated by comparing the performance or expected life and reliability of typical pavement sections with and without a premium feature.
This paper reviews the design and performance of continuously reinforced concrete pavement (CRCP) in Illinois, which has built more than 4,267 two-lane km (2,650 miles) of CRCP on the Interstate system since the mid-1950s. CRCP has been constructed on nearly all urban freeways in the Chicago area and has shown excellent performance under severe weather and heavy traffic conditions. The effect of key design and construction parameters on long-term CRCP performance is investigated using a database that was compiled based on field surveys conducted from 1977 to 1994 by the Illinois Department of Transportation (IDOT). Analysis of the data shows the following variables have significant effects on performance: longitudinal reinforcement content (greatest effect of all variables), slab thickness (also very significant), traffic load applications, depth of reinforcement, base type, and D-cracking of concrete. CRCP built with tubes or chairs exhibited overall about the same performance. Experimental field studies in Illinois showed that depth of reinforcement has a large effect on crack width and, eventually, on punchouts. Specifically, the investigation indicated that CRCP sections with a slab 178 mm (7 inches) thick and steel content less than 0.6 percent developed the most structural failures. CRCP sections with a slab 254 mm (10 inches) thick and steel content from 0.7 to 0.8 percent developed the fewest failures. However, all the CRCP sections in this study, regardless of thickness designs and steel content, have typically carried more traffic than they were designed for and have lasted longer than their design traffic life.
This report reviews the design and performance of CRCP in Illinois, which has built more than 4,267 two-lane km (2,650 miles) of CRCP on the Interstate system since the mid-1950s. CRCP has been constructed on nearly all urban freeways in the Chicago area and has shown excellent performance under severe weather and heavy traffic conditions. The effect of key design and construction parameters on long-term CRCP performance is investigated using a database that was compiled based on field surveys conducted from 1977 to 1994 by the Illinois Department of Transportation (IDOT). Analysis of the data shows the following variables have significant effects on performance: longitudinal reinforcement content (greatest effect of all variables), slab thickness (also very significant), traffic load applications, depth of reinforcement, base type, and D-cracking of concrete. CRCP built with tubes or chairs exhibited overall about the same performance. Experimental field studies in Illinois showed that depth of reinforcement has a large effect on crack width and, eventually, on punchouts.
The design of rigid pavements according to AUSTROADS is a lengthy method. The designer assumes a pavement structure then uses a number of tables and figures to calculate the two governing design criteria, the flexural fatigue of the concrete base and the erosion of the subgrade/subbase. Each of these two criteria needs to be less than 100 percent. Ideally, they need to be at their maximum possible value that is less than 100 percent. Designers would repeat the design if either of the criteria is more than 100 percent, in other words, an unsafe design. However if the criteria are much less than 100 percent, i.e., over-design, most designers would stop after one or two iterations due to the lengthy process involved in calculating the criteria, and due to time limitations. This leads to designs that are safe, but not necessarily economical. This paper presents a formulation for the problem of optimum design of rigid road pavements by defining the objective function, which is the total cost of pavement materials, and all the constraints that influence the design. All these are given in terms of design variables and design parameters. The formulation, including the optimizer, was implemented in a spreadsheet. The optimization problem is used in a parametric study where 1,680 pavement structures are optimally designed.
The results of research conducted to improve guidelines for k-value selection for concrete pavement design are summarized. The research included a review of the evolution of the k-value concepts and methods, a review of k-value results from several field studies, an examination of the AASHTO Guide's k-value methods, and proposed new guidelines for selection of design k values by a variety of methods. The k-value was originally considered a useful and simple parameter for characterizing slab support provided by natural soils of fairly low shear strength. Recognizing that real soils are not true dense liquids, early researchers developed standardized test methods, which provided k values in good agreement with full-size slab deflections. Later, substantially higher k values were attributed to granular and stabilized base layers, based on plate tests on top of bases, although slab tests had shown that such bases did not increase k values. Based on the historical review, review of results from several field studies, and a thorough examination of the k-value methods introduced in the 1986 AASHTO guide, it is recommended that k values be selected for natural soil materials, and that base layers be considered in concrete pavement design in terms of their effect on slab response, rather than their supposed effect on k value. Improved guidelines were developed for determining k value from a variety of methods, including correlations with soil type, soil properties, and other tests; backcalculation methods; and plate-bearing methods. Guidelines also were developed for seasonal adjustment to k and adjustments for embankments and shallow rigid layers.
This study was conducted to characterize and compare currently available rigid pavement analysis models and design methods and to develop new rigid pavement designs to be evaluated in full-scale experimental projects. Analysis models investigated included ILLI-SLAB, JSLAB, WESLIQID, WESLAYER, JCS-1, H51, CRCP-2, and RISC. Design methods evaluated included AASHTO, Zero-Maintenance, JCP-1, California DOT, PCA, RPS-3 (Texas DOT), ARBP-CRSI, and Illinois DOT. Based upon the evaluation results, several models and methods are recommended for use in the development of new rigid pavement designs. A set of rigid pavement designs, featuring trapezoidal cross sections, widened PCC slabs, permeable drainage layers, longitudinal edge drains, shorter joint spacing, and tied PCC shoulders, was developed. Guidelines were also developed for joint load transfer design and joint spacing.
This textbook presents the theory of pavement design, describing pavement behavior and responses under various loading conditions, and including software available for the computation of stresses, strains, and deflections in both flexible and rigid pavement structures. Basic design elements (traffic loading, material characterization, drainage, and reliability) are presented, followed by a review of current highway pavement design procedures for both flexible and rigid pavements. Pavement overlay design procedures also are described in detail.
Three new design procedures have been developed for use on local agency projects. The design procedures are based on University of Illinois research documents and prepared under the guidance of a project advisory committee consisting of Federal, State, and local representatives. Information on the use of rigid pavements and on structural thickness determination, load transfer requirements, and reinforcement requirements are provided. A condensation of the IDOT subgrade stability manual is also included to provide guidance on subgrade stability requirements.
An in-depth. systematic examination is presented of the effect of temperature gradients on slab-on-grade pavements, whose main objective has been the development of practical design tools for use in a typical engineering office. This has been achieved by a critical reconsideration of the literature, a synthesis of currently available analytical resources, and the implementation of recent technological achievements promulgated in related areas of engineering. Prominent among these are the application of the principles of dimensional analysis, the finite element method, advanced statistical regression analysis, and artificial neural networks (ANN). A number of ANNs have been trained for the curling problem, and in several instances they are found to be more efficient predictive tools than corresponding statistical regression equations. It is found that the most important shortcomings of the Westergaard curling solution are his assumption of continuous contact between slab and subgrade (infinite slab self-weight), and his explicit treatment only of daytime conditions. Although Westergaard's curling-only predictions are significantly inferior to those from ANN and statistics, his load-plus-curling predictions exhibit approximately the same scatter as those from these two more modern and nominally more sophisticated tools. The case of Westergaard's curling solution can serve as an example pointing to the usefulness and desirability of theoretical solutions, even when these are only achievable on the basis of considerable abstraction and simplification.
Recently, a number of roads have begun to exhibit the onset of deterioration at relatively early ages. Since this deterioration appears to be the result of materials issues, data concerning raw materials, design, and paving conditions have been collected and analyzed for correlation between independent variables and deterioration. This analysis shows that there is a positive and statistically significant correlation between deterioration and the following variables: alkali and sulfate content of the cementitious materials, impermeable base course, paving temperature, and the presence of fly ash. This study also finds a significant need for improvement in data collection and maintenance by many organizations responsible for the production of concrete.
Current PCC pavement design practices and the key concrete pavement design features used by State highway agencies in the United States are summarized. This information was obtained from a comprehensive survey conducted in 1994 and 1995 under an NCHRP research project. Pavement types, design methodologies, and reliability levels are included, along with many design inputs. Parameters that the States use to characterize pavement site conditions, including climate, subgrade, and traffic, are given. The designed concrete slab thicknesses for different site condition combinations are compared. An analysis of variance compared the mean slab thicknesses designed in different climatic regions. This examination and summary of the details of current pavement design practices and design features for concrete pavements in the United States will be of interest to both pavement researchers and practitioners.
Over the years, pavement engineers have attempted to develop rational mechanistic-empirical (M-E) methods for predicting pavement performance. In fact, the next version of AASHTO's guide for pavement design will be mechanistically based. Many M-E procedures have been developed on the basis of a combination of laboratory test data, theory, and limited field verification. Therefore, it is important to validate and calibrate these procedures using additional data from in-service pavements. The LTPP program data provide the means to evaluate and improve these models. A study was conducted to assess the performance of some of the existing concrete pavement M-E-based distress-prediction procedures when used in conjunction with the data being collected as part of the LTPP program. Fatigue cracking damage was estimated using the NCHRP 1-26 approach and compared with observed fatigue damage at 52 GPS-3 test sections. Use of LTPP data was shown to successfully develop better insight into pavement behavior and improve pavement performance.
This study aimed to assess how well some of the existing concrete pavement M-E based distress-prediction procedures performed when used in conjunction with data being collected as part of the national LTPP program. As part of the study, appropriate data were obtained from the National Information Management System for the GPS-3 and GPS-4 experiments. Structural analysis was performed for up to 140 axle-load configurations for the selected test sections. Then, the ILLI-CONC software (developed under NCHRP 1-26) and PCA's procedures were used to predict fatigue cracking and joint faulting damage, respectively. The computed results were compared with observed values. This study showed that, even given the many current limitations in the LTPP database, LTPP data can be used successfully to develop better insight into pavement behavior and to improve pavement performance.
In 1982, four experimental sections of rigid pavement were constructed on Highway 3 southeast of Windsor to assess the comparative performance and overall serviceability of various pavement, drainage, and shoulder designs plus two types of surface textures. Recent innovative developments in concrete pavement design methodology, material specification, construction techniques, and pavement drainage systems prompted Ontario's Ministry of Transportation to construct these test pavements. Summaries of the design and construction details, plus the results of an on-going performance-monitoring program, are documented in this paper. The performance of the pavement section is described in terms of load transfer and pavement edge deflections based on FWD testing, pavement condition ratings, roughness, skid resistance, joint movement, and a crack survey. Observations of noise levels, traffic volumes, and surface textures are discussed. Conclusions based on 6 years of performance indicate the superior performance of the free-draining base materials. In addition, some anomalous behavior based on pavement cracking and roughness suggests additional areas of process control are warranted. (Note: An update on the performance of these experimental sections is presented by Kazmierowski and Bradbury, "Ten Years Experience with Experimental Concrete Pavement Sections in Ontario," Fifth International Conference on Concrete Pavement Design and Rehabilitation, Purdue University, West Lafayette, IN, 1993.)
This report documents the analysis and findings of a study to identify the site conditions and design/construction features of concrete pavements (JPCP, JRCP, CRCP) that lead to good performance and those that lead to poor performance. Data from the LTPP test sections were used along with findings from previous and ongoing analyses of LTPP data. As there were no known criteria for identifying performance expectations over time as good, normal, or poor, a group of experts was convened to establish criteria. Separate criteria were developed for performance in roughness, joint faulting, transverse cracking, and localized failures (CRCP).
Many significant site conditions and design/construction features were identified that lead to good and poor performance. The site conditions (traffic, climate, and subgrade) cannot be controlled by the designer, but steps can be taken to mitigate their effects. Several design and construction features can be controlled or specified by the highway agency; these should be given careful consideration. Knowledge of the design features identified as being critical to concrete pavement performance will contribute to improved guidelines for the design and construction of long-lasting PCC pavements.
Continuously reinforced concrete pavement (CRCP) performance depends on, among other factors, the characteristics of early developing cracks caused by environmental loads. The primary objective is to evaluate effects of design, materials, and construction variables on the characteristics of cracks in CRCP when subjected to environmental loads. A mechanistic model is developed using finite element formulations. Concrete and longitudinal steel are discretized using the plane strain and the frame elements, respectively. Various bond stress and slip models between concrete and longitudinal steel and between concrete and the underlying layers are developed using the spring elements. The creep effect is also included using the effective modulus method. CRCP responses from the model vary depending on the concrete and steel bond-slip models. An accurate bond-slip model needs to be investigated further by experiments to increase the accuracy of the mechanistic model. Concrete creep has beneficial effects on CRCP responses. The thermal coefficient of concrete has significant effects on CRCP responses. Using concrete with a low thermal coefficient will improve CRCP performance. Longitudinal steel variables-the amount of steel, bar diameter, and steel location-are important design variables that influence CRCP behavior. For given environmental conditions, an optimum steel design can be developed using the model developed.
Data on factors causing faulting in undoweled plain concrete pavements were collected. A large number of concrete pavement test sections located in southern Wyoming were included in the experiment. Extensive field data were collected on all test sections. These data included faulting over a 4-year period, traffic applications, construction information, annual precipitation, and drainage conditions. A statistical model was developed to predict joint faulting. The most important factors contributing to joint faulting were identified as traffic loadings, slab thickness, and edge drains.
This report describes an improved set of design and construction procedures for jointed reinforced concrete pavements. A systems approach was used to develop, analyze, evaluate, and implement recommended procedures for designing concrete pavement reinforcement and for determining sawing time and depth. An evaluation of the subgrade drag theory for reinforcement design indicated that it incorrectly predicts the required amount of reinforcement. Revised reinforcement equations are developed; these are believed to be more representative of actual conditions. Monte Carlo simulation was conducted to determine required sawing depths and times for a selected probability level.
A study of the performance of CRCP constructed on the Illinois interstate system has been conducted. Approximately 1,980 km (1,230 mi) of interstate pavement were surveyed, consisting of 175- to 250-mm (7- to 10-inch) slabs over granular and stabilized subbases. CRCP slab thickness, foundation support, and the presence of susceptible D-cracking aggregate were found to have a substantial effect on the performance of the pavements. Recommendations on the design and construction practices are made.
