Advanced Concrete Pavement Technology (ACPT) Program-A Status Report on Available Products
Chapter 2: ACPT Technology Activities
This section presents a summary of the broad range of efforts underway by many agencies and industry organizations to improve concrete pavement technology.
Concrete Pavement Technology Program
CPTP, initiated in 2001 and completed in 2009, was a national program of research, development, and technology transfer that operated within the Office of Pavement Technology of FHWA. The focus of the program was on implementing improved methods of designing, constructing, evaluating, and rehabilitating PCC pavements to promote cost-effective designs and long-term performance for Federal-aid highways. Four goals were established for the CPTP early in its development, reflecting critical needs within the area of concrete pavements:
- Reduce user delays.
- Reduce costs.
- Improve performance.
- Foster innovation.
These goals addressed the needs of the State DOTs, the concrete pavement industry, and the highway user, while supporting FHWA's strategic goals to improve the mobility, productivity, and safety of the Nation's highway system by developing longer lasting, better performing pavements with safer, smoother rides and reduced congestion caused by construction work zones.
The CPTP initiative encompassed a broad range of projects, ranging from materials research to field testing of new technologies, from the development of computer programs to the implementation of technology transfer activities. For purposes of categorization, the CPTP initiative was divided into six focus areas relating to various aspects of concrete pavements (Tayabji and Smith 2004):
More than 30 projects, referred to as tasks, were included in these focus areas, and each was closely tied to the overall goals and objectives of the program. A summary of the key products developed under CPTP is given below:
Focus Area 1: Advanced Designs: Projects in this area studied ways to improve or advance pavement structural designs. Key products include the following:
- Improved procedures for design of whitetopping overlays.
- Status of high-performance concrete pavements.
- Alternative dowel bars for load transfer in jointed concrete pavements.
- Guidelines for determining need for transverse joint sealing.
- AASHTO provisional specification on determination of concrete coefficient of thermal expansion (CTE).
Focus Area 2: Improved Materials: Projects in this area studied ways to improve or advance concrete material selection processes and concrete mix design procedurs to result in durable concrete paving mixes that can be placed and finished effectively for slipform operations. Key products include the following:
- Guidelines for identifying incompatible combinations of concrete materials.
- Improved guidelines for optimizing project-specific concrete mixtures.
- Improved procedures for evaluating concrete durability.
Focus Area 3: Improved Construction Processes: In this focus area, CPTP projects studied the use of new or innovative equipment and technologies for improving all aspects of concrete pavement construction. Key products include the following:
- Guidelines for construction traffic management.
- Enhanced software programs for managing concrete paving (HIPERPAV II).
- Field evaluations of performance-related specifications (PRS).
- Field demonstrations of new testing equipment and technologies (e.g., MIT Scan devices).
- Guidelines for concrete curing.
Focus Area 4: Rapid Repair and Rehabilitation: Projects in this area studied ways to improve or advance concrete pavement rehabilitation technologies that would allow for faster and more durable repair and rehabilitation/reconstruction of concrete pavements. Key products include the following:
- Guidelines for repair of ultrathin whitetopping.
- Guidelines for rapid urban concrete pavement reconstruction.
- Precast pavement for full-depth repair of concrete pavements.
- Precast pavement for asphalt concrete and concrete pavement rehabilitation and reconstruction.
- Improved guidelines and strategies for concrete pavement rehabilitation.
- Improved guidelines for concrete pavement restoration techniques.
Focus Area 5: Enhanced User Satisfaction: In this focus area, the CPTP projects were aimed at increasing user satisfaction by reducing congestion and improving functional performance. Key products include the following:
- Guidelines on pavement surface texturing.
- Pavement Profile Viewer and Analyzer (ProVAL 2.0) software.
- Determination of the effect of materials properties on pavement smoothness.
- Guidelines for specifying and constructing pavements that are smooth and have good long-term performance.
Focus Area 6: Trained Work Force: CPTP Focus Area 6 was directed at ensuring that appropriate training was made available in a timely manner. The principal products of Focus Area 6 were the development, integration, and presentation of training for various aspects of the CPTP.
