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Advanced Concrete Pavement Technology (ACPT) Program-A Status Report on Available Products

Chapter 4: Promising ACPT Products in Detail

Introduction

This section presents details on each promising ACPT product identified in Chapter 3.

ACPT Program Focus Area 1: Advanced Designs

FA1-1: Mechanistic-Empirical Concrete Pavement Design (MEPDG)

Development of the MEPDG was sponsored by NCHRP under Project 1-37A. Initiated in 1996, the project developed a comprehensive approach to the design of pavement structures, with formal documentation produced in 2004 and ongoing refinements to the accompanying software program culminating in the release of version 1.0 in 2007.

Primary benefits of the new design guide are the improved reliability of the resultant designs and the ability to handle any and all combinations of materials, traffic, and climatic conditions. The current released version of the software is being implemented by many U.S. highway agencies. The implementation activities include characterizing locally available/used construction materials and developing local calibrations for the performance models used in the software.

There is a continuing need to support highways agencies with the implementation activities related to the MEPDG. The support can include workshops on the MEPDG, topical presentations, as well as development of best practices techbriefs.

Timeline for product delivery: Immediate
Product availability: AASHTO, State DOTs

FA1-2: Concrete Overlays Design

The need for optimizing preservation and rehabilitation strategies used to maintain the Nation’s highway pavements has never been greater. Concrete overlays have a long history of use to preserve and rehabilitate concrete and asphalt pavements, and many of the practices are well established. However, of recent origin are techniques that use thinner concrete overlays with shorter joint spacing. Field experience over more than 15 years with the thinner concrete overlays under a range of traffic and site conditions has demonstrated their viability as a cost-effective solution to extend the service life of deteriorated asphalt and concrete pavements.

A current gap in concrete overlays technology is the absence of nationally validated rational design procedures for thin-bonded and unbonded concrete overlays of existing asphalt concrete and composite pavements. The availability of a rational design procedure will encourage many highway agencies to consider use of thin concrete overlays as alternates for rehabilitation of asphalt and composite pavements. Work is currently underway at the University of Illinois and University of Pittsburgh to develop improved design procedures for bonded concrete overlays.

Timeline for product delivery: Within 24 months
Product availability: NCPTC/University of Illinois, FHWA Pooled Fund Study

FA1-3: Concrete Pavement Design Catalogs

There has been continued interest in the development of concrete pavement catalog-based design procedures. These procedures typically use simple tabular format for establishing pavement designs and consider the key design parameters, such as traffic level and base/subbase/subgrade support condition. Design details, such as joint spacing, dowel bar use, use of a widened outside lane or a tied concrete shoulder are fixed. The Europeans use the design catalogs extensively for low-level as well as high-level roadways. The catalogs are based on field experience, theoretical analysis, and field and laboratory testing and are reviewed and modified, as necessary, on a 5-to-10-year cycle.

The MEPDG, when fully implemented, will involve a level of complexity that many highway agencies may not be able to respond to on a routine basis. As such, there will be a need to implement a simplified version of the MEPDG for routine pavement design determination. As part of the implementation of the new MEPDG, several highway agencies are expected to develop catalog-based design procedures. The industry, including ACPA, is also pursuing the development of design catalogs for concrete pavement design.

Timeline for product delivery: Within 24 months
Product availability: AASHTO MEPDG, State DOTs, European Catalogs,

FA1-4: Advanced Concepts for Joint Design

Considerable work has been performed recently to improve the performance of joints in concrete pavements. This work can be classified as follows:

  1. Dowel bar material-corrosion resistant
    1. Corrosion-resistant steel (e.g., MMX)
    2. Clad steel bars
    3. Nonmetallic bars
    4. Advanced dowel bar coatings
  2. Dowel bar design-shape (cross section), cross-sectional area (diameter), length, spacing
  3. Impact of dowel misalignment on joint performance
  4. Joint-sawing requirements
    1. Width of sawing
    2. Depth of sawing
    3. Timing of sawing
  5. Need for a second sawcut (sealant reservoir)
  6. Joint-sealing requirements
  7. Tie-bar design for longitudinal joints

There is a need to develop best practices guidance based on findings from recently completed studies and based on newly implemented practices at several U.S. highway agencies.