Currently, the United States has more than 30,000 lane miles of continuously reinforced concrete (CRC) pavements. Many are more than 20 years old and have provided excellent performance over the years. Much of the CRC pavement technology has developed through experience. This fact and the recent use of new design features (such as tied concrete shoulder, permeable cement-treated base, and epoxy-coated steel) pointed to a need to evaluate performance of existing CRC pavement sections. This paper summarizes the findings of a national pooled fund study (administered by FHWA) aimed at updating the state-of-the-art of the design, construction, maintenance, and rehabilitation of CRC pavements. As part of the study, a comprehensive field investigation of 23 in-service CRC pavements was conducted to study the effects of various design and construction features on performance of CRC pavements. The investigation included crack mapping/distress survey, profile/roughness measurement, FWD testing, and materials sampling and testing. In addition, the data collected to date from the 85 CRC pavement sections in the LTPP GPS-5 experiment were also analyzed. Key findings of the field investigation program as they relate to CRC pavement design and construction are presented.
This report describes the findings and recommendations of the follow-up U. S. Tour of European Concrete Highways, conducted October 10 to 22, 1992. The goal was to obtain sufficient information to construct experimental highway sections in Michigan and other States using the German design and to review an active construction project in Austria to obtain information on the exposed aggregate surface treatment technique to reduce tire/pavement noise. A major feature of the German cross section is the use of a 15 cm (6 cm) lean concrete or cement-bound pre-notched base, to which the concrete slab is bonded. Other major features are the provision of a thick granular blanket layer under the stabilized base and the provision of longitudinal edge drains, usually outletted to the storm drain system. Plate bearing quality assurance tests are run on the subgrade and the granular blanket surfaces to assure strong support for the stabilized pavement structure.
This study focused on the development of an alternative stress-estimation procedure to instantly calculate the critical stresses in jointed concrete pavements. The primary components of stress analysis, including gear configurations, total wheel load, tire pressure, a widened outer lane, a tied concrete shoulder, and thermal curling due to a linear temperature differential, need to be considered. The ILLI-SLAB finite element program was used for this analysis. In validation of the program, very favorable results were obtained in comparison with data from Taiwan's second northern highway, the AASHO road test, and the Arlington road test. Dimensional analysis and experimental design were employed to plan a factorial of finite element runs over wide ranges of pavement design parameters. Prediction equations for stress adjustments were then developed using a modern regression technique (projection pursuit regression). Subsequently, a simplified stress analysis procedure was implemented in a user-friendly computer program (TKUPAV) to facilitate instant stress estimation. Together with PCA's cumulative fatigue damage equation, a modified PCA stress analysis and thickness design procedure was also incorporated in the TKUPAV program. This program may be used not only for stress calculation but also structural analysis and design of jointed concrete pavement.
Determining the edge loading tensile bending stress in a concrete slab due to individual and combination effects of wheel loading and thermal curling is important to a mechanistic-based design procedure. The paper describes the identification of two additional dimensionless mechanistic variables, such that the problems encountered in previous investigations that have used dimensional analysis for thermal-related curling problems are resolved. A new regression technique (projection pursuit regression) together with traditional linear and nonlinear regressions is used to develop prediction models, which provide an accurate representation of the finite element model. They are simple, easy to comprehend, dimensionally correct, may be extrapolated to wider ranges of other input parameters, and are ready for implementation in a spreadsheet or computer program. Examples of practical applications using the new models are also provided.
A new predictive modeling approach is presented and the approach for localized failures in Illinois CRCP is demonstrated. Some data retrieval guidelines from the Illinois Pavement Feedback System database are first presented. A preliminary data analysis was conducted to assist in data cleaning and assessing the variability of the data before the analysis was performed. Several modern regression techniques ("robust" and "nonparametric" regressions) were introduced in a new predictive modeling approach. The proposed modeling approach was used to develop an improved model for localized failures in CRCP. The resulting model includes several variables such as cumulative ESALs, slab thickness, steel reinforcing content, steel reinforcing placement method, and base type for the prediction of CRCP failures. A sensitivity analysis was also performed to illustrate the effect of these variables on failures. Slab thickness and steel content are by far the most significant variables affecting performance. Crack spacing was found to have no effect.
The characteristics of cracks of CRCP are generally evaluated by analyzing the distribution of transverse crack spacing in the pavement. Statistical analysis of data produces the mean and the standard deviation of crack spacing. However, these parameters are not always sufficient for characterizing the crack spacing of CRCP. Therefore, this paper proposes an alternate method for analyzing the transverse crack spacing data. This method, maximum entropy spectral analysis (MESA), analyzes the data in this frequency domain rather than in the space domain. By using MESA, the uniformity and variability of crack spacing can be observed in the frequency domain. The results of analysis using MESA indicate that this method can intuitively distinguish the characteristics of transverse crack spacing distribution in CRCP containing different types of coarse aggregates.
This document presents design information for CRCP in highway applications. The focus of the document is on steel reinforcement design, with references to other procedures for structural thickness design. Key steel reinforcement factors included in the design procedure are PCC material properties (tensile strength, shrinkage, thermal coefficient of expansion, and modulus of elasticity), steel reinforcement properties (yield strength, bar size, thermal coefficient of expansion, and modulus of elasticity), base, subbase, and subgrade properties (elastic modulus values, layer thicknesses), wheel loading, climatic data (daily temperature differential and annual temperature difference), and pavement structure geometry (slab width, paving width, and distance to longitudinal construction joint). These factors, in conjunction with user-selected design limits on minimum crack spacing, maximum crack spacing, maximum crack width, and allowable steel stress, are used in a series of design equations to determine the required steel content. An accompanying computer program, CRC-HIGHWAY PAVE, is available to expedite the calculations.
This paper presents findings drawn from 12 years of monitoring and analyzing thermal cracking in experimental CRCP placed in and around Houston, TX. The purpose of the study was to evaluate new design elements and construction considerations intended to control early-age thermal cracking and cracking-related distress caused by coarse aggregate with a high thermal coefficient of expansion. Experimental factors considered include coarse aggregate type, percentage of steel reinforcement, bar size, double or single mat steel, paving time, and paving season. Findings from the study show significant differences in performance between low and high thermal coefficient aggregates, effective methods to minimize them, as well as some attempts that were not as successful. Aggregate type and placement season were found to be the most significant factors affecting PCC performance, whereas day or night placement, steel percentage, bar size, and skewed placement proved less significant.
The primary design variables and distress mechanisms that can cause varying degrees of transverse cracking in jointed concrete pavements are discussed. Included in the discussion is the Strategic Highway Research Program's LTPP program, which has collected a significant amount of condition survey data on more than 110 jointed plain concrete pavements and 65 jointed reinforced concrete pavements throughout North America over the past 7 years. A complete analysis of the transverse cracking that has occurred in the LTPP test sections, along with their respective relationships with the primary prediction variables found in the primary distress mechanisms, is provided.
A major national field and analytical study has been conducted into the effect of various design features on the performance of jointed concrete pavements. Extensive design, construction, traffic, and performance data were obtained from numerous experimental and other concrete pavement sections throughout the country. This volume provides a general evaluation of several concrete pavement design and analysis models. This includes RISC, ILLI-SLAB, JSLAB, H51, WESLIQID, WESLAYER, JSC-1, JCP-1, AASHTO, RPS-3, PCA, PMARP, PEARDARP, PREDICT, BERM, CMS, Liu-Lytton, JRCP-4, and California DOT procedures. Sensitivity analyses are included for each pavement sections. Also included in this volume is supporting documentation for the analyses presented in volume II.
This paper describes the performance of the Superstition Freeway (State Route 360) located near Phoenix, AZ. The construction of this freeway marked a new era in the concrete pavement design philosophies of the Arizona DOT. It was the start of what became a 16-km (10-mi) corridor of experimental test sections. The experimental sections consist of full-depth JPCP, JPCP over cement-treated base, JPCP over lean concrete base, and prestressed concrete pavement over lean concrete base. Performance evaluations based primarily on roughness and skid characteristics are presented, along with faulting, deflection, and maintenance data. A statistical analysis of Arizona DOT's pavement management inventory data was performed to develop linear models for both roughness and skid properties. The roughness models represent the expected roughness over the 20-year design life. The models representing skid properties could only be developed for the years in which the field data were collected.
This report covers the performance of experimental design and construction features implemented at four study sites. The first study site consisted of an experimental CRCP compared with JPCP with different design features. The second site includes a field trial of four different types of joint sealant materials. The third site included an evaluation of PCC pavements with experimental shoulder treatments, including PCC shoulders. The fourth site included an evaluation of other experimental bridge approach slabs and permeable asphalt-treated and cement-treated bases. Results from these studies are being reviewed and further experimentation, and in some cases implementation, of the design features is being conducted.
The purpose of this manual is to provide information on the background, rationale, and detailed behind the NYSDOT policy for thickness design of new and reconstructed pavements. It has been determined by the NYSDOT pavement design task force that positive pavement drainage and increased pavement life are important aspects in designing quality pavements. This manual is based on the 1986 AASHTO design guide for determining pavement thickness, as well as using a treated open-graded permeable base layer with continuous edge drains in the pavement structure for positive drainage. Rigid pavements will be potentially thicker slabs (up to 325-mm (13-inch) thick) and designed with full-depth tied concrete shoulders with widened PCC slabs to reduce critical edge and corner stresses. Dowel bars are recommended for all Interstate pavements, and additional select granular subbase may be required for certain conditions.
In 1975, the PCA conducted a survey of concrete pavement design and construction practices in the United States. This paper summarizes the design and construction practices by concrete pavement type, as well as typical construction costs. A field survey of 85 concrete pavement projects in 7 States also was conducted. Major problem areas noted in the survey for each pavement design type are summarized and recommended design and construction modifications are presented.
This study was conducted to evaluate and analyze PCC pavements to develop recommendations for the design and construction of long-lasting concrete pavements. It involved a detailed evaluation and analysis of the PCC pavement data in the LTPP database to determine the beneficial effects of specific design features and construction practices on long-term performance. This volume provides a concise summary of the results obtained from the study. It includes an overview of the engineering and statistical analyses that were conducted, and presents results that can be used by SHAs to obtain high-performance PCC pavements. The focus of the design and construction recommendations is on the prevention of key PCC pavement distresses.
The increasing use of CRCP around the world has led PIARC to prepare this synthesis on the state of the art of CRCP. The engineering and economic advantages offered by CRCP are described, followed by detailed discussions on the design (including steel design and terminal end movements), construction, performance, and maintenance and repair of CRCP. New developments in CRCP technology are also presented, along with main recommendations regarding its design and use.
A comprehensive evaluation of the various concrete pavement designs in the Phoenix, AZ urban corridor was conducted. This volume provides supporting project documentation to the main report. The appendices of this volume summarize the performance data for the sections; provide strip maps taken from the distress surveys; describe the creation and use of the project database; summarize the results from the weigh-in-motion studies; furnish rehabilitation selection guidelines; and provide an overview of recommended rehabilitation methods.
This bulletin provides methods for determining slab thicknesses adequate to carry traffic loads on concrete streets, roads, and highways. The thickness design procedure is based on mechanistic concepts calibrated to documented concrete pavement performance. Both a fatigue analysis (for the evaluation of the suitability of the slab thickness to withstand fatigue cracking from the projected traffic) and an erosion analysis (for the evaluation of loss of support at slab corners due to pumping under the projected traffic) are conducted. A simplified design procedure is also presented for use when detailed axle-load data are not available. The thickness design criteria are based on general pavement performance experience, and can be modified as particular climate, soil, or drainage conditions dictate.
The effect of rainfall on the performance of CRCP in Texas was studied by analyzing the condition survey data on CRC pavements throughout the State. Rigid pavement condition survey data were collected for 10 years, beginning in 1974. For the purpose of this study, the data were grouped into districts, and the average performance of pavements in each district was estimated. The average performance of CRC pavements was determined by adding the number of patches and punchouts in the pavement and estimating the number of failures per mile. The results of the study indicate that the average annual rainfall on the performance of CRC is significant. Although the initial performance of the pavements located in different rainfall areas is practically the same, when the pavement starts developing failures, the rate of failure development is affected by the average rainfall in the area. Pavements located in 250-mm (10-inch) rainfall areas generally showed an almost zero rate of failure development, whereas pavements located in 1,300-mm (52-inch) rainfall areas developed failures at a rate of about 0.6 failures per km (one failure per mi) per year.
This report describes the performance of the I-75 European concrete pavement reconstruction project approximately one year after construction. The experimental features of the pavement design were assimilated from designs used in Germany and Austria. The objective is to determine whether innovative features of typical rigid pavement designs used in European countries can be applied cost effectively to conventional design and construction methods used for rigid pavements in the United States. The European pavement is part of a major Michigan project to reconstruct 3.7 km (2.3 miles) of the I-75 (Chrysler) freeway in downtown Detroit. I-75 is 6 to 8 lanes wide and carries about 111,000 vehicles a day (11 percent are trucks). The approximately 1.6-km (1-mile) long European pavement is located on northbound I-75 just north of I-94. It will be monitored for 5 years. The experimental pavement appears to be performing as expected, except for the disappointing results pertaining to the exposed aggregate surface as a means to reduce traffic noise levels. Specific points of interest are as follows: No surface distress features, except for minor popouts, have developed on the European pavement, in contrast to the Michigan pavement, where 50 percent of the pavement panels have one or two transverse cracks; the ethylene propylene diene terpolymer joint seals are performing satisfactorily; the exposed aggregate surface appears to have lost macrotexture in the two inner lanes of northbound I-75, where traffic was during most of 1994 while southbound I-75 was being reconstructed; surface friction increased as expected; and the exposed aggregate surface provides only a slight reduction (0.4 dBA) in exterior and interior car noise levels, as compared to a reported 4 to 5 and 3.5 to 4.5 dBA, respectively, in Europe.
This technical digest has been prepared to concisely present current recommendations and guidelines on design and construction details for concrete pavements. Emphasis is given to JPCP, although a separate chapter on special design considerations for JRCP and CRCP is provided. This document is intended for use by design and construction engineers to assist in the development and construction of concrete pavements that perform better and last longer. Key topics covered include: concrete pavement type selection; subgrade preparation and characterization; drainage design; base and subbase considerations; thickness design; joint design; shoulder considerations; construction considerations; and special design considerations for reinforced concrete pavements. The recommendations and guidelines presented herein are based on recent research reports and concrete pavement performance studies. A detailed annotated bibliography of applicable documents from the past 10 years is included as an appendix.