Concrete Pavement Road Map
The CP Road Map is a 10-year, innovative, strategic plan that outlines the use of approximately $250 million in needed concrete pavement research. Published in late 2005, the Road Map's official title is “Long-Term Plan for Concrete Pavement Research and Technology.” The CP Road Map was developed under FHWA’s CPTP Task 15 and is currently administered by the National Concrete Pavement Technology Center (NCPTC), based at Iowa State University in Ames. The CP Road Map combines more than 250 problem statements into 13 integrated research tracks. Each track has specific goals and a path for reaching the goals. The tasks are listed below:
- Performance-Based Concrete Pavement Mix Design System.
- Performance-Based Design Guide for New and Rehabilitated Concrete Pavements.
- High-Speed Nondestructive Testing and Intelligent Construction Systems.
- Optimized Surface Characteristics for Safe, Quiet, and Smooth Concrete Pavements.
- Concrete Pavement Equipment Automation and Advancements.
- Innovative Concrete Pavement Joint Design, Materials, and Construction.
- High-Speed Concrete Pavement Rehabilitation and Construction.
- Long-Life Concrete Pavements.
- Concrete Pavement Accelerated and Long-Term Data Collection.
- Concrete Pavement Performance.
- Concrete Pavement Business Systems and Economics.
- Advanced Concrete Pavement Materials.
- Concrete Pavement Sustainability.
The concept for funding projects under the CP Road Map is that stakeholders will voluntarily align opportunities to pool funds and intellectual resources in ad hoc research collaborations. As an example, State agencies are providing support for the Road Map by joining FHWA pool-funded studies to support several high-priority projects. Currently (as of March 2009) the following activities are in progress (NCPTC 2009):
- Performance-Based Concrete Pavement Mix Design System.
- Performance-Based Design Guide for New and Rehabilitated Concrete Pavements.
- Optimized Surface Characteristics for Safe, Quiet, and Smooth Concrete Pavements.
- Concrete Pavement Business Systems and Economics.
- Concrete Pavement Sustainability.
The Alkali-Silica Reactivity Program
SAFETEA-LU Section 5203 (e) established funding for furthering the development and deployment of techniques to prevent and mitigate ASR. Funding was provided for $10 million over 4 years. The ASR Development and Deployment Program (ASRDDP) activities were initiated during 2005 (FHWA 2009a). The ASRDDP includes research activities as well as field demonstration projects. As part of the field program, FWHA will make funding available to States for the implementation of technologies and techniques to prevent and mitigate ASR. Currently, it is anticipated that field trials can be implemented by the end of 2009.
One of the tasks under ASRDDP is the development of three ASR protocols, targeted to assist State highway agencies with their ASR problems. The three protocols are as follows:
- Protocol A: Determining the Reactivity of Concrete Aggregates and Selecting Appropriate Measures for Preventing Deleterious Expansion in Concrete.
- Protocol B: Diagnosis and Prognosis of Alkali-Aggregate Reaction in Transportation Structures.
- Protocol C: Selection of Mitigation Measures for Alkali-Aggregate Reactive-Affected Structures.
The research projects initiated during 2008 include the following:
- Objective 1: Advancing the fundamental understanding of the ASR mechanism and developing a concrete mixture design process that is resistant to the ASR phenomenon.
- Objective 2: Developing a reliable, improved, rapid laboratory test method to evaluate concrete mixture design to predict field performance.
- Objective 3: Nondestructive field test methods for evaluation of concrete structures for the presence of ASR to determine concrete deterioration rates and predict future expansion.
- Objective 4: Develop cost-effective methods to control ASR and extend the service life of existing highway structures.
In the past few years, FHWA has entered into three cooperative agreements with outside agencies to advance concrete pavement design and construction technologies in support of the CPTP:
- Technology Transfer of Best Practices for Concrete and Concrete Pavements-American Concrete Institute (ACI). This agreement will provide education and training activities for FHWA’s customers and partners, including the following deliverables:
- Training materials for seminars, workshops, and conferences, including a training syllabus and related materials needed by State DOTs to prepare their inspectors for the ACI Transportation Inspector Certification test; and updates of materials used in FHWA-sponsored seminars.