Timeline for product delivery: Immediate
Product availability: State DOT specifications, NCHRP, FHWA

FA1-5: Optimizing Design Features and Life Cycle Costs

Recently, a CPTP project (CPTP Task 6) resulted in a process to evaluate the tradeoffs between performance benefits of design enhancements in concrete pavements and the costs of these added features. The process and the associated software are good educational tools for users who want to better understand concrete pavement design and its impact on construction costs and performance. There is a need to provide further refinement to the process by incorporating the analytical features and findings from detailed parametric studies using the MEPDG and using FHWA’s RealCost software.

Timeline for product delivery: Within 24 months
Product availability: AASHTO MEPDG, State DOTs, FHWA RealCost software

FA1-6: Innovative Design Procedures for Concrete Pavements (CRCP, Prestressed, Precast, RCCP)

The MEPDG addresses primarily the needs for jointed concrete pavements. However, there is a need to provide better guidance to stakeholders for the design of CRCP, precast pavements, and RCCPs. Source material is available for the design of these pavement types.

In addition, there is work underway in South Africa related to design and performance of very thin CRCP and in Chile for design and performance of thin jointed concrete pavements. These innovative practices need to be evaluated and, if applicable, refined for application to U.S. conditions.

The available information and assessment need to be integrated in a single best practices compendium of design procedures for these different pavement types that have not been directly incorporated in the MEPDG. The compendium will identify the key steps and parameters to consider when designing these pavements.

Timeline for product delivery: Within 24 months
Product availability: FHWA, Industry, Non-U.S. research organizations

ACPT Program Focus Area 2: Improved Construction Materials

FA2-1: Optimizing Use of Recycled Materials

Recycled aggregates (RA) are produced from the processing of previously used construction materials, such as concrete. Recycled aggregate is routinely used for highway pavement construction in the United States. The principal application of RA has been as a base material. However, the use of RA as aggregate in new concrete is not as widely accepted. This is primarily due to concerns related to the durability of concrete that includes RA. As raw aggregate materials become scarce or more expensive, it is important that the use of RA be optimized, especially for use in concrete. When used in concrete, RA is typically blended in with raw aggregates.

The use of recycled concrete continues to grow as an increasing number of agencies are showing renewed interest in this technology. However, the full benefit of this technology, particularly as it relates to various sustainability factors, has yet to be realized, and the state of the technology needs to be synthesized and presented in a practice-ready implementation package, including guidelines and test protocols for evaluating the project-specific RA.

Timeline for product delivery: Immediate
Product availability: FHWA, industry, State DOTs

FA2-2: Advanced High-Performance Materials

As good construction material sources become scarce or more expensive, there will be a need to develop and use advanced high-performance materials (HPMs) in the construction of new and rehabilitated pavements. The HPMs can be classified as follows:

  1. New materials to replace current materials that are in short supply (irrespective of cost).
  2. New materials that perform similarly to conventional materials but are less expensive.
  3. New materials that result in longer service life (irrespective of cost).
  4. New materials that meet our needs for sustainable solutions (smaller carbon footprint, conservation of resources, carbon sequestering, etc.).
  5. New materials that improve the properties of marginal materials.
  6. Waste and recycled materials that are optimized for use in highway pavement construction.

There is an urgent need to develop a white paper on HPMs in highway construction. The knowledge base on HPMs must be developed as a matter of national urgency as the availability of HPMs is expected to be critical in the future for designing and constructing longer lasting pavements that meet user expectations related to ride and safety.

Timeline for product delivery: Immediately
Product availability: Industry

FA2-3: Concrete Mixture Optimization

Concrete mixture design requires the consideration of a wide array of aggregate sources, cement sources and types, chemical admixtures, supplementary cementitious materials, and recycled materials. The designer must also consider the interaction of ingredients within the mixture and how a given environment may affect the construction and the long-term performance of the pavement. With the emphasis on accelerated construction and long-lasting pavements coupled with a wider variety of materials options, concrete mixture optimization has become more challenging than ever. Recently, as part of the CPTP, a mixture optimization software, COMPASS, and guidelines were developed that simplify the concrete mixture design and proportioning process based on job-specific conditions. In addition, significant effort is underway to develop advanced concrete mixture optimization procedures under the CP Road Map’s Mixture Design track. These new concrete mixture design procedures are expected to result in better performing concrete that optimizes use of locally available materials, including RA.