A major national field and analytical study was conducted into the effect of various design features on the performance of jointed concrete pavements. Extensive design, construction, traffic, and performance data were obtained from numerous experimental and other concrete pavement sections throughout the country. This volume investigates the accuracy of several pavement performance models and illustrates the usefulness of several concrete design and analysis procedures. Performance models evaluated include AASHTO, PREDICT, PEARDARP, and PFAULT; design and analysis models evaluated include PMARP, JSLAB, ILLI-SLAB, CMS, Liu-Lytton, JCP, JCS, and BERM. Based upon the data collected from this and other studies, new prediction models were developed for selected performance indicators.
A major national field and analytical study was conducted into the effect of various design features on the performance of jointed concrete pavements. Extensive design, construction, traffic, and performance data were obtained from numerous experimental and other concrete pavement sections throughout the United States. This volume gives a broad overview of the work performed in this study. Summaries of the effect of various design features on concrete pavement performance are reviewed and performance trends identified. The accuracy of various prediction models and analysis methods are examined using the field performance data. From that evaluation, new prediction models were developed and a cost-effectiveness evaluation was performed.
A major national field and analytical study examined the effect of various design features on the performance of jointed concrete pavements. Extensive design, construction, traffic, and performance data were obtained from numerous experimental and other concrete pavement sections throughout the country. This volume presents a brief introduction to the data collection activities and presents a description and performance evaluation of the pavement sections in the study. Documentation is presented on the effects of slab thickness, base type, joint spacing, reinforcement, joint orientation, load transfer, dowel bar coatings, longitudinal joint design, joint sealant, tied shoulders, and subdrainage on jointed concrete pavement performance.
A major national field and analytical study examined the effect of various design features on the performance of jointed concrete pavements. Extensive design, construction, traffic, and performance data were obtained from numerous experimental and other concrete pavement sections throughout the United States. This volume provides detailed summary reports documenting the design, construction, and performance of the 95 concrete pavement sections in the study. Comprehensive summary tables compile the design and performance data from each section into a convenient format.
A major national field and analytical study examined the effect of various design features on the performance of jointed concrete pavements. Extensive design, construction, traffic, and performance data were obtained from numerous experimental and other concrete pavement sections throughout the country. This volume provides documentation of the data collection and analysis procedures used. The field data collection activities, including deflection testing and coring/boring, are discussed, as are the weigh-in-motion data collection procedures. Traffic computations and backcalculation methodologies are presented, along with the basis for the assessment of drainage conditions.
A comprehensive evaluation of various concrete pavement designs in the Phoenix, AZ, urban corridor was conducted. This volume summarizes the performance of the designs. Performance data are then used to evaluate the suitability of available pavement design models to Arizona conditions. The performance data were also used in developing design recommendations and in determining suggested rehabilitation activities for each section.
With the goal of improving future concrete pavement design and construction practices, this project evaluated the performance of 303 inservice concrete pavement sections located throughout North America. An extensive field-testing program, consisting of pavement condition surveys, drainage surveys, FWD testing, coring/boring operations, and roughness testing, was conducted to collect the information needed for analysis. Because many of these pavement sections are part of State-level studies on concrete pavements, a range of design variables (e.g., load transfer, slab thickness, joint spacing, drainage) thought to affect concrete pavement performance are present. Over one-third of the sections was evaluated under a preceding FHWA study; 5-year performance trends thus are available for some sections. Additional pavement performance data are also available for 96 European concrete pavement sections and for 21 Chilean concrete pavement sections. The average age and average cumulative ESALs for the North American sections are 16 years and 7.1 million, respectively, compared to 21 years and 21.8 million for the European sections, and 9 years and 5.9 million for the Chilean sections. This volume describes the field data collection activities conducted under the study and also summarizes the individual performance of the 303 concrete pavement sections evaluated. Pertinent design and construction data are given for each project, and key performance data are presented. Where available, 5-year performance trends are also summarized.
With the goal of improving future concrete pavement design and construction practices, this project evaluated the performance of 303 inservice concrete pavement sections throughout North America. This volume examines the performance of the various concrete pavement sections in the study. This examination primarily consists of an evaluation of the effect of concrete pavement design features on concrete pavement performance. Design features investigated include slab thickness, joint spacing, joint orientation, load transfer, joint sealant, base type, drainage, shoulder type, reinforcement, and pavement type. The results of an examination of the backcalculation results are also presented, as are the significant findings of an evaluation conducted on the performance of European and Chilean concrete pavements.
This paper presents recommendations for various aspects of concrete pavement design, based on the results of an evaluation of the performance of more than 300 concrete pavement sections in North America. Recommendations are presented for subgrade preparation, drainage, base type selection, shoulder/edge support type selection, concrete strength requirements, concrete thickness design, and joint design and construction.
Design and construction techniques as developed overseas have been used in South Africa on PCC pavements with little variation based on local experience. This paper describes the methodology by which jointed unreinforced concrete pavements are being evaluated with the aim of improving local design and construction techniques. Indications are that failures found on the pavements can primarily be attributed to inadequate construction techniques and control. Although the pavements are performing very well (only 11 percent show cracking outside the joints), it is felt that an improvement in performance is possible if subgrades are compacted properly to reduce settlement, nonerodible subbases are constructed, load transfer at joints is enhanced by low-shrinkage concrete, joints are kept properly sealed, and concrete shoulders are used.
This manual provides pavement design engineers with background information and recommended guidelines and considerations for the design and construction of concrete pavements. Items discussed include subgrade, bases and subbases, concrete materials, drainage, temperature and moisture effects, thickness design, joint design, and critical construction features. The approach presented incorporates consideration of all critical features during the design process, in contrast to focusing on thickness design only. Successful local experience and good construction practices are emphasized.
As part of the study reported here, analysis of data from the LTPP GPS-5 test sections was conducted to identify factors that influence long-term crack spacing in CRC pavements and to determine the effect of crack spacing on pavement performance. Data from the 85 test sections from the GPS-5 experiment were analyzed. Due to limitations of the available data and the lack of certain key data, the study did not produce definitive findings on factors that affect long-term crack spacing and CRC pavement performance. Lack of early-age cracking due to ambient weather conditions at the time of construction will continue to limit the value of GPS-5 to produce meaningful data on factors affecting early-age cracking. Continued monitoring of GPS-5 sites and subsequent data analysis should yield information on how CRC pavement cracking and performance changes with time, loading, and other factors. It is expected that as additional data from the GPS-5 experiment become available, more in-depth analysis of the test data to derive definitive results will be possible. Results to date, as presented in this report, do indicate that CRC pavements have the potential to provide long-term, low-maintenance service life as evidenced by the many well-performing sections in the LTPP GPS-5 experiment.
This is one of a series of reports prepared as part of a recent study (sponsored by FHWA) to update the state-of-the-art of the design, construction, maintenance, and rehabilitation of CRC pavements. In this report, the details of a comprehensive field investigation of 23 inservice CRCP sections are presented. The investigation included crack mapping and distress survey, profile and roughness measurements, FWD testing, and materials sampling and testing for 305-m (332-yard) long in-service test sections. Detailed, site-by-site design, construction, and performance summaries are presented for each project.
This is one of a series of reports prepared as part of a recent study (sponsored by FHWA) to update the state-of-the-art of the design, construction, maintenance, and rehabilitation of CRC pavements. This volume presents a comprehensive bibliography on CRC pavements, along with a summary of the current practice. The summary of practice provides brief details on the extent and practice of CRC pavement use in the United States and other countries.
This is one of a series of reports prepared as part of a recent study (sponsored by FHWA) to update the state-of-the-art of the design, construction, maintenance, and rehabilitation of CRC pavements. In this report, the results of a comprehensive field investigation of 23 in-service CRCP sections are presented; they show that there is a strong interaction among the steel content, concrete strength, and crack spacing. Steel contents in the range of 0.6 to 0.7 percent appear to provide desirable long-term average crack spacing in the range of 0.9 to 1.5 m (3 to 5 ft). Tied concrete shoulders did not appear to contribute to CRCP mainline performance, and the effect of base type on CRCP performance was not pronounced. The use of epoxy-coated reinforcement resulted in no undesirable cracking patterns.
This is one of a series of reports prepared as part of a recent study (sponsored by FHWA) to update the state-of-the-art of the design, construction, maintenance, and rehabilitation of CRC pavements. In this report, the critical distress types associated with CRC pavements are reviewed, and then maintenance and repair techniques are presented that address those critical distresses. Preventive maintenance methods presented include joint and crack sealing, undersealing, cathodic protection, and edge drains; repair methods presented include conventional full-depth patching and alternative patch types.
This study was conducted to evaluate and analyze PCC pavements to develop recommendations for the design and construction of long-lived concrete pavements. It involved a detailed evaluation and analysis of the PCC pavement data in the LTPP database using a variety of methods to determine design features and practices that have beneficial effects on long-term performance. Emphasis was placed on identifying specific design features that can be included during design to improve the performance of PCC pavements under various combinations of environmental and traffic loading conditions, and for different subgrade support conditions. The study focused on the development of practical recommendations that can be implemented by highway agencies to increase pavement life. This volume describes and provides information on improved distress and roughness prediction models developed as part of the study. A key focus was to develop distress and roughness prediction models that incorporate mechanistic principles but are still practical for use by SHAs.
This study was conducted to evaluate and analyze PCC pavements to develop recommendations for the design and construction of long-lived concrete pavements. It involved a detailed evaluation and analysis of the PCC pavement data in the LTPP database using statistical techniques to determine design features and construction practices that have a beneficial effect on long-term performance.
CRC pavements have been used in Belgium since the 1950s. Over that time, the longitudinal reinforcement content has been reduced. Transverse reinforcement is placed obliquely to prevent ill-timed initial cracking above the transverse rods. A 6-cm sandwich layer of a bituminous mixture is placed between the concrete slab and the lean concrete base. The depth of the reinforcement in early projects was 6 cm; this was later increased to 9 cm. Overall, CRC pavements have performed very well, with no punchouts, minimal crack breakdown, and minimal reinforcement corrosion.
This report summarizes a 22-year study of concrete pavement design features that included constructing a test road with numerous design variables, two roads with several major design changes, and several roads among the first to incorporate a major change in load transfer devices across transverse joints. Performance of each item is discussed, along with a number of minor changes. Many findings have been implemented and have improved the performance and cost-effectiveness of rigid pavements in New York State.
This report documents the field performance of nine concrete pavement projects that incorporate recycled concrete aggregate (RCA) in the construction of the pavement. Multiple sections were evaluated on many of the nine projects due to perceived differences in performance levels or variations in pavement design (such as the use of virgin aggregate or the inclusion of dowel bars). All told, a total of 17 sections (of which 12 contain RCA) were subjected to an extensive field testing program consisting of pavement condition surveys, drainage surveys, FWD testing, coring, and serviceability assessments. Each section is described in detail. Performance observations and results from the FWD and laboratory testing are presented, with emphasis on evaluating the effect of RCA on pavement performance. An overall summary synthesizes the findings and conclusions of the field tests.
As part of the European Concrete Pavement Evaluation System (COPES) program, 77 concrete pavement sections from France, Italy, the United Kingdom, and Belgium were monitored and the data evaluated with the objective of providing continual improvements to the design, construction, and maintenance of concrete pavements. An overview of the data collected under the European COPES program is presented, along with a general look at overall performance trends. The European sections are all characteristic of the wet-freeze environmental region. Because of higher legal axle weights and longer design periods, European pavements are often exposed to many more ESAL applications than pavements in the United States. Of the sections evaluated, the most common pavement type is jointed plain concrete pavement. Extensive uses of stabilized bases, positive drainage features, and dowel bars are also evident. A qualitative analysis was conducted using present serviceability rating (PSR), age, and traffic as the principal parameters. The use of lean concrete bases and incorporation of a greater number of modern elements (e.g., dowel bars and positive drainage) improved the performance of the pavement sections. Models predicting the PSR of the pavement sections were also developed.
With the goal of improving future concrete pavement design and construction practices, this project evaluated the performance of 303 in-service concrete pavement sections throughout North America. This volume includes supporting documentation used in the research study. Summary tables containing design, construction, and performance data for the concrete pavement sections evaluated under this study are presented in appendix A. Appendix B presents a summary report prepared on the performance of 77 European concrete pavement sections. Appendix C presents a summary report prepared on the performance of 21 concrete pavement sections in Chile.
This comprehensive guide was prepared for WSDOT personnel in design, constructing, and maintaining highway pavement structures. A broad overview of pavement engineering is presented, followed by detailed chapters on key pavement areas: fundamental design parameters (including materials characterization, traffic loading, and climatic factors), pavement evaluation procedures (including condition surveys, roughness testing, structural evaluation, and skid resistance), pavement response determination, AASHTO new and overlay design procedures, pavement rehabilitation methodologies, life-cycle cost analysis procedures, subsurface pavement drainage considerations, and specific pavement construction considerations.
This report summarizes the efforts to date within Caltrans to improve JPCP performance. It recommends changes to transverse joint spacing, load transfer design, joint sealing, longitudinal joint design, and base type and selection. One important finding is the effect of climate on JPCP faulting and cracking performance. Recommendations to reduce climatic effects on JPCP performance are given.
This report provides background on previous research efforts by Caltrans and others in the area of PCCP design and performance that can be used to improve current rigid pavement performance. Much work has been done in this area, and a review of these findings is useful in updating current rigid pavement design standards. Based on the review here, it is recommended that skewed joints spaced at 3.7, 4.6, 4.0, 4.3 m (12, 15, 13, and 14 ft) intervals be maintained; that 760-mm (30-inch), No. 5 tiebars be installed along all longitudinal joints at 760-mm (30-inch) centers; that all transverse joints be sealed with silicone sealant material; that treated permeable bases be used when feasible (pending the results of further studies); and that tied PCC shoulders be employed on all new designs.
The Texas DOT is a decentralized organization consisting of 24 geographical districts. Each district makes its own decision on what pavement type will be designed and constructed. However, the Department's use of concrete pavements in highway projects has increased significantly over the past decade, especially in urban areas and in high-truck-traffic corridors. A paper presented at the Fourth Purdue conference in 1989 described and analyzed the use of the 1986 AASHTO Design Guide in designing concrete pavements in Texas. This paper discusses other aspects of Texas DOT concrete pavement design and construction practices, as well as research underway to improve design and construction methods.