- Seminars and related training activities for State DOTs, FHWA field offices, and members of the concrete industry.
- Conferences for the highway community, including the coordination of a process for FHWA’s participation in and funding of up to three conferences per year.
- Advancement of Continuously Reinforced Concrete Pavement Through Technology Transfer and Delivery of Industry Guidance for Design and Engineering-Concrete Reinforcing Steel Institute. Products of the ongoing agreement include technical guides addressing the design, construction, and repair and rehabilitation of CRCP that are available for review and implementation by highway agencies. Deliverables include the following:
- A strategy for technology transfer of CRCP guidance, including a national communications plan to develop a shared sense of purpose among all of FHWA’s partners and customers in the States, the concrete pavement industry, and related supplier groups.
- Conferences, seminars, and workshops for those stakeholders.
- A strategy for assisting State DOTs in accepting and implementing industry guidance for design and engineering of CRCP.
- Advancement of the Precast Prestressed Concrete Pavement System Through Technology Transfer and Development of Industry Guidance for Design and Engineering-Precast-Prestressed Concrete Institute. This agreement will encourage timely acceptance and technically sound implementation of precast prestressed concrete pavement (PPCP) as a proven alternative pavement system. It includes the following deliverables:
- A strategy for technology transfer on the PPCP system in the agency/owner and industry communities, including preparation and distribution of informational flyers, videos, and technical reports.
- A strategy for industry guidance of design and engineering of the PPCP system, including organization of program activities among the agency/owner and industry communities through technical committee meetings and related activities.
FHWA Pavement Surface Characteristics Program
The FHWA Pavement Surface Characteristics (PSC) Program considers smoothness, friction, tire-
pavement noise, and splash/spray in an integrated manner. The PSC Program is aimed at improving the ride on the National Highway System and to provide pavement surface texture that meets the dual needs of highway safety and lower pavement noise. FHWA also anticipates starting work on an improved functional performance indicator.
FHWA has established ride targets for all National Highway System roads (FHWA 2009b). As of January 2009, these targets are an International Roughness Index (IRI) of 95 in/mi (or less) as the primary performance target, with the secondary performance target of 170 in/mi (or less).
With respect to improving ride quality, FHWA-sponsored activities include development and delivery of customized pavement smoothness workshops, improved pavement smoothness specifications using inertial profilers, advanced pavement profile analysis software (ProVAL), and use of advanced profile measurement technology (ultra-light inertial profiler).
With respect to pavement surface texture, current work sponsored by FHWA is focused on addressing noise-related issues. These activities include improved pavement/tire noise-measurement techniques, comprehensive program of data collection and analysis on new and existing pavements, splash and spray reduction, and development of innovative texturing techniques that have the potential to significantly reduce noise.
Office of Pavement Technology Projects
In addition to FHWA’s program initiatives, a number of activities are being conducted by the FHWA Office of Pavement Technology, including the following:
- Pavement Design and Analysis Support-Provide assistance to State highway agencies for implementation of the Mechanistic-Empirical Pavement Design Guide (MEPDG). The assistance will include various products for implementation of this new design procedure including deployment of innovative equipment, materials, tools, and techniques as well as working with partners to improve pavement design, performance, and rehabilitation.
- Materials and Construction Technology Support-Evaluate and refine innovative materials and construction techniques that will provide a durable long-life pavement and develop strategies for deploying these technologies to state highway agencies on active field projects. Several of the research products from FHWA’s Turner-Fairbank Highway Research Center, such as HIPERPAV, CTE, and SmartCure, will be refined through on-site demonstrations to State highway agencies. Other technologies to be evaluated include air void analyzer testing, MIT SCAN evaluation of dowel bar alignment, and pavement thickness as well as other emerging technologies as a result of Track 2 of the CP Road Map.