Timeline for product delivery: Immediately, with refinements to be made as additional products come on line.
Product availability: FHWA, NCPTC, industry

FA2-4: Concrete Durability

It is well accepted that concrete pavement failure should be a result of structural failure due to traffic and environmental loadings. Concrete pavement failure should not be a result of premature failure of the concrete itself. The best means of maximizing the probability that concrete will be durable is to produce concrete that will provide the desired service for the environment in which it will be placed and used. Exposure to freezing and thawing, sulfates, and deicing chemicals should be considered when selecting materials and proportions. In addition, available materials must be selected to prevent excessive expansion due to ASR and alkali-carbonate rock reaction. The fundamental factor in creating durable concrete is optimizing the use of supplementary cementitious materials (pozzolan and ground granulated blast-furnace slag) and chemical admixtures in combination with cement and the proper use of combined aggregate gradation. In the last 10 years, significant progress has been made in improving our understanding of concrete material- related distresses, and test protocols have been developed to identify marginal materials. More work is underway as part of the CP Road Map initiatives and through State DOT and industry sponsorship. There is a need to develop a best practices implementation package that provides guidance and includes test protocols that will ensure that nondurable concrete will be a thing of the past.

Timeline for product delivery: Within 24 months
Product availability: FHWA ASR Program, NCPTC, State DOTs, industry

FA2-5: Concrete Testing

Concrete testing is an important part of the QC and QA testing at concrete pavement construction projects. Currently, the following gaps exist in routine testing of concrete:

  1. Lack of a concrete workability test. The slump test is used as a surrogate test to estimate workability, but the slump test only provides information related to concrete consistency from batch to batch. A good workability test can help ensure that concrete that is deposited in front of a slipform paver can be placed, consolidated, and finished without much additional hand manipulation of the concrete.
  2. Lack of tests for freshly placed and consolidated concrete behind the paver. There is a need to determine the air content (and air void characteristics) and concrete consolidation in freshly placed concrete.

Work is underway to develop rapid test procedures for determining workability of concrete on the basis of concrete rheology and for rapid evaluation of the air system and consolidation of freshly placed concrete. The findings from these studies need to be disseminated to the concrete pavement stakeholder as soon as possible.

Timeline for product delivery: Within 24 months
Product availability: Industry

ACPT Program Focus Area 3: Improved Construction Processes

FA3-1: Improved Processes for Construction Process Control and Acceptance Testing

For the most part, concrete pavement process control and product acceptance testing (QC and QA) is performed using processes developed more than 50 years ago. Most of the testing on fresh concrete is performed before concrete is placed, and little testing of fresh concrete is performed behind the slipform paver. In addition, testing of hardened concrete typically requires a destructive test, requiring cores from the hardened concrete.

The contractor is required to perform a series of tests to ensure that he is not delivering marginal concrete to the project site and that the construction process will not produce a pavement that is deficient. The owner also performs a series of test to ensure that the end product delivered (the concrete pavement) will result in long-term service as per design expectations. The owner’s tests typically include concrete strength, concrete thickness, concrete “quality,” and pavement ride. Dowel alignment and pavement surface texture are important specification requirements, but acceptance testing for these items is typically not performed as the means to perform these tests have not been readily available.

Recently, progress has been made with regard to evaluating dowel bar alignment in freshly placed concrete using a device based on magnetic tomography. A device developed in Germany, MIT Scan, has been introduced in the United States under CPTP. Many agencies are investigating the applicability of the MIT Scan device either as part of the contractor’s process control or as part of the owner’s acceptance testing. In addition, another similar device, MIT Scan T2, has also been introduced in the United States under CPTP. This device accurately measures slab thickness nondestructively, eliminating the need for cores to determine slab thickness. Work is in progress to develop an improved version of the air void analyzer system to measure the air system of freshly placed concrete. Also, work is continuing to improve nondestructive testing procedures, such as the Impact Echo procedure, to reliably estimate in-place concrete strength. In addition, FHWA-developed software systems such as HIPERPAV and PROVAL are expected to play an important role in improving contractor process control operations.

The most up-to-date information on improved test methods (equipment, software, and protocols) for concrete pavement construction needs to be made available to agencies and industry in a timely manner.

Timeline for product delivery: Immediately.
Product availability: FHWA, industry

FA3-2: Performance-Related and End-Product Specifications

PRS are an outgrowth of current end-result, QA specifications. In highway construction, PRS are defined as specifications for key materials and construction quality characteristics that have been demonstrated to correlate significantly with long-term pavement performance. PRS include sampling and testing procedures for acceptance quality characteristics along with acceptance or rejection criteria. A major feature of PRS is the development of rational pay adjustments based on the projected performance of the pavement.