The primary factors to be considered in the design of CRCP are the structural responses: crack spacing, crack width, and steel stress. These responses are the outcome of the interactions among materials characteristics, environmental conditions, and traffic loading. Since at least three-quarters of the concrete volume is occupied by aggregate, critical concrete properties (such as thermal coefficient, tensile strength, modulus of elasticity, and drying shrinkage) are different for concrete made with different types of coarse aggregate. In this study, proposed CRCP design standards were evaluated for concretes made with various coarse aggregate types, namely siliceous river gravel (SRG) and limestone (LS). Generally, the standard provided a good design, although it was determined that two-layer reinforcement is desirable for SRG concrete at slab thicknesses greater than 325 mm (13 inches), and for LS concrete at slab thicknesses greater than 225 mm (11 inches). An analysis of the CRCP deformed wire standard indicated that wire spacings of 450 mm (18 inches) or greater are required.
This widely used textbook presents the basic principles of pavement design for both flexible and rigid pavement structures. It includes a discussion of theories of stress distribution for both pavement types, and presents a summary of key design factors and considerations: subgrade, drainage, paving materials, traffic, and climate. Design methodologies for both pavement types are also presented; and pavement distress types and rehabilitation strategies are discussed.
This paper describes the current state of the art of concrete pavement construction in the United States, along with changes made to accommodate the increases in traffic volumes and loadings. Typical concrete pavement designs used for primary highway paving, airfield paving, and parking lots and truck terminals are presented. Developments in paving equipment over the past 30 years are described. Design changes that improve the performance of PCC pavements are reviewed, along with examples of innovative technology.
With the goal of improving future concrete pavement design and construction practices, this project evaluated the performance of 303 inservice concrete pavement sections throughout North America. This volume presents pavement performance prediction models that were developed from the data collected under this study. Prediction models are presented for transverse joint faulting (doweled and nondoweled), transverse cracking (JPCP and JRCP), transverse joint spalling (JPCP and JRCP), pavement serviceability (JPCP and JRCP), and pavement roughness (JPCP only). Based on the results of the models and on the results of the field evaluation findings, guidelines are presented for the improved design of concrete pavements.
The structural response of jointed plain concrete pavement slabs was evaluated using data obtained from instrumented slabs that were a part of newly constructed JPCP on I-70 in Colorado. The instrumentation consisted of dial gauges for measuring curling deflections at the slab corner and longitudinal edge and surface-mounted strain gauges for measuring load strains at the longitudinal midslab edge. The through-thickness temperature profiles in the pavement slabs were also measured at 30-minute intervals during the field test. Analysis of the field data showed that the instrumented slabs had a considerable built-in upward curling and that concrete slabs on a stiff base can act completely independent of the base or monolithically with the base, depending on the loading condition. The built-in upward curling of the slabs has the same effect as negative temperature gradients. These findings suggest that the effects of temperature gradients on the critical edge stresses may not be as great as previously thought and that the corner loading, in some cases, may produce more critical conditions for slab cracking. Another important finding of the study is that a physical bond between pavement layers is not required to obtain a bonded response from concrete pavements.
This paper discussed current CRC design concepts as well as proposed modifications and improvements to the current design procedure. Current CRC design methodology consists of the prediction of crack spacing by contraction restraints, the selection of limiting criteria to avoid punchout failures, and the estimation of the required pavement thickness based on these limits. This approach, however, does not take into account shear and load transfer across the transverse cracks. Therefore, this procedure alone is insufficient for characterization of failure modes including punchouts.
The load transfer efficiency is an important parameter in selecting a pavement thickness. This efficiency depends on loading conditions, as well as required performance conditions. Crack spacing, crack width variability, and the load transfer efficiency all must be included to sufficiently describe the failure mode of the slab. Each of these topics, as well as their usage in the modified CRC design, is discussed.
Causes for distress in CRCPs are presented. Primary types of distress leading to a reduction in service life are punchouts and crack spalling. Causes for both the punchout and spalling distresses were determined to be loss of load transfer across transverse cracks. Loss of load transfer over time was correlated with the crack opening and the loss of support due to erosion and pumping of the subbase. Crack opening was correlated with crack spacing. A design procedure is proposed based on the capability of the system to transfer load across the cracks, which in turn is dependent upon crack spacing. Consequently, it is necessary to be able to predict crack spacing before the design procedure can be applied. While crack spacing can be controlled to some extent by the amount of reinforcing steel used and steel placement, the dominant factor in crack spacing appears to be climatic conditions at the time of construction.
This report is one of a series of reports prepared as part of a recent study sponsored by FHWA aimed at updating the state-of-the-art of the design, construction, maintenance, and rehabilitation of CRCP. The scope of work of the FHWA study included: (1) conduct a literature review and prepare an annotated bibliography on CRCP and CRCP overlays; (2) conduct a field investigation and laboratory testing related to 23 existing in-service pavement sections to evaluate the effect of various design features on CRCP performance, to identify any design- or construction-related problems, and to recommend procedures to improve CRCP technology; (3) evaluate the effectiveness of various maintenance and rehabilitation strategies for CRCP; and (4) prepare a summary report on the current state-of-the-practice for CRCP. Each of the above four items is addressed in a separate report. This report, Volume VI in the series, addresses several factors associated with CRCP performance, as well as several recently suggested improvements to the design, construction, and evaluation of CRCP.
This report is one of a series of reports prepared as part of a recent study sponsored by FHWA aimed at updating the state-of-the-art of the design, construction, maintenance, and rehabilitation of CRCP. The scope of work of the FHWA study included the following: (1) conduct of a literature review and preparation of an annotated bibliography on CRCP and CRCP overlays; (2) conduct of a field investigation and laboratory testing related to 23 existing in-service pavement sections to evaluate the effect of various design features on CRCP performance, to identify any design or construction related problems, and to recommend procedures to improve CRCP technology; (3) evaluate the effectiveness of various maintenance and rehabilitation strategies for CRCP; and (4) prepare a summary report on the current state-of-the-practice for CRCP. Each of the above four items is addressed in a separate report. This report, Volume VII in the series, serves as a synthesis of CRCP performance, design, construction, and rehabilitation.
The primary objective of this project was to identify improved methods for draining rainwater from the surface of multi-lane pavements. Improved methods for draining water from the surface of multi-lane pavements are needed because of the important role that drainage plays in the mitigation of hydroplaning and tire splash and spray. Because the tendency for hydroplaning and tire splash and spray depend on the thickness of the film of water on the pavement, an interactive computer program (PAVDRN) was developed for predicting the flow and flow path length of rainwater flowing across the pavement surface. Based on the computer program, surface drainage recommendations were developed (see PTI 1998 reference, number 12, in this section).
This paper presents an overview of drainable pavement systems for use on PCC pavements. Critical elements of the drainable pavement system include the permeable base (drainage layer), the separator layer, and the edgedrain system. The permeable base must provide adequate permeability to allow the flow of water through the material, sufficient stability to support paving operations, and adequate strength to contribute to the structural design of the pavement. The separator layer is placed between the permeable base and the subbase/subgrade to prevent subgrade soil particles from contaminating the base. The edgedrain system is designed to remove the water from the permeable base and outlet it to the ditches.
This report presents results of interviews with State highway department personnel, field reconnaissance of pavements in nine States, and nine case studies of selected pavements. Problems with existing drainage design concepts and construction methods are noted, showing why many pavements remain saturated for extended periods of time. This saturation contributes to considerable shortening of pavement life. A new method of design is presented to take care of the infiltration of surface water. Inflow-outflow analyses and highway geometrics are included in a procedure using a two-layer graded filter to rapidly remove water entering the structural layers.
This synthesis reviews the current practices in pavement subsurface drainage and presents critical design factors and appropriate design methods for pavement subsurface drainage. It focuses on the development of consistent practices in the drainage components of pavement design and discusses the effects of good and poor subsurface drainage. Also reviewed is the impact of decisions in planning, budgeting, procurement, construction, and maintenance on drainage performance. Results of a survey of state transportation agencies on current pavement drainage strategies are interjected throughout the discussion to emphasize the important issues that influence design decisions. Critical subdrainage design details, proper construction techniques, and planned subdrainage maintenance activities are also described to ensure the functionality of the subdrainage system.
This report documents the results of 287 video inspections of highway edgedrain systems in 29 States. Findings indicated not only that the equipment was quite effective in identifying edgedrain performance concerns, but also the widespread nature of concerns about edgedrain performance. Almost one-third of the systems inspected had nonfunctional outlets, and another one-third either had nonfunctional mainlines or the mainlines could not be inspected due to physical obstructions. Only one-third of the systems inspected were found to be performing as intended. Based on the results of the study, recommendations are provided for edgedrain design improvements to facilitate performance of the systems and their inspections and also to improve quality control during construction. A draft guide specification for video edgedrain inspection is provided in an appendix.
This paper addresses key installation issues affecting the performance of geocomposite pavement edgedrain systems. This includes maintaining the verticality of the drain panel in the trench; proper positioning of the drain panel within the trench; backfilling with open-graded coarse aggregate; timely installation of outlet fittings and pipe; and the use of outlet pipes with adequate pipe stiffness. Three highway rehabilitation projects involving the installation of approximately 120 km (400,000 linear feet) of geocomposite edgedrains in Virginia and Ohio are investigated, and lessons learned documented in this paper. Actual cost savings, up to 50 percent, were realized from the use of geocomposite edgedrain compared to conventional edgedrains. Conclusions and recommendations are presented in support of successful installations.
This course notebook presents state-of-the-art guidelines and recommendations on the selection, design, construction, and maintenance of drainable pavement systems. With the focus on rigid pavements, it presents background information on the detrimental effects of moisture on pavement performance and describes a methodology for computing effective drainage times of a pavement structure. Guidelines on the design and construction of both treated and nontreated permeable bases are provided, along with detailed information on separator layer requirements and on longitudinal edge drain design. Recommended drainage maintenance practices are also described.
This manual is an updated version of the Geotextile Design and Construction Guidelines manual used in the FHWA/NHI training course Geosynthetics Engineering Workshop. The update was performed to reflect current practices and codes for geotextile design, and has been expanded to address geogrid and geomembrane materials. The manual was prepared to enable the highway engineer to correctly identify and evaluate potential applications of geosynthetics as an alternative to other construction methods and as a means to solve construction problems. With the aid of the text, the highway engineer should be able to properly design, select, test, specify, and construct with geotextiles, composite drains, geogrids, and related materials in drainage, sediment control, erosion control, roadway, and embankment on-soft-soil applications. Steepened slope and retaining wall applications also are addressed. Applications of geomembranes and other barrier materials to highway works are also summarized.
This report contains the results of a thorough study of geosynthetics in highway drainage applications. Ninety-one geosynthetics drainage systems in 17 States were exhumed and inspected, with the results incorporated into a database. The performance of the applications was compared against design predictions and construction techniques. These evaluations showed that the existing design methodology is acceptable for granular soils but that the criteria for fine-grained soils may need to be evaluated on a site-specific basis. Also, specific recommendations have been made in regard to the construction practices associated with prefabricated, geocomposite edge drains.
In northern climates, subsurface road drainage involves the presence of materials with large pores within the frost-penetrated zone. One road design uses horizontal open-graded drainage layers (OGDL) directly under the pavement and connected to edge drains. In some instances, thin geotextiles with pores smaller than those of OGDL have been used as drainage layers. These drains are subject to extreme weather conditions: the proper evacuation of water from pavement cracks, joints or unpaved shoulders can be hindered if it freezes inside and blocks the system. This paper presents the results of a testing program designed to simulate these conditions using a needle-punched geocomposite. The premise is that the input of heat from the water flowing through the fibers is sufficient to compensate the influx of cold from the confining medium. A polypropylene geocomposite, consisting of coarse filaments sandwiched between two filter layers, was tested. The samples were confined by materials of different thermal conductivities: concrete slab or sand layer with degrees of saturation of 0, 70 and 100 percent. Water was circulated vertically and horizontally through the sample for 30 days inside a freezing cabinet. The applied flow rates of 100 and 600 ml/min per linear meter corresponded to the minimum (winter) and maximum (thaw) observed in a field-test section. Intermittent flows were also applied to simulate alternating daily freeze-thaw conditions. The tests showed that total blockage by ice is unlikely inside vertical edge drain but possible in horizontal blanket layers.
This report, in five chapters, provides detailed guidelines on the design of subsurface drainage systems. Chapter I is devoted to a general discussion of the adverse effects of subsurface moisture, the sources of subsurface moisture, and the types of subsurface drainage installations to control this moisture. Chapter II lists the data requirements for analysis and design and presents recommended procedures for assembling these data. Chapter III presents methods and recommended criteria for the control of groundwater and infiltration in pavement structural sections. Chapter IV deals with the more general control of groundwater away from the pavement. Chapter V discusses the construction and maintenance aspects of subdrainage systems.
This document provides guidance on how to modify highway pavement designs to minimize the potential for hydroplaning. Recommendations are provided in each of four principal design areas: environmental conditions, surface geometry, pavement properties, and appurtenances. The recommendations must first be field tested and eventually may be considered for inclusion as AASHTO design standards.
This paper summarizes the recommendations on drainage and erodibility of concrete pavement foundations presented in the 1987 PIARC publication "Combatting Concrete Pavement Slab Pumping - State of the Art." Classifications were established for criteria that have a major impact on the long-term behavior of concrete pavements, namely: (1) drainage of infiltration water at slab-subbase-shoulder interface, (2) use of low-erodibility materials at interfaces, and (3) optimization of interface drainage and waterproofing of pavements. The gains in service life achieved with improved drainage and low-erodibility materials can be objectively assessed.
This user's manual provides instructions on the operation of the new Microsoft® Windows®-based microcomputer program entitled DRIP (Drainage Requirements in Pavements). It provides detailed instructions on the operation, use, and application of the software, and also contains general information on drainage design methodology. Example problems are provided to fully illustrate and demonstrate the capabilities of the program; these include performing drainage designs for flexible and rigid pavements, calculating time-to-drain and depth of flow in the drainage layer, performing separator layer and geotextile designs, and performing edgedrain and geocomposite fin drain design.