- Quality Assurance Program Effectiveness-Provide State DOTs with guidelines for the implementation of both quality control (QC) procedures and quality assurance (QA) in an effort to advance the state of the practice for those tests that affect the long-term performance of pavements during the mixture design, mixture verification, and construction phases of a project. This project will build upon the results of the 17-State pooled-fund study, "Material and Construction Optimization for Prevention of Premature Distress in PCC Pavements," which resulted in a testing guide for QC procedures. This activity will collect data on actual field projects, demonstrate appropriate quality control techniques for ensuring a quality product, and stress other factors that affect the long-term durability of concrete pavements beyond measuring compressive strength.
- Coefficient of Thermal Expansion of Concrete-Conduct a study of as many current users of manual and Gilson CTE devices as possible to determine the differences in CTE measurements as well as the variability in the different CTE devices. FHWA is soliciting State DOT laboratories and university research centers with the CTE equipment capability to conduct CTE testing of three specimens for this study. It is anticipated that at least 15 laboratories will participate. This exercise would yield enough information to determine within-lab and between-lab variability for the CTE devices. The study is not aimed at determining precision and bias for the AASHTO TP 60 test method. It is intended to obtain some understanding of the variability in CTE test results with various measuring devices.
Turner-Fairbank Highway Research Center Activities
The TFHRC, in McLean, Virginia, oversees federally funded research and conducts research in several areas of highway technology, including concrete pavement design and performance. Among the studies on concrete pavements currently being overseen by TFHRC are the following:
- Long-Term Pavement Performance (LTPP) program. An ongoing program that involves evaluation of pavement performance at hundreds of pavement test sections that include concrete pavements. Data collected from these test sections are being used to improve pavement design, construction, and rehabilitation practices.
- Refining PPCP technology for slab replacement under bridges. This study is aimed at addressing a research need identified in FHWA's National Concrete Pavement Road Map (FHWA Report No. HT-05-053). Design details for precast, post-tensioned slabs will be refined and tested in the laboratory.
- Evaluating the NCHRP 1-37A rigid pavement performance models. This study involves examining the predictions obtained from the MEPDG software developed under NCHRP 1-37A for cracking, faulting, spalling, punchouts, and IRI for concrete pavements.
- Evaluating lithium-based methods for mitigating ASR in concrete and documenting the benefits of the most promising methods.
- Developing a system for monitoring pavement properties using embedded sensors. This study will develop a sensor system for continuously monitoring both the early-age and long-term physical properties of concrete or asphalt pavements.
- Enhancing the current computer-based guidelines for concrete pavements (HIPERPAV III). This study will add new features to the HIPERPAV software, including improved sensitivity analysis capabilities, enhanced curing and moisture-transport prediction capabilities.
- Incorporating the MEPDG prediction models for jointed plain concrete pavement (JPCP) into the PaveSpec PRS software. This effort will produce a new version of the PaveSpec software and user manual and provide guidance to State DOTs on developing both job-specific and statewide PRS for JPCP.
- Integrating software to optimize design, construction, evaluation, and performance of concrete pavements. Software products to be considered for integration under this contract include PaveSpec, SpecRisk, Prob.O.Prof (Probabilistic Optimization for Profit), COMPASS, HIPERPAV, and SAPER, which have undergone various degrees of implementation.
- Determining the application of second-generation fiber-reinforced polymer (FRP) technology to pavements. This study is investigating and developing two FRP applications in concrete pavements-FRP dowels for JPCP and FRP rebars for CRCP.
- Expanding, improving, and upgrading Prob.O.Prof. Prob.O.Prof is a software tool that can be used by contractors to help decide what quality levels to target under QA specifications and by highway agencies to help validate their specifications. The new version (Prob.O.Prof 2.0) is improved and has been expanded to cover other PCC paving acceptance quality characteristics, several State specifications, and asphalt paving.