FHWA has been promoting the development and implementation of PRS since the 1980s. A model PRS was developed in the mid-1990s and has been employed on several trial projects in several States. As more agencies and contractors become familiar with the PRS methodology, the approach is expected to lead to higher quality construction that is more cost effective and that incorporates innovative construction methods. The end result will be longer-lasting pavements.

The evolvement of PRS is expected to continue, with future work looking at, among other things, the development of improved performance models based on the MEPDG and the use of nondestructive acceptance testing procedures for as-placed concrete and concrete pavement. A recently initiated FHWA study is expected to result in a significantly improved PRS model that can be easily implemented by highway agencies.

Timeline for product delivery: Within 24 months
Product availability: FHWA, State DOTs

FA3-3: Improving Concrete Pavement Performance and Sustainability Through Two-Lift Construction

Two-lift concrete pavement construction offers a number of innovative opportunities to improve concrete pavement performance and sustainability. The lower lift can be optimized to make the best use of locally available or recycled materials, whereas the top lift can be optimized for long life and functionality (improved safety and lower tire-pavement noise levels) under high traffic loading. It is reasonably simple and cost effective to use two very different concrete mixture designs to achieve increased economic and environmental benefit while also achieving maximum social value. Two-lift construction is a common practice in many European countries. In the United States, a two-lift pavement test section was constructed in 1992, and efforts are underway to re-introduce this concept. A two-lift test section was constructed in Kansas in 2008. The use of two-lift concrete pavements is being investigated by several agencies, especially when there are direct economic advantages in adopting this technology. The full benefit of this technology has yet to be realized, and the state of the technology, as improved, needs to be synthesized and presented in a practice-ready implementation package. A more aggressive technology transfer effort is needed to showcase this very promising technology in the United States.

Timeline for product delivery: Immediately
Product availability: State DOTs, European highway agencies, industry

ACPT Program Focus Area 4: Rapid Repair and Rehabilitation (of all pavement types)

FA4-1: Rapid Pavement Condition Evaluation

Hundreds of miles of concrete pavement need to be rehabilitated every year due to rapidly declining pavement condition. A critical decision that needs to be made as part of the rehabilitation strategy relates to timing of the rehabilitation, and this decision depends on objective evaluation of the condition of the concrete pavement. Concrete pavement condition evaluation includes structural evaluation as well as evaluation of the concrete material- related distress (MRD). Good techniques are available for performing project-level structural evaluation based on deflection testing and condition surveys. However, good protocols do not yet exist to assess the durability of the concrete. For example, for pavements affected by ASR or D-Cracking, there are no definitive protocols to determine the right time to perform rehabilitation. Many concrete pavements continue to provide good service for many years after initiation of the MRD; on the other hand, many pavements rapidly deteriorate after initiation of the MRD.

There is a need to provide tools to rapidly perform structural evaluation as well as MRD evaluation of concrete pavements. Much work has already been performed, and many studies are underway. The FHWA ASR Program is expected to provide better test protocols to evaluate the state of ASR-related damage in concrete and to help estimate the remaining service life of affected pavements.

Timeline for product delivery: Within 24 months
Product availability: FHWA, industry

FA4-2: Rapid Rehabilitation and Reconstruction of High-Volume Facilities

Pavement rehabilitation and reconstruction, major activities for all U.S. highway agencies, have significant impact on agency resources and traffic disruptions because of extensive and extended lane closures. The traffic volumes on the primary highway system, especially in urban areas, have increased tremendously over the last 20 years. This has resulted, in many instances, in an earlier-than-expected need to rehabilitate and reconstruct highway pavements. Highway agencies continue to wrestle with the age-old problem: longer delays now and longer service life versus shorter delays now and shorter service life. In recent years, agencies have been investigating alternative strategies for pavement rehabilitation and reconstruction that allow for faster yet durable rehabilitation and reconstruction of pavements.