The highest level of stress and deflection in PCC pavement is found at the joints. In highway pavements, the stress is highest along the longitudinal joints, and deflection is highest at the corners. In airport pavements, the highest stresses may occur at either the transverse or longitudinal joints, depending on the aircraft wheel configuration and the pass-to-coverage ratios. Because the joints experience the highest amount of stress or deflection, cracking, pumping, and faulting usually start at the joints. Several methods have been developed to enhance performance at transverse and longitudinal joints. Some of the more common methods are increasing slab and base course thickness to improve aggregate interlock, protecting the base and subgrade against water intrusion, installing permeable bases, reducing joint spacing, and installing load-transfer devices. Industry practice and research have determined that smooth, round, corrosion-resistant dowel bars are typically most effective in maintaining load transfer throughout the life of a pavement. This guide provides a summary of the benefits and design procedures applicable when dowel bars are used as a load-transfer device.
This publication addresses the design and construction of joint systems for concrete highway pavements (which typically range in thickness from 200 to 350 mm (8 to 14 inch)). The need for joints in concrete pavements is first discussed, including a description of the mechanisms of natural crack development due to thermal and shrinkage stresses. The various types of joints are described, and special emphasis is placed on the design of transverse joints, including recommendations for spacing, skewing, load transfer, and construction (dowel placement, sawing, sealing). The design and construction of other joint types (construction joints, expansion joints, longitudinal joints) are also described.
The objective of this study was to compare the performance of a nonreinforced concrete pavement with randomly spaced, skewed contraction joints using dowel bars versus one without dowel bars. A control section and a test section, each 1.6 km (1 mi) in length, were incorporated into a highway improvement project located just west of Menomonie, WI, in Dunn County. Construction took place in 1984. The doweled test section has performed well, while the nondoweled control section has experienced progressive deterioration, primarily in the form of faulting. Due to the poor performance, in 1994, after 10 years of service, the entire project length of nondoweled pavement, including the control section, was diamond ground. A recent field survey showed the 12-year-old doweled pavement to be in good condition, while the ground nondoweled pavement is beginning to show signs of reoccurring faulting. It has been estimated that the nondoweled pavement will require grinding twice to attain a service life equivalent to that of the doweled pavement. The conclusions from this project are as follows: (1) the doweled pavement continues to perform better than the nondoweled pavement; (2) the life of the doweled pavement is estimated to be approximately 2.5 times longer than the nondoweled pavement prior to any maintenance or rehabilitation; (3) the epoxy-coated dowel bars in the test section remained intact (i.e., no corrosion); (4) the use of dowel bars increases initial concrete pavement cost by approximately 7.8 percent; (5) over a 25-year service life, a nondoweled pavement would cost approximately 13.1 percent more than a doweled pavement; (6) the use of dowel bars in concrete pavements currently saves WisDOT approximately $6,000,000 per year; and (7) the employment of dowel bars is a cost effective method of extending the service lives of concrete pavements while enhancing the pavement performance and reducing user inconvenience.
This paper presents the results of several field investigations to evaluate the effectiveness of automatic dowel bar inserter equipment to properly place dowel bars in rigid pavements. A commercially available radar system capable of locating steel embedded in concrete was used in the evaluation of dowel bar alignment on projects using the dowel bar inserter. Overall, the inserter performed well compared to the basket assembly construction, with dowel depth, misalignment (vertical and horizontal), and longitudinal displacement being comparable between the two methods.
Joints are constructed in concrete pavement to control stresses and cracking and thus to prevent pavement damage and loss of riding quality. Unfortunately, much of the maintenance required for jointed pavements is necessitated by the joint itself. Common joint-related distresses include pumping, spalling, blowups, and faulting, although joint designs or construction practices often may lead to other pavement distresses (e.g., late sawing can lead to slab cracking). This synthesis presents background information on the causes of these common joint-related distress types, and describes recommended design and construction practices to prevent their occurrence. Detailed rehabilitation methods for addressing joint-related distresses are also described, ranging from temporary maintenance measures intended to maintain pavement serviceability to permanent rehabilitation techniques in which the joint is restored to a condition where it can perform its intended function for the remaining life of the pavement.
Current pavement design in Iowa calls for the inclusion of load-transfer dowels in transverse joints in both State and local pavements. The dowels have been included to protect the pavement against faulting of the joints and other forms of distress resulting from erosion of the soils from beneath the joints. Faulting has been found to be present mostly at the outer edges of the driving lane. Iowa Highway Research Board Project TR-420 is directed at the evaluation of placing alternative numbers of dowels in the transverse joints of the pavement. One rural and one urban pavement were selected for the test sites on county highways near Creston, IA. The sites include subsections containing zero dowels in the transfer joint, three or four dowels in the outer wheel path only, and a full basket of dowels across the joint. This paper discusses the results of deflection testing in both wheel paths in both pavement directions on the rural and urban sections. Fault measurements, joint opening widths, and visual distress surveys have been conducted twice per year on each of the projects. The construction projects are now 12 months old, and the response to load in each case can now be evaluated.
A procedure to design transverse joints to control faulting has been developed. The procedure is based on two design models (one for doweled and one for nondoweled pavements) incorporating mechanistic concepts and calibrated with field performance data. The models consider many important design factors known to influence joint faulting, including traffic loading, dowel diameter and spacing, joint spacing, temperature factors, subdrainage, base type, subgrade soil, shoulder type, and the concrete thermal coefficient of expansion.
In 1991 and 1992, test sites were constructed to evaluate the performance of joint seal materials and installation methods in new and old concrete. Five joint resealing sites were installed under the Strategic Highway Research Program (SHRP) project H-106 using 12 materials and 4 installation methods. Additionally, 6 new joint sealing sites were installed under the SHRP SPS-4 supplemental testing program using 20 materials and 5 installation methods. Yearly rigorous evaluation of the effectiveness of these seals has been conducted, providing 7 years of performance data regarding adhesion and cohesion failure, spall distress, and compression seal failures.
This paper summarizes the final analysis results from these studies, providing material effectiveness rankings, life-cycle cost evaluations, installation method rankings, and other performance results.
This advisory provides guidance and recommendations relating to the design and construction of joints in conventional PCC pavements. The various joint types found in PCC pavement are defined; guidelines and recommendations on their use, design, and construction are then presented. Information on transverse contraction joints (spacing, load transfer, joint reservoir design), construction joints (transverse and longitudinal), longitudinal contraction joints, and expansion joints is provided.
This document summarizes a roundtable discussion of the effects of joint sealing on pavement performance. Various highway agencies and representatives from the FHWA, academia, industry, and the consulting field discussed the relative benefits of joint sealing and exchanged viewpoints. Many questions were brought to the table, and it was suggested that a synthesis-type document be prepared to fully summarize the issues surrounding joint sealing and its cost-effectiveness.
The Pennsylvania Department of Transportation (PennDOT) decided to change its practice of using skewed joints after reviewing the results of a LTPP program analysis project. The project analyzed LTPP pavement performance data to identify what worked and what didn't work to control the development of joint faulting. As of calendar year 1999, Pennsylvania policy specified perpendicular joints for any limited-access, four-lane concrete pavement highway projects. By changing its pavement joint design standard, PennDOT can reduce the occurrence of joint faulting and realize the following benefits: a smoother ride for motorists; reduced construction problems and related costs; reduced maintenance requirements; and fewer maintenance-related disruptions to traffic.
This paper describes an experiment, conducted by the PIARC Technical Committee on Concrete Roads, on the Namur Test Road in Belgium, to observe the behavior of six different types of contraction joints: sealed and unsealed joints with evenly spaced dowels; sealed and unsealed joints with variably spaced dowels; and sealed and unsealed undoweled joints. These joints were in a concrete pavement constructed on top of an existing asphalt pavement. On average for all joint types, only about one-third of the joints were found to be active, which discounts the validity of predictions of joint widths for individual joints. Nonetheless, the average joint opening over lengths of 20 slabs was consistent with values predicted as a function of thermal expansion and shrinkage. No influence of sealing on joint behavior was observed.
This project continued investigative efforts of the earlier project 1371. The project completed laboratory tests including relaxation tests, bond-strength tests, and fatigue tests for various sealant materials, and also established a field test site of a variety of joint sealants to monitor performance. The researchers constructed a material behavior model based on finite-deformation viscoelasticity as a function of temperature, deformation, and age effects. They studied the correlation between natural and artificial weathering and proposed a sealant-performance model. Based on this model, this report provides a procedure for estimation of the service life of a sealant in concrete pavement joints. Material and pavement engineers can use this procedure for design and maintenance purposes. This report also proposes a specification and a test protocol for joint sealant materials, which incorporate performance-prediction procedures. The proposed guidelines can be verified and refined through continuous observation of the field test sections. Project researchers expect that application of the research products will lead to an improved sealant selection process and reduced maintenance cost for concrete pavements.
This paper provides a rational, mechanistic method for analysis, design, and evaluation of doweled joints in concrete pavements. The required inputs to the analytical model are the slab thickness, modulus of subgrade reaction, and the radius of the loaded area. All other model inputs can be set at default values or modified at the designer's discretion. Dowel bar diameters and spacings can then be interactively modified by the designer to yield a given level of load transfer capability at the joint. The same relationships can be used to evaluate the load transfer efficiency of in-service joints by entering FWD-measured joint deflections. The method can be used to backcalculate joint material and structural properties, as well as stress load transfer at the joint. The design and analysis procedures presented in this paper ignore the effects of curling and warping. Obviously, daily and seasonal temperature and moisture cycles have a significant influence on pavement response. Further investigation of the effects of environmentally induced responses is needed.
A finite-element investigation was made of the behavior of jointed or cracked pavement systems equipped with a pure-shear load transfer mechanism, such as aggregate interlock. Dimensional analysis was used in the interpretation of the data, leading to a general definition of the relative joint stiffness of the pavement system in terms of its structural characteristics. Results of this study were verified by comparisons with earlier published field, laboratory, and analytical information. The investigation demonstrated that deflection load transfer efficiency is related to stress-load transfer efficiency, and that this relationship is sensitive to the size of the applied load (or to the gear configuration). A simple backcalculation procedure is outlined to evaluate the in situ joint stiffness of such pavements. Pure-shear load transfer devices are shown to be particularly desirable under a combined externally applied and thermal loading condition because they offer no additional restraint to longitudinal curling.
This paper describes and evaluates the development of mechanistic-empirical algorithms for more realistic estimates of anticipated faulting in concrete pavements. Earlier theoretical investigations are considered, interpreted through more recent finite-element analysis results, and calibrated using an extensive database of field observations. A factor influencing faulting is the dowel-concrete bearing stress, for which an improved method of determination is presented. A procedure is outlined for assessing the need for dowels in both plain and jointed reinforced concrete pavements, and determining the bar diameter needed to prevent significant faulting. Application of the procedure is facilitated through use of the program PFAULT, which can be implemented on a personal computer.
This paper describes the development of faulting prediction models for doweled and undoweled joints, based on mechanistic concepts as well as analysis of field data. Site conditions (traffic, climate, and subgrade) and several design features (dowel diameter, subdrainage, joint spacing, base type, and slab widening) were found to enter significantly into the faulting prediction models.
This paper summarizes findings of past research and experience in the United States and foreign countries in the design of doweled JPCP. The need for dowels on medium and heavy truck traffic routes is emphasized. Recommendations are given on the design of doweled joints, dowel diameter, dowel length, dowel spacing, bondbreaking, corrosion protection, contraction joint spacing, dowel alignment tolerances, and dowel placement.
The objective of this paper is to analyze the feasibility of using corrosion-free fiberglass reinforced plastic (FRP) devices in lieu of steel tie bars in the longitudinal joints of highway concrete pavements. The FRP devices are designed to provide the same shear transfer capability as the currently used steel tie bars. FRP devices consisting of bars, channel, and I-beam shapes are considered. In terms of cross-sectional area, the amount required for FRP devices is greater than that for steel bars because the modulus of elasticity of the FRP is lower than that of steel. In terms of cost of materials, FRP devices are more expensive than steel tie bars. However, prevention of deterioration due to corrosion may extend the service life of the joints and therefore that of the pavement. More research is needed to accurately define the increase of service life when corrosion is prevented.
FHWA has been involved in a number of research activities to determine the need for dowel bars in jointed PCC pavements. Recent activities are summarized, and the most recent models developed to predict transverse joint faulting of doweled and nondoweled pavements are presented. The faulting models are recommended for use in checking the adequacy of proposed project designs. Future research activities pertaining to load transfer design are also discussed.
PCC pavements require joints to control the natural cracking associated with shrinkage caused by drying and with movements caused by changes in temperature and moisture conditions. This report records the state of the practice with respect to the design, construction, and maintenance of PCC pavement joints. An overview of concrete pavement jointing is presented, including a description of current practices used by highway agencies. This is followed by general joint design considerations, such as load transfer needs, joint spacing requirements, and joint reservoir and sealant design. A discussion on current joint construction practices and quality control considerations is also provided to illustrate critical construction requirements, and a summary of recommended joint repair and maintenance practices is presented.
This report discusses the evolutionary developments in mechanistic dowel behavior theory over the past 70 years. New findings relating to dowel bar behavior obtained from finite-element modeling are described. A sampling of pavement performance models that use empirical or mechanistic-empirical statistical regressions to estimate load transfer performance (expressed as joint faulting) is presented. The findings from a limited number of field performance and laboratory studies are summarized. Recommended construction procedures associated with transverse joint construction are also presented.
In the past few years, the subject of sealing joints in rigid pavements has become a rather controversial issue. Many highway agencies have made or are considering significant modifications to the rigid pavement joint sealing practices, namely leaving joints unsealed or sealing narrow joint sawcuts. This paper reviews the current rigid pavement joint sealing practices and summarizes the most recent information on the effectiveness of joint sealing. It is observed that, in terms of subgrade erosion, joint sealing may not be cost effective in pavement locations with free-draining, coarse-grained subgrade material, or in a location where pavement joints are thermally locked. However, neither of these cases adequately addresses the issue of reducing the infiltration of pavement compressibles and the resultant buildup in expansive pressures that can lead to joint spalling and blowups.
The subject of sealing concrete pavement joints has been studied for many years, and a wealth of technology exists for successfully installing pavement joint seals. However, in practice, a great deal of inadequate performance has been observed by highway agencies in the United States in recent years. One primary reason for the observed problems is inadequate control of construction processes. Another very significant factor affecting the performance of joint seals is climatic conditions. This paper examines the effects of climate on the movement of rigid pavement joints.