State Department of Transportation Initiatives
Several State DOTs maintain an active program of research related to concrete pavements to meet specific local needs. The research may be conducted in-house, awarded to local universities, or contracted to outside organizations. Examples of concrete pavement-
related research programs at State DOTs include the following:
- Evaluation of dowel-bar retrofit strategy
- Development and implementation of a mechanistic-empirical pavement design procedure for rigid and flexible pavements in California
- Quieter Pavement Research Program-Concrete Pavements
- Continued refinement of simulation software for constructability analysis-CA4PRS (Construction Analysis for Pavement Rehabilitation Strategies)
- Long-life concrete pavement design (JCP and CRCP)
- Sustainable concrete pavements
- PCC durability
- Dowel bar performance at JPCP Joints
- Quiet and smooth PCCP
- Abrasion-resistant PCCP
- Nondestructive testing for pavement thickness determination
- Precast concrete pavement use for rapid repair and rehabilitation
- Thin concrete overlays over existing concrete pavements
- Implementation of the AASHTO MEPDG
- Performance of precast prestressed roadway slabs
- Performance of PCC inlay
- TR-505 Improving Portland Cement Concrete Mix Consistency and Production Rate Through Two-Stage Mixing
- TR-520 Evaluation of Dowel Bar Retrofits for Local Road Pavements
- TR-587 Impact of Low Shrinkage Mixes on Late-age Random Cracking in Pavements With Use of Early Entry Sawing
- TR-600 Improving Concrete Overlay Construction
- Development of Performance Properties of Ternary Mixes, Phase I
- Self-Consolidating Concrete-Applications for Slip Form Paving, Phase 2
- Development of an improved specification for maximum plastic concrete temperatures (study at the University of Illinois)
- Improve the Life Expectancy of PCCP Using Low Permeability Concrete Mixtures
- MnRoad test sections (Phase II studies)
- Unbonded concrete overlays
- Pervious concrete pavement and overlay
- PCCP surface characteristics-construction- and rehabilitation-related
- High-performance concrete pavement
- SHRP 2 composite pavement study
- Thin whitetopping design procedure (pooled-fund study)
- Quiet concrete pavements using an innovative diamond-grinding process
- Application of intelligent compaction
- Thin unbonded concrete overlay with geo-fabric interlayer
- Using cement paste rheology to predict concrete mix design problems
- Use of manufactured sands for concrete paving (at University of Texas)
- Precast pavement applications for rapid rehabilitation of concrete pavements
- Implementation of MEPDG
- Improved mix designs to reduce studded tire wear
Many State DOTs also participate in the FHWA-coordinated Transportation Pooled Fund (TPF) Program that allows Federal, State, and local agencies and other organizations to combine resources to support transportation research studies. The current TPF studies related to concrete pavements are listed in Table 1:
National Cooperative Highway Research Program
Administered by TRB and sponsored by the member departments of AASHTO (i.e., individual State DOTs) in cooperation with FHWA, the National Cooperative Highway Research Program (NCHRP) conducts research in acute problem areas that affect highway planning, design, construction, operation, and maintenance nationwide. NCHRP-sponsored projects have resulted in many improvements in concrete materials and concrete pavement technology over the last 40-plus years. Projects recently completed, ongoing, and planned for 2009 that are of interest to the ACPT program include the following:
- NCHRP 1-40B-User Manual and Local Calibration Guide for the Mechanistic-Empirical Pavement Design Guide and Software. The objective of this project is to prepare (1) a user manual for the MEPDG and software and (2) a detailed, practical guide for highway agencies for local or regional calibration of the distress models in the MEPDG and its accompanying design guide software. The manual and guide will be presented in the form of draft AASHTO recommended practices; the guide will contain two or more examples or case studies illustrating the step-by-step procedures.
- NCHRP 1-40D (02)-Technical Assistance to NCHRP and NCHRP Project 1-40A: Versions 0.9 and 1.0 of the M-E Pavement Design Software. The objectives of this project are to (1) work in coordination with the contractor for Project 1-40D(02) to produce improved, corrected versions 0.9 and 1.0 of the M-E Pavement Design Guide software and (2) provide ongoing troubleshooting support for NCHRP and FHWA.