Accelerated construction, which minimizes construction impact on the driving public, is being implemented by many highway agencies that allow the use of concrete for rehabilitation and reconstruction of deteriorated pavements, both concrete and asphalt. Accelerated construction optimizes use of pavement design, available concrete materials, construction practices, and traffic management strategies to construct long-life concrete pavements. A key feature of accelerated construction is the recognition that pavement rehabilitation and reconstruction under traffic does not provide for longer lasting pavements and actually requires more extended lane closures with consequences on travel times and user and construction worker safety. Contractors typically prefer better management of the construction zones that include full road closure. Full closures are being achieved using three strategies: nighttime, weekend, and extended closures. At the CPTP conference on accelerated construction held in Atlanta, Georgia, in 2007, several highway agencies discussed their practices and future directions. The discussion at the conference indicated that there is a real need to develop guidance on accelerated construction and rehabilitation of concrete pavements. There is a need to synthesize the best procedures currently being used by agencies and to develop improved guidance for undertaking accelerated rehabilitation and reconstruction.

Timeline for product delivery: Within 24 months
Product availability: State DOTs, FHWA, industry

FA4-3: Precast Panels for Repair

Precast concrete pavement technology is an innovative process that can be used to meet the need for rapid repair and rehabilitation of asphalt and jointed concrete pavements. Precast pavement technology is ready for implementation. Precast pavement systems are fabricated or assembled offsite, transported to the project site, and installed on a prepared foundation (existing or regraded). The system components require little or no field curing time to achieve strength before opening to traffic. These systems are primarily used for rapid repair and rehabilitation of asphalt and PCC pavements in roadways with high-volume traffic. The precast technology can be used for intermittent repairs or full-scale, continuous rehabilitation. In intermittent repair of PCC pavement, isolated full-depth repairs at joints and cracks or full-panel replacements are conducted using precast concrete slab panels. The repairs are typically full-lane width.

Performance of the installed panels, though short in terms of time, indicates that precast pavement systems have the potential for providing rapid repairs that will be durable. The installation of precast pavements has a higher first cost. However, the rapid application that minimizes lane closures and the long-term durability may easily offset the higher initial costs. In the last 5 years, many highway agencies have begun using precast panels for intermittent repairs of jointed concrete pavements. However, there is still some reservation on the part of many highway agencies with regard to implementing this new technology because of higher costs and the lack of performance data. A study currently underway in the SHRP 2 Rapid Renewal Area is expected to develop improved guidance for design, fabrication, and installation of precast panels for intermittent repairs. In addition, many agencies have developed specifications for use of precast panels for repair applications. Recently, a techbrief on this subject was developed under FHWA’s CPTP.

The available information needs to be disseminated to highway agencies, precasters, and general contractors. The increase in use of this technology is expected to result in lower costs and improved processes.

Timeline for product delivery: Immediately, with refinements incorporated based on findings from the SHRP 2 study.
Product availability: FHWA, industry

FA4-4: Precast Panels for Reconstruction and Rehabilitation

Precast concrete pavement technology comprises new and innovative construction methods that can be used to meet the need for rapid pavement repair and construction. Precast pavement technology is ready for implementation. Precast pavement components are fabricated or assembled offsite, transported to the project site, and installed on a prepared foundation (existing pavement or regraded foundation). The system components require minimal field curing time to achieve strength before opening to traffic. These systems are primarily used for rapid repair, rehabilitation, and reconstruction of both asphalt and PCC pavements in high-volume-traffic roadways. The precast technology can be used for intermittent repairs or full-scale, continuous rehabilitation. In continuous applications, full-scale, project-level rehabilitation or reconstruction of both asphalt and PCC pavements is performed using precast concrete panels. One technology developed for continuous applications is PPCP. It is based on the experience gained from several cast-in-place prestressed concrete pavement projects constructed during the 1980s in the United States.

Use of precast concrete pavements for reconstruction and rehabilitation is a viable alternative to conventional cast-in-place concrete pavement construction, especially in situations where high traffic volumes and consideration of the delay costs to users due to lane closures favor reconstruction and rehabilitation solutions that allow expedited opening to traffic. Precast concrete also offers the advantage of being “factory made” in a more controlled environment than cast-in-place construction and thus is potentially more durable and less susceptible to construction and material variability.

In the last 5 years, many highway agencies have begun implementing or investigating the use of precast panels for continuous applications. However, there is still some reservation on the part of many highway agencies with regard to implementation of this new technology because of higher costs and the lack of performance data. A study currently underway in the SHRP 2 Rapid Renewal Area is expected to develop improved guidance for design, fabrication, and installation of precast panels for continuous application. In addition, many agencies have developed specifications for use of precast pavement for pavement reconstruction application. Recently, a techbrief on this subject was developed under FHWA’s CPTP.