Joint and sealant studies of PCC pavements must address whether joint sealing enhances total pavement performance and is cost effective, and, if so, what sealant system should be used. WisDOT has been studying the effect of PCC joint/crack sealing on total pavement performance for 50 years. By 1967, there was substantial documentation that filling and refilling of contraction joints had no beneficial effect on pavement performance. By 1984, it was concluded that pavements with unsealed joints had better overall performance (distress, rid, materials integrity) than pavements with sealed joints. In 1990, WisDOT passed a policy eliminating all PCC joint sealing in new construction and maintenance. This "no seal" policy has saved the State $6,000,000 annually with no loss in pavement performance and with increased customer safety and convenience. The entire PCC sealing issue is beginning to be addressed at the national level, ensuring no false assumptions and with the customers' needs in view.
There is an ongoing drive toward improvements and achieving success in effective and long-term sealing of PCC pavement contraction joints. A variety of joint sealing products and procedures have been applied in Iowa in search of improvements in seal performance. Hot-poured rubberized asphalt products were mainly used for sealing all joints in earlier years for highways. In the 1980s, silicone sealant products were becoming popular, especially for major highways. As a high level of sealant performance was not achieved from silicones in Iowa conditions, other sealing products were tried. Preformed neoprene compression seals are being tried as a substitution for silicone sealants. Due to high costs of materials and installation with neoprene seals, the search for improvements through other joint sealing products and procedures continued. An agreement was made to provide and install preformed ethylene propylene diene monomer compression joint seals. The research site was a 183 m (600 ft) test section of northbound I-29 in Pottawattamie County, IA. Seal installation was done on August 20, 1992. Seal performance has been good over the past 7 years and the seals still show no significant signs of decreasing performance.
This report presents results of an investigation conducted to develop placement tolerances for dowels in concrete joints. A theoretical analysis of dowel misalignment was attempted, but because of the complexity of incorporating the three-dimensional nature of dowel misalignment, the theoretical analysis was not completed. The effect of dowel misalignment was then investigated in the laboratory by conducting pull-out tests on sections of concrete slabs incorporating dowels with different levels of misalignment. Results of this laboratory testing showed that pullout loads are relatively low for dowel misalignment levels of less than 25 mm per 450-mm (1 in per 18-inch) length of dowel bar.
This report contains the results of a study conducted to improve rigid pavement joint systems. The study included a literature review, development of a finite-element analysis computer program, laboratory testing, and evaluation of various methods to improve rigid pavement joints. The conclusion: solid steel dowel bars are the most cost effective load-transfer device, and nonuniformly spaced dowel bars are recommended to be used on a trial basis. The use of tied PCC shoulders and widened PCC slabs is also recommended to improve joint performance.
In 1984, the Portland Cement Association revised its concrete pavement thickness design procedure for highways and streets to incorporate consideration of erosion as well as fatigue. The erosion criteria were added because heavy axle loads cause deflections at slab edges and corners and edges, which cause pumping, erosion, voids, and faulting. The erosion criteria correlated well to all of the in-service performance data available at that time, including data from the AASHO road test and several States. These criteria were viewed as first-generation general guidelines that could be refined as field performance data became available on specific climatic and drainage conditions. The objective of this study described in this paper was to collect performance data that have become available since 1984 and refine the existing erosion criteria to represent different climatic areas and drainage conditions.
This report discusses the use of joint sealants and provides background information for considering joint sealing in concrete pavements. It contains the current practices of each State and some new performance information on hot-pour, silicone, and preformed compression seals. The report also defines the primary considerations that would accompany elimination of joint sealing. Further investigation and deliberation beyond this report are necessary to reach a final conclusion.
Joint sealant is a material that minimizes both infiltration of surface water and incompressible material into the joint system. Sealants also reduce the potential for dowel bar corrosion by reducing the entrance of de-icing chemicals. The other function of joint sealants is to prevent incompressible material from entering the joint reservoir. Many advances have been made in joint sealant materials; the current research determined whether they improve pavement performance. Common joint sealants in pavement applications include hot-pour liquid sealants, silicone sealants, and compression seals.
This report contains a summary of the current practice for considering maintenance concerns in the highway design process, including those involved in pavement design. Strengths and weaknesses of the various methods are described and areas needing particular improvement are identified. A process designed to explicitly recognize the maintenance implications of designs and design elements is presented, along with the demonstration results gained from the trial implementation of the process in an SHA. Finally, common highway design details that create significant maintenance problems are listed with recommended solutions to accommodate maintenance concerns.
This synthesis describes the state of the practice with respect to setting a coherent strategy of cost-effective preventive maintenance for extending pavement life. It discusses the practices of State, local, and Provincial transportation agencies that are attempting to minimize life-cycle costs of pavements and are identifying, during the design of pavement rehabilitation, reconstruction, or construction projects, the future preventive maintenance treatments and the timing and funding for those treatments. It includes a review of domestic literature and a survey of current practices in North America. The appendices include a primer on pavement design and construction, the benefits of preventive maintenance of pavements, a summary of the questionnaire data collected, a simulation of pavement management strategies, and an example process to demonstrate the cost-effectiveness of preventive maintenance.
This report describes the preventive maintenance practices of several highway agencies, along with the rationale for these practices. It covers the history of preventive maintenance and describes critical issues such as funding considerations, strategy development, and cost analysis. Recommendations regarding current practices and future funding schemes are also included.
Well-designed and well-constructed concrete roads generally require little maintenance, which is one of their main assets. However, maintenance is still required for the road's design life to be fully realized. Furthermore, inadequate designs or poor construction practices can hamper the performance capabilities of the concrete pavement, thereby further necessitating the need for timely and effective concrete pavement maintenance. Because it has been proven that the durability of concrete structures depends on the quality of the maintenance, it is now advisable to locate as early as possible those areas exhibiting evidence of wear and fatigue. Procedures to assist in this identification process are included in this document. In addition, a range of diagnostic and rehabilitation equipment is now available for concrete pavements, and can be used to assess and predict the performance of a network or a part of a network. Various solutions are available to improve or repair deteriorated concrete pavements and are presented in this document.
This document serves as the participant's reference manual for a FHWA/NHI training course on pavement preventive maintenance. Preventive maintenance, often summed up as "applying the right treatment to the right pavement at the right time," is becoming increasingly popular in highway agencies interested in overall pavement preservation. The objectives of this manual and course are to introduce the components of a pavement preventive maintenance program, to define potential treatment techniques and materials, to describe the relationship between pavement management and pavement preventive maintenance, and to explain cost/benefit concepts of preventive maintenance to decision makers.
The material is organized into seven modules that are intended to meet the above-stated objectives. The first module is an overview of pavement preventive maintenance. This is followed by background information on the current status of preventive maintenance, appropriate definitions, objectives of preventive maintenance programs, and barriers to success. The next module introduces the most commonly used maintenance treatments for both asphalt concrete surfaced and PCC pavements. Because economic analyses are so important to evaluating the cost-effectiveness of treatments, a module on cost analyses is included.
This expert report provides a comprehensive survey of hot-dip galvanizing and epoxy-or-PVC-coating protection systems for steel reinforcement. It examines influences on materials and application in manufacturing, performance in concrete environments, and practical experience. It also offers guidance on the choice of protection systems.
This report documents the performance of experimental concrete pavements in Japan. A conventionally designed jointed reinforced pavement has been constructed that contains a deformed bar running longitudinally near the outside edge of the slab. These pavements have shown very good performance, with the additional bar controlling crack widths and crack deterioration.
A modification of the reinforcement formula that considers the realistic frictional characteristics of subbase types is presented. The objective of this study is not to abandon the current formula but to arrive at a better formula, one that considers the field observations. Rational reinforcement design is important because the amount of reinforcement affects the restraint on the movement of a pavement section, or slab, and the long-term performance. The reinforcement formula was modified in accordance with the experimental results obtained concerning subbase frictional resistance. The new formula represents the actual components of frictional resistance at the interface: adhesion, bearing, and shear. The formula calculates the steel requirement for the middle of the slab; in other words, the calculated value is the maximum requirement, and the locations between the free end and the middle of the slab will require less reinforcement. Further experimental study is necessary to calibrate the new formula.
In this paper, a CRCP design procedure is presented along with the necessary limiting criteria. This procedure is derived from theoretical and empirical models developed in connection with numerous field and laboratory studies. The first basic concept is to provide adequate longitudinal steel considering the specific conditions of a project to achieve a desirable crack width, crack spacing, and steel stress. These limiting criteria are shown in this paper. A check is also made to limit spalling and other distress manifestations from occurring. The AASHO Guide for Design of Pavement Structures is recommended for pavement thickness design.
This paper describes a study that was conducted to investigate the effect of coarse aggregate types on the performance of CRCP built in Texas. Long-term performance studies of CRCP in Texas show that performance is a function of coarse aggregate type. A laboratory-testing program was conducted to determine the effects of coarse aggregate type on concrete properties. Hypothetical pavement sections varying in thickness and steel contents were then analyzed with a mechanistic model to obtain estimates of performance. From the laboratory and performance analyses, reinforcing steel design charts were developed for pavements built with either limestone or siliceous river gravel aggregates.
This report reviews the performance of concrete pavements constructed in Japan and also reports on available structural design methods. The performance of reinforced and nonreinforced pavements is evaluated and the suitability of current structural design methods to the design conditions in Japan is explored.
Results are presented of a laboratory investigation to determine the properties of fiber-reinforced concretes (FRCs) with steel (hooked-end), polypropylene (monofilament and fibrillated), and the recently introduced polyolefin fibers (monofilament) for application in pavements and bridge deck overlays. Concrete properties in the unhardened and hardened states were evaluated and compared. Although the ultimate splitting tensile strength, compressive strength, and first-crack strength were higher in most of the FRCs, when strength values were adjusted for changes in air content, only a few batches had higher strengths. The addition of fibers resulted in great improvements in flexural toughness and impact resistance. Three FRC pavement overlays were applied in Virginia in 1995. The FRCs used in the projects were similar to those used in the laboratory investigation, with similar fiber volumes, types, and sizes. To implement the findings of the study successfully, the performance of the FRC pavement overlays is being monitored.
JRCP develops transverse cracks as the drying and thermal shrinkage of the concrete is resisted by the friction with the supporting layers. These cracks deteriorate with time and traffic because of the loss of load transfer capacity. However, rapid deterioration of these cracks has been observed on some recently constructed projects. This rapid crack deterioration leads to accelerated maintenance requirements and shortened service lives. A synthesis of factors that may reduce aggregate interlock load transfer is presented and current research efforts aimed at evaluating the relative effects of these factors are described. Test variables selected for study include coarse aggregate type, coarse aggregate gradation, coarse aggregate treatment (virgin, recycled, blended), coarse aggregate source, foundation support, reinforcement content, and type and amount of slab tension.
Ramakrishnan, V. and N. S. Tolmare. 1998. Evaluation of Non-Metallic Fiber-Reinforced Concrete in New Full Depth PCC Pavements. Final Report. Report No. SD96-15-F. South Dakota Department of Transportation, Pierre, SD.
This final report presents the construction and performance evaluation of a new full-depth pavement, constructed with a new type nonmetallic fiber-reinforced concrete (NMFRC). The mixture proportions used, the quality control tests conducted for the evaluation of the fresh and hardened concrete properties, and the procedure used for mixing, transporting, placing, consolidating, finishing, tining, and curing of the concrete are described. Periodic inspection of the full-depth pavement was done and this report includes the results of these inspections. The feasibility of using this NMFRC in the construction of highway structures has been discussed. The new NMFRC with enhanced fatigue, impact resistance, modulus of rupture, ductility and toughness properties is suitable for the construction of full-depth pavements. However, a life-cycle cost analysis shows that NMFRC is not a favorable choice because of its high initial cost.
Research was conducted to evaluate the relative effects of several factors on the deterioration of transverse cracks in jointed reinforced concrete pavement. Thirty-five large-scale pavement sections were cracked at an early age and subjected to repeated applications of simulated heavy vehicle loads. Test variables included coarse aggregate type, source, and grading (including use of recycled concrete, slag, and blends of manufactured and natural aggregates); slab tension (simulated varying panel lengths and foundation friction); reinforcing steel type (smooth and deformed wire mesh and deformed bars); reinforcement quantity; and foundation support. Deflection, load transfer, and crack width data were collected at predetermined test intervals. This paper discusses the research findings related to the effects of reinforcement design and foundation stiffness on transverse crack performance. Test results indicate that the deterioration of transverse cracks can be mitigated by providing strong foundation support, thereby reducing the magnitude of the relative vertical displacements of the two slab fragments at the crack. The use of slab reinforcing designs that hold the cracks more tightly closed also provided improved crack performance.
Suh, Y. C. and B. F. McCullough. 1994. "Factors Affecting Crack Width of Continuously Reinforced Concrete Pavement." Transportation Research Record 1449. Transportation Research Board, Washington, DC.
Crack width is an important factor affecting the behavior and performance of CRCP. Wide cracks can lead to various pavement distresses, including spalling, punchouts, and steel rupture. Various factors affecting CRCP crack width were evaluated on the basis of width measurements of 208 transverse cracks randomly selected from a series of experimental test sections constructed in Houston. The crack widths were measured at various times and slab temperatures by using a microscope with a graduated eyepiece. It was found from a statistical analysis of the collected data that the factors that significantly affect crack width are construction season, coarse aggregate type, amount of steel, and time of crack occurrence. Thus, hot weather placement produced much wider cracks than cool weather placement. The use of siliceous river gravel resulted in cracks wider than those associated with the use of limestone, and the difference was larger at lower temperatures. The greater the amount of longitudinal steel, the narrower the crack width. Cracks occurring during the first 3 days of construction were significantly wider than those that occurred later. Finally, the effect of crack spacing on crack width was found to be insignificant.
This study identified sources of stress in the longitudinal steel of JRCP, evaluated the effectiveness of current longitudinal design procedures, and included an analysis of the stress state of the longitudinal steel that can be used to check the adequacy of any reinforcing design. The analysis revealed that even pavements containing a sufficiently high amount of longitudinal reinforcing, such that all stresses are within their allowable limits, are failing prematurely. One reason for this may be because neither current design procedures nor the proposed mechanistic analysis considers fatigue of the steel. A mechanistic design procedure that accounts for fatigue can be developed after the effects of multi-axle loading and varying load magnitudes are determined.