- NCHRP 1-44-Measuring Tire-Pavement Noise at the Source. The objectives of this research are to (1) develop rational procedures for measuring tire-pavement noise and (2) demonstrate applicability of the procedures through testing of in-service pavements.
- NCHRP 1-46-Handbook for Pavement Design, Construction, and Management. The objective of this research is to develop a handbook that addresses design, construction, and management aspects of pavements. The Handbook shall be prepared in an interactive-electronic, easily editable format with a printer-friendly option, suitable for consideration and adoption by AASHTO.
- NCHRP 1-47-Sensitivity Evaluation of MEPDG Performance Prediction. The objective of this research is to determine the sensitivity of the performance predicted by the MEPDG to variability of input parameter values. The research will deal with all types of flexible and rigid pavements included in the MEPDG. The research shall be conducted using the MEPDG software version available as of October 1, 2008.
- NCHRP 18-13-Specifications and Protocols for Acceptance Tests of Fly Ash Used in Highway Concrete. The objective of this research is to recommend potential improvements to specifications and test protocols to determine the acceptability of fly ash for use in highway concrete.
- NCHRP 21-09-Intelligent Soil Compaction Systems. The objectives of this research are to determine the reliability of intelligent compaction systems and to develop recommended construction specifications for the application of intelligent compaction systems in soils and aggregate base materials. Intelligent compaction involves the use of rollers that are equipped with a control system that can automatically adjust compactive effort in response to a materials modulus during the compaction process.
- NCHRP 04-36-Characterization of Cementitiously Stabilized Layers for Use in Pavement Design and Analysis. The objective of this research is to recommend performance-related procedures for characterizing cementitiously stabilized pavement layers for use in pavement design and analysis and incorporation in the MEPDG. The research will deal with material properties and related test methods that can be used to predict pavement performance. This research is concerned with subgrade, subbase, and base materials stabilized with hydraulic cement, fly ash, lime, or combinations and used in flexible and rigid pavements.
Strategic Highway Research Program 2
Congress established the second Strategic Highway Research Program (SHRP 2) in 2006 to investigate the underlying causes of highway crashes and congestion in a short-term program of focused research. To carry out that investigation, SHRP 2 has targeted goals in four interrelated focus areas:
- Safety: Significantly improve highway safety by understanding driving behavior in a study of unprecedented scale
- Renewal: Develop design and construction methods that cause minimal disruption and produce long-lived facilities to renew the aging highway infrastructure
- Reliability: Reduce congestion and improve travel time reliability through incident management, response, and mitigation
- Capacity: Integrate mobility, economic, environmental, and community needs into the planning and design of new transportation capacity
The renewal focus area has several studies that are looking at ways to extend the service life of existing concrete pavements as well as to accomplish rapid repair and rehabilitation of concrete pavements. The specific projects dealing with concrete pavements include the following:
- R05: Modular Pavement Technology. The objective of this project is to develop tools for public agencies to use for the design, construction, installation, maintenance, and evaluation of modular pavement systems. It is anticipated that these tools should include, at a minimum: a) guidance on the potential uses of modular pavement systems for specific rapid renewal applications; b) generic design criteria; c) project selection criteria; d) guidelines and draft or model specifications for construction, installation, acceptance, and maintenance; and e) a long-term evaluation plan to assess the performance of modular systems and lead to refinements in designs and materials.
- R06: A Plan for Developing High Speed, Nondestructive Testing Procedures for Both Design Evaluation and Construction Inspection. The overall objective of this work is to develop a process to identify existing or, if necessary, to develop new and quickly implementable technologies for rapid, nondestructive testing of in situ conditions for purposes of design, construction inspection, and performance monitoring. These technologies would limit or reduce traffic disruption on existing facilities during preliminary engineering investigations and provide more rapid and reliable information on as-built conditions. Similarly, rapid inspection of new construction would facilitate timely re-opening of roadways and structures during reconstruction.