The available information needs to be disseminated to highway agencies, precasters, and general contractors. The increase in use of this technology is expected to result in lower costs and improved processes.

Timeline for product delivery: Within 24 months
Product availability: FHWA, industry

FA4-5: Innovative Repair and Rehabilitation Processes

Most concrete pavements exhibit distress after many years in service, and these pavements need to be repaired to extend the service life of these pavements while providing safe and smooth ride for the users. Conventional practices for repair are well established, and these procedures involve repair materials, equipment for installing repairs, and proper techniques to ensure long-lasting repairs. Since most repairs are performed under difficult traffic conditions and restricted site access, many repairs do not perform well. There is a need to use materials, equipment, and techniques that provide a higher reliability with respect to repair performance. The processes should be ”failure-proof.” The industry continues to make advances in developing improved processes for repairing concrete pavements. However, there is no effective process to compile information on what works and what does not as new repair processes are developed. There is a need to develop a library of case studies based on State DOT experience with new repair processes.

Timeline for product delivery: Immediately
Product availability: Industry, State DOTs

FA4-6: Construction Traffic Management

The need for well-planned construction traffic management is very important, particularly on high-volume freeways in urban areas, because of the need to minimize traffic disruptions and travel delays associated with lane closures during pavement rehabilitation or reconstruction. Pavement construction and rehabilitation in urban areas almost always requires the use of accelerated construction techniques that minimize the impact of construction on the travelling public. Accelerated construction work done under traffic places a burden on both the highway agency and contractor to produce a high-quality pavement while minimizing traffic delay and maximizing traffic safety. In some cases, the option of a long-life pavement is ruled out for such projects because of concerns related to user delays and safety. Over the last 10 years, much effort has been focused on developing tools that allow highway agencies to evaluate and optimize construction traffic management strategies.

A popular software for this application is CA4PRS (Construction Analysis for Pavement Rehabilitation Strategies), developed at the University of California at Berkeley. FHWA has encouraged use of CA4PRS for pavement rehabilitation projects. AASHTO has also endorsed wider use of the software. Other new tools are being developed that will allow contractors and highway agencies to analyze different construction traffic management strategies prior to construction, allowing them to select the optimal traffic management strategy. The best practices and the best analytical tools for analysis of construction traffic management strategies need to be made available to agencies and contractors.

Timeline for product delivery: Within 24 months
Product availability: Academia, AASHTO, industry

ACPT Program Focus Area 5: Sustainable Concrete Pavements

A number of concrete pavement products are emerging in the materials and sustainability area that are deployable and implementable. Some of these products have emerged after years of research and are finally at a stage where they can be employed with confidence. Others are techniques that have been used elsewhere in the world for over a decade, most notably in Europe, and are now ready for acceptance in the United States. Consistent with the Concrete Pavement Sustainability Track in the CP Road Map, the products are described here.

FA5-1: Sustainable Pavement Designs

There is a need to extend initial concrete pavement service life beyond 40 years with little maintenance or repairs. This can be accomplished through the incorporation of certain design features as well as the use of durable materials. The contribution to sustainability of extended life has been presented in an ad-hoc basis through publication of few articles but needs to be better documented and disseminated.

Timeline for product delivery: Immediately
Product availability: FHWA, NCPTC, State DOTs, industry

FA5-2: Sustainable Use of Construction Materials

It is well documented that, for conventional concrete mixtures, the production of portland cement is overwhelmingly the largest contributor of energy consumption and emissions generated associated with concrete production, accounting for roughly 80 percent of the total energy consumed and 90 percent of the CO2 emissions. Thus, a reduction in portland cement content, by replacing the cement with supplementary cementitious materials (SCMs) or reducing the total cementitious content through optimized aggregate grading, will have very positive effects on the sustainability of concrete pavement.

Multiple studies are underway or have been recently completed by various agencies to increase the usage of SCMs and reduce the total cementitious content in concrete by using an optimized aggregate gradation. The CP Road Map Track 13: Sustainable Concrete Pavements is focusing considerable attention on developing guidance on how to reduce the portland cement content in transportation concrete. Work being conducted on CP Road Map Track 13 will result in a briefing document during 2009 that will detail the state of the practice and identify future projects. A manual of practice will be completed within during 2010.