Results of laboratory and field tests conducted to study the freeze-thaw durability of FRC are presented. Test data suggest that FRC is more resistant to freeze-thaw environment than plain concrete, irrespective of the number of cycles. The short metallic fibers apparently contribute to frost resistance of FRC due to their positive effect on the bond strength between fibers and matrix. A prototype FRC slab pavement constructed in the field exhibited good performance. Visual inspection of the prototype pavement indicated that FRC is sufficiently durable and resistant to spalling and scaling by frost action commonly observed in plain concrete pavement in cold regions of China.
Most maintenance activities on CRC pavements are related in one way or another to punchout distress. Over several years of observation of CRC pavement, several symptoms related to the structural aspects of punchout distress have been noted, including, but not limited to: close crack spacing, surface widening and spalling of transverse cracks, development of longitudinal cracking, loss of load transfer, and subbase and subgrade pumping. Literature reviews have elaborated on punchout-related factors with respect to pavement performance. However, the punchout mechanism relating the various factors is not completely defined. Some questions exist concerning the sequence of events leading to the loss of load transfer across transverse cracks as a prerequisite to the development of a punchout. This sequence of events relates to the role reinforcement plays in the punchout process and whether the loss of aggregate interlock requires rupturing of the steel. If rupturing of the steel occurs, the question is whether it occurs before or after the loss of aggregate interlock. Factors related to punchout distress (as noted by this investigation and others) are reviewed and a possible mechanism of punchout distress is addressed.
A study was undertaken at the University of Illinois to develop a mechanistic design approach for CRCP to account for punchout distress. A mechanism relating to the loss of load transfer and the progressive development of punchout-related distress is presented. Analysis procedures, demonstrated to implement the mechanism as a rationally based thickness design procedure for CRCP, suggest that the optimal crack interval is between 0.9 and 1.2 m (3 and 4 ft). Current CRCP design methodologies focus on limiting cracking intervals, crack width, and stress in the reinforcement. Load-transfer mechanisms have not been considered in the limiting design criteria and consequently are not included in these design procedures. These methods attempt to determine the design pavement thickness based on the combined effects of environmental and load-related stress on the final crack spacing, which must be limited to the design cracking criteria. However, past experience has indicated that a certain percentage of crack spacing usually falls below the specified minimum crack interval. These data suggest a greater tendency for punchouts to develop within this lower range of crack spacing. How pavement thickness, percent reinforcement, and crack spacing may be considered with respect to pavement spalling and loss of load transfer in the process of punchout development are outlined.
Two sections of interstate highway in central Oklahoma were recently reconstructed. On both projects, northbound lanes were reinforced with epoxy-coated steel and southbound lanes were reinforced with uncoated steel. Two crack surveys were conducted over the entire length of both sections of new pavement. The results of these surveys show that epoxy coating has no significant effect on crack spacing. Additional variables evaluated include concrete strength, air temperature, and air content. The data indicate that air temperature and air content have the greatest impact on crack spacing. A second phase of the study involved the construction of laboratory specimens with either uncoated or epoxy-coated reinforcement. Cracks were artificially induced in specimens by placing the specimens in tension. No significant differences were measured in either crack spacing or crack width.
The smoothness or riding comfort of PCC pavements is the highest indicator of quality from the user's perspective. Therefore, the smoothness of newly constructed PCC pavements is of high interest. Since its development in 1990, the Kansas PCC pavement smoothness specification has undergone several revisions. The 1996 revision changed the incentive/disincentive payment from a percent of bid unit cost for the PCC pavement paving basis to a dollar-based value. This revision of the PCC pavement smoothness specification is primarily an attempt to make this smoothness specification more compatible with the asphalt concrete smoothness specification, which has been based on dollar value. This paper primarily outlines the current PCC pavement smoothness specifications in use in Kansas and also updates this development.
Most pavement management activities include the use of devices that measure longitudinal profile for assessment of surface roughness. Although technology has been available for measuring longitudinal profile for decades, its still has not fully matured. In fact, a prevailing sense exists in the highway community that if each agency measured the same road with its device, there would be a variety of results. This project sought to improve the accuracy and consistency of roughness measurement through the development of guidelines for network-level and project-level measurement of longitudinal pavement profile. The resulting guidelines are based on the determination of factors that affect roughness measurements, the quantification of the effect of these factors on repeatability and accuracy, and the determination of how and when these factors can be controlled. The research also sought to explain the underlying causes of common profile measurement problems to assist agencies charged with measuring longitudinal profiles in maximizing the quality of their pavement management system's roughness estimates.
SHAs throughout the United States use smoothness specifications to ensure they are providing the public with quality roads. Some SHAs even provide monetary incentives to contractors for building smoother roads. The effectiveness of such incentive policies, though, has not been studied. This report describes a study to determine whether the initial roughness of a pavement section has any influence on its long-term performance. Statistical and graphical analyses were performed on asphalt and concrete test sections in Wyoming. The findings indicate that the initial roughness of concrete pavements based on the Profilograph Index do not correlate with the long-term performance of these pavements. However, initial roughness measurements based on the International Roughness Index do correlate with future roughness measurements.
This report describes the findings and results of research conducted to determine (1) the effect of initial pavement smoothness on the future smoothness and future life of various pavement types; (2) the effect of smoothness specifications on initial pavement smoothness; (3) the cost-effectiveness of smoothness specifications (including incentives/disincentives); and (4) the most suitable types of smoothness measuring equipment and smoothness reporting indices for use in future smoothness specifications. Detailed analyses of comprehensive time-series smoothness data showed that initial pavement smoothness has a significant effect on the future smoothness of the pavement in 80 percent of new construction (both AC and PCC pavements) and in 70 percent of AC overlay construction. Furthermore, using two different analysis techniques, it was illustrated that added pavement life can be obtained by achieving higher levels of initial smoothness. Combined results of both roughness model and pavement failure analyses indicated at least a 9 percent increase in life corresponding to a 25 percent increase in smoothness from target profile index (PI) values of 0.11 and 0.08 m/km (7 and 5 inches/mi) for concrete and asphalt pavements, respectively. Cost-effectiveness analyses conducted on several pavement families showed that the most cost effective smoothness levels are considerably higher than what is typically used as the current target (PIs between 0 and 0.08 m/km (0 and 5 inches/mile) versus PIs between 0.08 and 0.16 m/km (5 and 10 inches/mi)). Moreover, theoretical pay adjustment functions for the pavement families examined showed greater maximum incentive amounts and more punitive disincentive amounts than current pay adjustment functions. A detailed evaluation of smoothness-measuring equipment resulted in recommended requirements for measured profile wavelengths, sampling interval, distance accuracy, vertical elevation accuracy, and other considerations. Reviews of various smoothness indices, in terms of their ability to correlate with user response and other smoothness indices, resulted in the international roughness index (IRI) and the PI being ranked highest, followed closely by the Michigan DOT ride quality index, the Janoff ride number, and the Sayers ride number.
Pavement performance is commonly evaluated using the concept of pavement serviceability, in which pavement failure is defined by terminal serviceability instead of strict structural failure. The present serviceability index (PSI), the measure of pavement serviceability, is a function of pavement roughness, cracking, patching, and rutting. Pavement roughness is the major component of PSI and represents more than 95 percent of its value. Because roughness is such as important consideration, changes in roughness control pavement life cycles, and, therefore, construction quality, which influences roughness, performance, and life cycle, as well. A case study of a $120,000,000 project is presented. In this project, poor workmanship and lack of smoothness testing led to a notably high initial roughness. A study was conducted to quantify the long-term effects of the high initial roughness. Results indicate that the pavement service life of the project will be reduced significantly. In addition, a huge increase in the project life-cycle costs is expected. In another study, consideration was given to some of the available smoothness evaluation criteria in which roughness indices, such as the international roughness index and PSI, are used. Results of the study showed that most of these criteria are not capable of adequately addressing the high roughness associated with repeated transverse pumps. Recommendations for overcoming this inadequacy are presented.
This strategic safety plan for the Nation's highways is based on a coordinated effort between a host of public and private transportation agencies and other groups interested in highway safety. The objective of the plan is to outline strategies in 17 key emphasis areas that have the potential for saving lives in the magnitude of 5,000 to 7,000 each year, as well as substantially reducing health care costs. Key emphasis areas are young drivers, suspended/revoked drivers, older drivers, aggressive/speeding drivers, impaired drivers, keeping drivers alert, safety belts, pedestrians, bicyclists, vehicle train deaths, motorcyclists, heavy trucks, safety enhancements in vehicles, keeping vehicles on the roadway/minimizing the consequences of leaving the roadway, intersections, work zones, and survivability of severe crashes. One important strategy recommended to help keep drivers alert and to help keep vehicles on the roadway is the retrofitting of rumble strips on the shoulders of rural interstates and other facilities prone to cause driver fatigue.
A particularly troublesome part of the pavement-shoulder system is the joint at the interface of concrete mainline pavements and bituminous shoulders. This discontinuity has often permitted undesirable amounts of surface water to reach vulnerable bases, subbases, and foundation soils, causing them to soften, swell, or become adversely affected by freeze-thaw action. Subsequent deterioration of the shoulder surface at the joint, and often extending 0.6 m (2 ft) or more away from the joint, has been a particularly vexing problem.
A wide variety of pavement-shoulder joint systems were reviewed in 15 states and detailed longitudinal joint movements recorded at several sites. These field observations, coupled with the results of other field and laboratory studies, provided the bases for a number of recommendations for longitudinal joint and shoulder design and construction.
Past field studies of lateral distribution of trucks on highway pavements are limited in their relevance to current design practices and truck size limits. In particular, little information is available on the effect of widened concrete slabs on lateral distribution of trucks. The Illinois DOT has constructed test sections of "widened-lane" (or more properly called widened-slab) pavements with 46-cm (18-in and 51-cm (20-in extensions on I-57. Truck wheel placements on these test sections were compared with those observed on nearby conventional 3.65-m (12-ft) pavement slabs, in a study conducted at the University of Illinois. Continuous filming of truck wheel positions was performed with an 8-mm camera mounted on bridges over the highway. Wheel positions were determined to within approximately 12 mm (0.5 in precision by scaling distances measured on the films to known dimensions on the pavements. The mean placement of the wheels of over 900 trucks observed on the control sections was about 56 cm (22 inches) from the slab edge. About 2.5 percent of the wheels passed within 15 cm (6 inches) of the slab edge. On the widened-slab sections, the mean placement of truck wheels was about 5 cm (2 inches) closer to the lane edge (marked by the paint stripe) but still 96 to 102 cm (38 to 40 inches) away from the slab edge. No slab edge loadings were observed among more than 1,300 observations of truck wheel placements on the widened-slab pavement sections. The results suggest that slab widening is likely to be a cost-effective design improvement for concrete pavements that otherwise would be vulnerable to transverse fatigue cracking as a predominant mode of failure.
This advisory outlines recommended practices for the design and construction of paved shoulders. Guidance is provided on the selection of shoulder types with specific design recommendations presented for both asphalt and concrete shoulders.
Single vehicle run-off-the-road crashes result in approximately one-third of all highway fatalities and one-half million people injured annually, with a societal cost of $80 billion each year. Continuous shoulder rumble strips (CSRS) are one countermeasure used to address this significant safety problem. This study extracted data for two States (California and Illinois) from the Highway Safety Information System to estimate the safety effects of CSRS on freeways. Before-after evaluations of CSRS projects with the use of different comparison groups were conducted. The results from the evaluations estimate that CSRS reduce single-vehicle run-off-the-road crashes on average by 18.3 percent on all freeways (no regard to urban/rural classification) and 21.1 percent on rural freeways. Two potential adverse effects related to safety with CSRS were analyzed: (1) the crash risk that CSRS may present due to driver startle/panic response, and (2) the effect of CSRS on crash migration. Findings show that these potential adverse effects are insignificant.
Rumble strips provide motorists with an audible and tactile warning that their vehicle is approaching a decision point of critical importance to safety or that their vehicle has partially or completely left the road. Rumble strips can be installed either in the traveled way of a roadway or on the roadway shoulder. This synthesis describes the current state of the practice on the use and effectiveness of rumble strips in both applications. Recommended designs and guidelines on the uses of rumble strips are also provided.
This is the fourth and final report of a study to determine the effect of concrete shoulders, lane widening, and frozen subgrade on concrete pavement performance. In this portion of the study, nondestructive deflection testing was conducted over a 2-year period to determine seasonal effects on pavement deflections. Deflections taken during the frozen portion of the year are about one-tenth as great as those taken during the nonfrozen portion of the year. Tied concrete shoulders appeared to reduce edge deflections by about 15 percent. The use of widened PCC slabs reduced deflections at the pavement lane edge by 27 to 46 percent depending on the width of the widening.
This report describes the thickness design of roadway shoulders and is based on mechanistic principles of stress-strain analysis. Both flexible and rigid pavements can be designed with this method. The shoulders may be adjacent to either rigid or flexible pavements. All shoulder-pavement type combinations are possible, including the use of a widened rigid mainline lane with a flexible shoulder. The inner and outer edges of the shoulder are designed by computing stress-strain responses due to encroaching or parked vehicles and then applying fatigue distress functions to determine thickness requirements. Drainage design is also considered as part of the shoulder design process.
Continuous shoulder rumble strips create noise and vibration that alert wayward drivers that they have wandered from the main traffic lanes. Many highway agencies have adopted CSRS on many paving projects. This report examines the use of CSRS and evaluates their effectiveness.
This paper summarizes data concerning lateral wheel distributions and examines the advantages of extended (or widened) PCC slabs in terms of their effect on stress, strain, deflection, and PCC pavement deterioration. Widened slabs are increasingly used by many highway agencies due to their beneficial effect on pavement performance. Present wheel load distribution was determined to be an average of 50 to 55 cm (20 to 22 inches) away from the edge stripe on 4.6-m (12-ft) shoulders. Detrimental edge loads were found to be reduced significantly at 40 to 50 cm (16 to 20 inches) away from the PCC slab edge. A PCC slab widened 45 to 60 cm (18 to 24 inches) and striped with a 12-ft lane can expect a 20- to 30-percent increase in pavement fatigue life.