- R06B: Evaluating Applications of Field Spectroscopy Devices to Fingerprint Commonly Used Construction Materials. The purpose of this project is to identify and evaluate practical hand-held equipment for quantitative analyses of applications such as the following (as applicable to concrete pavements):
- Quality and uniformity of curing compounds.
- Quality and uniformity of epoxy materials used for concrete spall repair.
- Quality and uniformity of cement and/or concrete.
An additional objective is to develop relatively simple and easy-to-use nondestructive procedures and protocols that inspectors and front-line personnel could use in the field to ensure quality construction.
- R06E: Real-Time Smoothness Measurements on Portland Cement Concrete Pavements During Construction. The purpose of this project is to enable real-time control of concrete pavement smoothness during construction by providing a) proven technologies for measuring smoothness in real time; and b) model specifications and guidelines for use by transportation agencies.
- R06F: Development of Continuous Deflection Device. The objective of this project is to critically assess the potential of existing continuous deflection devices as a practical and cost-effective tool for use in the development of optimum pavement rehabilitation strategies on rapid renewal projects.
- R07: Performance Specifications for Rapid Renewal. The objectives of this project are the following:
- Reduce the completion time of renewal projects while maintaining or improving quality.
- Encourage further innovation by reducing mandatory method requirements and defining the end products.
- Develop different specifications that can be used effectively in various contracting scenarios (design-bid-build, design-build, warranties, etc.).
- Develop recommendations on the transition to the use of these specifications (i.e., an implementation plan).
- Quantify relative shared risk between project owners (State DOTs) and contractors and between contractors and subcontractors through the use of warranties and guarantees and identify strategies to equitably manage and minimize the short- and long-term risk to all parties.
- R21: Composite Pavement Systems. This project will investigate the design and construction of new composite pavement systems, and not those resulting from the rehabilitation of existing pavements. The research will focus on two promising applications of composite pavement systems: a) an asphalt layer(s) over a PCC layer and b) a PCC surface over a PCC layer. Specifically this effort shall:
- Determine the behavior and identify critical material and performance parameters.
- Develop and validate mechanistic-empirical performance models and design procedures consistent with the MEPDG.
- Recommend specifications, construction techniques, and quality management procedures.
- R23: Using Existing Pavement in Place and Achieving Long Life. The objective of this project is to provide guidance to public agencies for achieving long-lived pavements, reducing construction time, and minimizing the impact to the public by utilizing existing pavement in place in a rapid renewal environment. Specifically this project will:
- Identify approaches for using existing pavements in-place for rapid renewal projects.
- Determine the advantages and disadvantages for each approach under different project conditions.
- Develop detailed criteria on when an existing pavement can be used in place, with or without significant modification.
- Identify practices and techniques to construct these types of pavements in a rapid renewal environment.
- Determine the optimal way to integrate the renewed pavement with adjacent pavements and structures.
- R26: Preservation Approaches for High Traffic Volume Roadways. The objective of this project is to develop guidelines on pavement preservation strategies for high traffic volume roadways that can be used and implemented by public agencies. A secondary objective is to identify promising preservation strategies for application on high traffic volume roadways that may not commonly be used and make recommendations for further research opportunities.
The industry continues to maintain an active program to support research in high-priority areas of interest to specific industry organizations. Industry research in concrete pavement technology is being carried out as follows:
- By the American Concrete Pavement Association (ACPA).
- By the Innovative Pavement Research Foundation (IPRF).
- By individual vendors of products (material and equipment).
ACPA research projects that have recently been completed include the following:
- Longitudinal Joint Requirements for Concrete Pavements (Phase II)-This project is re-evaluating the longitudinal joint tie bar system design process and developing an improved design procedure that accounts for the critical factors involved. During the development of the NCHRP 1-32 Design Catalog, several State, FHWA, and industry concrete pavement experts assembled to provide input into many details of concrete pavement design concluded that the “subgrade drag theory” was inadequate and should not be used for design purposes. Thus, there is no valid design procedure available, and an urgent need exists for improved design of tie bars that considers this past performance but provides a more rational way of designing the tie system between traffic lanes and lanes and shoulders. This will allow for a more reliable and optimal design for the many variations of site conditions (number of lanes, shoulders, base types, truck traffic levels, PCC mixes, pavement designs, and climates).