Shoulder design practices have been surveyed and synthesized in this report. General design information is summarized for the shoulder types used by the SHAs, including cross section design data. Similar performance problems have been noted from various highway agencies, particularly in the sealing and maintenance of the longitudinal joint between a concrete pavement and a bituminous shoulder.
This study evaluated the effects of widened slabs and tied concrete shoulders on the performance of PCC pavements. Three test sections were constructed on I-70 in 1994 consisting of a widened PCC slab with tied PCC shoulder, a widened PCC slab with nontied PCC shoulder, and a standard-width PCC slab with tied PCC shoulder. After construction, these sections were instrumented with dial gauges and surface-mounted strain gauges to measure the temperature and load-induced deflections and strains. Follow-up testing was conducted with the FWD after 1 year to evaluate the structural response of the pavement sections. Results from the investigation indicated the development of a built-in negative temperature gradient such that the pavement is actually curled up at a zero temperature gradient. Furthermore, some separation of the PCC slab from the AC base apparently is occurring due to significant differences in the theoretical and measured responses. An analysis of the amount of slab widening to obtain structural benefits revealed that a 6-m (2-ft) widening is appropriate.
This guide suggests methods for material selection, moisture control, and compaction or treatment of soils and materials to ensure volume stability and uniform support for concrete pavement. Various environments are considered and appropriate methods of subgrade preparation are outlined. Subbase functions are defined and adaptability of types of subbase are discussed. Placement of materials to aid in subbase moisture control is emphasized in shoulder design. A section on recognition of causes of deficiencies in existing pavements is included to alert the engineer to the consequences of improper construction or adverse environment.
This manual provides practical guidance on soils inspection, characterization, and strength testing for pavement design purposes. Among the topics covered are the AASHTO and Unified soil classification systems, pedologic soil classification, and the California Bearing Ratio, plate bearing (k value), resistance (R value), and resilient modulus tests.
The primary purpose of this manual is to provide background information for engineers responsible for utilizing soil stabilization as an integral part of a pavement structure. The importance of materials properties is discussed, and guidelines provided on the selection of an appropriate stabilizer to use with specific soil types. Construction procedures and equipment for each stabilization method also are described. Information is also included to assist the engineer in evaluating the drainage problems of a pavement. Specific details of drainage design, including permeable base design, are given, along with guidelines on the construction of drainage systems.
This report documents a comprehensive study on the effect of structural support conditions on the performance of PCC pavements. An exhaustive review of the characterization of subgrade support in PCC pavement design is presented, along with an examination of the causes of loss of support beneath PCC slabs. The report also documents several major deficiencies related to concrete pavement support that were found to exist in the current AASHTO design procedure. It was determined that the commonly used "top-of-the-base" k value is unrealistically high. The static, elastic k value of the foundation (subgrade and, if present, fill) is considered the appropriate k value for use in concrete pavement design. Guidelines are provided for three methods for determining k value for design: (1) correlation methods; (2) deflection testing and backcalculation methods; and (3) plate load testing methods.
A three-dimensional finite-element model was developed to analyze the effects of foundation support, base properties, joint spacing, slab thickness, climate, and other factors on concrete pavement performance. The stress analysis results were combined with the AASHO road test stress-performance correlation to develop a proposed revision to the AASHTO rigid pavement design model.
Several important issues concerning the effect of slab support on concrete pavement performance were studied under NCHRP Project 1-30. However, the data available for testing and validating the results generated by that study were limited. This study was conducted to further field-verify and develop the improved support guidelines proposed in NCHRP 1-30 using the LTPP database to establish their practicality and appropriateness for use in concrete pavement design nationwide. This study was also conducted to further field-verify the proposed revisions to the AASHTO rigid pavement performance model using the design, materials, traffic, and performance data available in the LTPP database for rigid pavements. Guidelines, revised on the basis of this field verification study, are presented in the appendix in the form of a proposed addendum to the AASHTO design guide. Complete documentation on the field verification efforts is included.
Construction over problem soil areas requires extensive site investigations, environmental impact studies, and detailed comparative design analyses to evaluate possible construction alternatives. These investigations are expensive, but the costs are more than offset by the potential savings in construction costs, avoidance of environmental problems, improved pavement performance, reduced maintenance costs, and so on. A number of construction alternatives are available for treating problem soils, and the characteristics, benefits, limitations, and costs of these alternatives are described in detail. Factors to be considered in selecting an appropriate construction alternative are also provided.
Highway engineers in seasonal frost areas have been aware for decades of the damaging effects that frost in the underlying support layers can have on pavement performance. Pavement heaving and cracking resulting from frost action and thaw-induced breakups are familiar problems. In the highway environment, the factors of climate, soil, water, pavement structure, and traffic are known to interact in freezing and thawing situations to the detriment of the pavement. The exact nature of the physical processes that take place, the sensitivities of the several contributing factors, and the magnitude of the responses to freezing action are not well understood. Nevertheless, usable criteria exist and are reported in this synthesis for identifying frost susceptibility, and for selecting measures that will avoid harmful pavement reaction.
This report describes and assesses the merit of current roadway design practice in seasonal frost areas. Information is presented on the mechanisms of frost heaving and thaw weakening, the factors that contribute to frost problems, criteria for estimating frost susceptibility, surveying practices for locating areas of detrimental frost action, subgrade treatment and drainage to minimize the effects of frost action, and the structural design of pavements to accommodate the influences of frost action. In addition, it identifies research needs in the area.
This synthesis is intended to provide information to engineers and other transportation officials on methods to evaluate and improve subgrade conditions to meet the constructibility requirements of a reconstruction project. Information was gathered through the use of a questionnaire sent to 65 transportation agencies in the United States and Canada and by a review of pertinent literature. A number of laboratory and in situ testing methods for evaluating subgrade soil properties are presented. In addition to traditional methods of laboratory testing of subgrade soils (e.g., Proctor compaction and California Bearing Ratio (CBR)), there appears to be an increased reliance on nondestructive methods such as the FWD for subgrade evaluation of existing pavements. Furthermore, the dynamic cone penetrometer appears to have great potential for evaluating subgrade stability before, during, and after pavement construction. Detailed information is also presented on the current use of drainage systems (including edge and lateral drains, drainage layers, and geotextile filters) as well as common remediation measures for solving subgrade problems.
This introduction to soil properties and characteristics emphasizes how those soil properties influence the design, construction, and performance of concrete pavements. Traditional soil tests, such as Proctor moisture-density tests, triaxial compression test, CBR test, stabiliometer test, and plate load test, are completely described with discussion on the practical meaning and application of each test. Recommended procedures for conducting detailed soil surveys and performing representative soil sampling are also described, highlighted by examples illustrating soil survey and analysis procedures in various highway applications.
The importance of subgrade support evaluation in the design, analysis, and construction of concrete pavement has been demonstrated. Subgrade soil strength and stiffness properties significantly influence the structural response (concrete pavement stresses, surface deflection) and the performance of concrete pavement systems. Moisture and temperature are the major climatic parameters that influence soil strength and stiffness. The effects of moisture and temperature factors on fine-grained soil behavior are documented. The necessity of considering spatial and seasonal variability in subgrade support is emphasized. Techniques for predicting temperature and moisture conditions in pavement systems are described.
Many significant engineering properties of soils are beneficially modified by lime treatment. Although lime is primarily used to treat fine-grained soils, it can also be used to modify the characteristics of the fine fraction of more granular soils, to expedite construction, modify subgrade soils, and improve strength and durability of subgrade soils. This document presents the state-of-the-art in lime treatment of paving materials, including a description of the soil-lime reactions, a summary of the properties and characteristics of lime-treated soils, and recommended guidelines for the design and construction of soil-lime mixtures.
This document provides construction engineers and technicians with information on all aspects of earthwork construction. Although not intended as a design manual, it does contain considerable background information on the design concepts necessary for good earthwork construction. Most sections contain information on specific field problems, and a number of references are included to provide engineers with additional detailed information. Earthwork topics included in this guide are compaction, earthwork construction, drainage, embankment foundations, earthwork for retaining structures, environmental considerations, special soil deposits and embankment materials, and instrumentation for embankments.
The testing and construction details of nine test sections with varying textural characteristics are described. The effects of the textures on the frictional and noise characteristics of the pavement surface were examined. Skid numbers were acquired according to ASTM E274 with ribbed and smooth tires at 65, 80, and 105 km/hr (40, 50, and 65 mi/hr) for all sections. Six types of texture-measuring devices were used to measure and compare the amount of texture in each section. To examine the noise properties of the test sections, noise data were required in three locations: inside the vehicle, 7.6 m (25 ft) from the centerline, and near the right rear tire of the vehicle. The smooth tire showed more sensitivity to micro- and macrotexture than the ribbed tire, and is recommended as the means of acquiring skid numbers. The sand patch test to measure texture depth showed excellent correlations to smooth-tire skid numbers and is also recommended. Finally, longitudinal textures were found to be much quieter than transverse textures.
This report documents the noise properties and the frictional characteristics of various concrete pavement textures. It describes the testing and construction details of nine test sections with varying textural characteristics. Included is an overview of the methodologies used to texture concrete pavement surface and a discussion of frictional attributes of various surface textures at different speeds and their impact on noise properties. There is also a description of the state-of-the-art equipment used toacquire sound pressure levels, texture-measuring devices and texture installing equipment, plus a discussion of data acquisition.
Crash rates were compared between 290 km (180 mi) of continuously ground and 115 km (71 mi) of transversely tined PCC pavements in Wisconsin. All 11,219 reported crashes at the study sites during the 6-year period (1988 to 1993) were analyzed. Continuously ground surfaces were found to have lower crash rates than tined surfaces under dry and wet conditions during daytime and nighttime as well as under all four combinations of pavement and light conditions. Ground pavements had 58 percent the crash rates of tined pavements under dry and wet conditions; the ratio was 84 percent when snow or ice was present on the pavement; however, relatively limited vehicular travel occurred under such conditions and these results are viewed as preliminary. Ground pavements had 57 percent the crash rates of tined pavements during daytime, and 73 percent at night. On the basis of the available data, a hypothesis of increasing crash rates with time (based on frictional property deterioration with pavement age, cumulative vehicle passes since construction, or both) could not be confirmed for either type of pavement texture.
The annoying noise frequencies produced from tire/pavement interaction on some (usually transverse tined) PCC pavements have concerned both nearby residents and traveling motorists. A Technical Working Group (TWG) was formed to investigate the problem by conducting a review of previous research and by evaluating the results of ongoing research. The goal of the TWG was to recommend PCC pavement surface textures that will reduce the annoying noise frequencies without compromising safety.
Noise-reducing construction methods that work most effectively for new pavements are to randomly space (10 to 40 mm (0.4 to 1.6 inch)) the transverse tines/grooves, construct longitudinal tines/grooves (either according to AASHTO guidelines or to the Spanish plastic brushing method), or construct an exposed aggregate surface. Existing PCC pavements that produce an annoying noise should be retextured (diamond grooving, diamond or carbide grinding, or shotblasting) or resurfaced (PCC overlay or surface laminate, microsurfacing, or a dense- or open-graded asphalt concrete overlay).
Twelve PCC pavement test sections were constructed to compare with standard PCC pavement and AC pavement to quantify the effects of the pavement surface texture on noise, safety, and winter maintenance. Asphalt pavements studied include an SHRP asphalt, stone matrix asphalt, and Wisconsin standard asphalt. A dependency between the pavement textures and their noise characteristics was observed. Noise measurements indicated that uniformly transversely tined PCC pavement created dominant noise frequencies that were audible adjacent to the road and inside the test vehicles. However, careful design and construction of transversely tined PCC pavement can reduce tire-road noise. No significant acoustical advantages of open-graded asphalts over the standard dense-graded asphalt were found.
This paper represents the second phase of a project researching the texture and noise characteristics of PCC pavements. Ten new PCC pavements were built on Highway 29 east of the 1994 Phase I test sites and evaluated; re-evaluations were also conducted on previously evaluated sections in North Dakota, Minnesota, Iowa, Colorado, and Michigan. Interior and exterior noise was measured using the Fast Fourier Transform (FFT) method with a Larson-Davis tow channel real time acoustical analyzer. Texture on all sites was measured with the Road Surface Analyzer (ROSAN). Sand patch tests were also performed.
Generally, the longitudinal tined PCC and asphaltic concrete (AC) pavements exhibited the lowest exterior noise levels. No significant advantage was found regarding exterior noise levels for special textures such as the European, Skidabrader, or diamond ground PCC pavements. The lowest interior noise levels were those of the longitudinal, skewed, European PCC, and AC pavements. The ROSAN mean profile depth and estimated texture depth correlated very closely with the sand patch and friction measurements, especially when analyzed with a certain texture type.
A TWG representing SHAs, industry, academia, and FHWA met over a 3-year period to update guidance on methods to obtain high pavement surface friction values while minimizing tire/pavement noise. The TWG reviewed the current guidance on surface texture as it relates to safety (friction and vehicle control including effects of splash and spray), noise (inside and outside of the vehicle), drainage (cross slope, effect of longitudinal and transverse tining, and other surface textures), durability, ride (profile), texture quality (measurement), and economy of construction. This paper summarizes the findings as well as the recommendations of the TWG.
Pavement/tire noise has been studied for well over 30 years; several large databases have been compiled in the past decade. This synthesis is a summary of the research findings on this extensively studied topic. Summaries of selected sample sets are included to allow comparisons of the results and reports. Because the reporting is voluminous, care was taken to include up-to-date reports and those that summarize ideas from groups of individuals. In addition, a survey of current practices was conducted to help guide the synthesis.
This report summarizes current and past research and development work related to surface texturing technology. It begins with experiments on skid resistance in the early 1930s in Iowa and Ohio and carries up through the recent developments in exposed aggregate and porous concrete in Europe. Reports and publications are summarized on the work done in this field in the past 60 years with emphasis on concrete pavement friction and tire/road noise issues. Various surface texturing techniques discussed in this report include burlap dragging, transverse tining, longitudinal tining, exposed aggregate, chip sprinkling, surface dressing, and porous.