- Development of Robust and Practical Dowel Bar Guidelines for the Concrete Paving Industry-Alternative dowel bar designs can prove cost effective while at the same time increasing the performance of roads significantly. With the proliferation of widening and urban applications of jointed concrete pavements and overlays, guidance is needed to optimize dowel designs that can fit to “real world” constraints that may preclude the use of today’s typical sections. DowelCAD 2.0 aims to aid designers in analyzing the effects of various dowel bar configurations and types, and to provide guidance on means to make such alternate designs feasible. The models in DowelCAD are based on fundamental mechanistic equations of beam behavior and the dowel-concrete interaction including work by Timoshenko, Westergaard, Skarlatos, Friberg, Colley, and Humphrey and by Ioannides. The finite element method developed by Huang is also used to characterize more global slab behavior.
The IPRF-sponsored projects, directed at airfield applications but having application to the ACPT Program, include the following:
- Project 06-1-Concrete Mixes Using Flyash
- Project 04-8-ASR Mitigation Studies
- Project 04-6-Lithium Admixtures and Early-Age Properties of Production Concrete
- Project 03-8-Field Trial and Evaluation of Innovative Concrete Pavement Technologies or Practices for Airport Pavements
- Project 03-10-Selected Methods for Mitigating ASR in Affected Airfield Pavements
- Project 05-5-Concrete Mixes Using Ground Granulated Blast Furnace Slag
- Project 06-4-Demonstration Project: Study the Combined Aggregate Concepts of the ASTM C-1260 Test
- Project 05-02-Joint Load Transfer Efficiency-Concrete Airfield Pavements
- Project 05-03-Highway Materials for Airfield Pavement (Concrete)
The industry-sponsored research applicable to concrete pavement is typically of a proprietary nature. The research involves development of advanced construction materials, improved construction techniques, new testing equipment, and improved or new construction equipment.
International Research and Development Programs
The research activities in Canada, Europe, and Japan that are related to the ACPT Program are summarized below:
- Evaluation of pervious concrete pavement (Ontario).
- FHWA-Ministry of Transport Ontario quiet texturing project.
- Evaluation of dowel bar alignment using the MIT Scan (Ontario).
- Evaluation of precast concrete slabs for concrete pavement repairs (Ontario, Quebec).
- Use of galvanized steel as reinforcement for CRCP (Quebec).
- Various studies on ASR being conducted at several Canadian universities.
- Modie Slab precast concrete pavement (The Netherlands).
- Advanced design and construction procedures for CRCP (Belgium).
- Hexagonal shaped precast pavement for urban application (France).
- Improved catalog design procedures for new concrete pavements (Germany).
- Low-noise concrete pavement surface using exposed aggregate surface (Austria,
Belgium, the Netherlands).
- Higher strength concrete for pavement applications.
- Optimizing concrete pavement design features (Austria, Germany).
- Studies on ASR (Germany).
It should be noted that the Europeans have a different philosophy with respect to pavement design. The key differences with U.S. practices are the following:
- Use of field-proven catalog designs.
- Use of higher strength concretes.
- Use of thinner concrete slab.
- Use of a well-designed support system under the concrete slab.
- Routine use of widened outside lane and concrete shoulder in urban areas.
- Composite pavement performance-study of asphalt surface course with a continuously reinforced concrete base course.
- Application of precast reinforced concrete slab pavements at airports.
- Evaluation of the performance of porous concrete pavements in Japan.
- Structural design method of precast reinforced concrete pavement with consideration of concrete and steel fatigue.
- Ultrathin CRCP.
As noted in this section, a wide range of activities have recently been completed, are in progress, or will be initiated soon to continue to advance concrete pavement technologies. The promising products from these technologies will include software, draft standards, guide documents, and other technology transfer materials. A discussion of the promising technologies, for possible implementation under the ACPT Program, is presented in the next section.