Timeline for product delivery: Within 24 months
Product availability: FHWA, NCPTC, State DOTs, industry

FA5-3: Sustainable Construction Practices

Increasingly, the environmental and social impacts of pavement construction are being recognized, as increased truck traffic, emissions and particulates, noise, and congestion all negatively impact the surrounding communities. Further, the construction process itself consumes vast amounts of resources, generates considerable waste, and uses significant quantities of water. As a result, a number of studies are underway to improve the sustainability of concrete pavement construction through better management of construction traffic, reduction of construction wastes, and better management of water. All elements of the construction process need to be considered.

Concerns regarding the sustainability of the concrete pavement construction process continue to grow as a number of local and State agencies are showing increasing interest in this technology. The full benefit of considering this technology has yet to be realized, as the information needs to be synthesized and presented in a practice-ready implementation package.

Timeline for product delivery: Immediately
Product availability: FHWA, NCPTC, State DOTs, industry

FA5-4: Sustainable Repair and Rehabilitation Processes

Timely and appropriate repair and rehabilitation will ensure that a concrete pavement will achieve the extended service life that is expected. Designing and constructing concrete pavements to anticipate restoration in 30 to 50 years-for example, by adding nominal additional thickness to accommodate diamond grinding-enhances pavement life and functionality at little additional initial cost. The sustainability of such practices will be enhanced by recognizing the importance of the life cycle, where consideration of repair and rehabilitation will reduce economic and environmental costs over the extended service life.

Although many projects have been completed on concrete pavement repair and rehabilitation, the information needs to be synthesized to capture new technology, particularly as it pertains to sustainability. Deployment and implementation efforts will focus on the accurate anticipation and timely execution of the appropriate treatment, as this is paramount to reducing cost and extending pavement life.

Timeline for product delivery: Immediately
Product availability: FHWA, NCPTC, State DOTs, industry

FA5-5: Catalog of Sustainable Concrete Pavement Practices

Sustainability is becoming an important consideration in all pavement management decisions, yet it is unclear exactly what is meant by the term and how sustainability of concrete pavements can be improved. The concrete paving industry has suggested sustainable features to be incorporated in concrete pavement design and construction, but little specific guidance is provided. The CP Road Map Track 13 on Sustainable Concrete Pavements is working on establishing a framework document to guide research and implementation into the future.

There is an urgent need to catalog the current state of the practice to improve concrete pavement sustainability and to disseminate this information to the industry, so as to achieve an immediate increase in understanding and improvement of concrete pavement sustainability.

Timeline for product delivery: Immediately
Product availability: FHWA, NCPTC, State DOTs, industry

FA5-6: Environmental Life Cycle Analysis Tools

One of the most critical challenges facing us is to understand how to quantify and compare the environmental benefits and impacts of various engineering solutions as is done in Europe. There is a need to adopt a quantification process that is robust and unbiased, allowing the identification of desirable solutions while creating the synergy needed to promote these solutions. Such a process must also be flexible enough to allow for the consideration of a broad category of alternatives, including those that contain innovative features. The quantification process does not assume that one strategy is better than another, but allows comparison of one type of solution to another over a broad range of environmental considerations. The effort conducted under this category is at the heart of advancing sustainability of concrete pavements through adoption of a life cycle analysis (LCA) approach.

An LCA requires the assembling of available data to create and maintain a concrete pavement specific life cycle inventory (LCI) with local/regional North American data. The data would include values assigned to materials and processes for impact categories such as embodied energy (both primary and feedstock), global warming potential, water (use, reuse, and treatment), noise, airborne particulate, emissions, human toxicity, etc. The LCI would also assign ranking of the significance of the impact categories for all the materials and processes used in the design, initial construction, maintenance, restoration, rehabilitation, and recycling of the pavement. In accordance with European practice, the LCA protocol must adhere to international standards such as those described in the International Organization for Standardization’s 14000 standards, and must be accessible to the concrete pavement community as a tool or toolkit in an easily usable format to help improve the sustainability of concrete pavements. The technology to advance this important tool currently exists, and it is simply a matter of deployment and implementation.

Timeline for product delivery: Immediately
Product availability: FHWA, NCPTC, State DOTs, industry

ACPT Program Focus Area 6: Enhanced User Satisfaction

FA6-1: Innovative Pavement Surface Texturing for Safety and Noise Reduction

Pavement surface characteristics (functional properties) except smoothness are not typically addressed on current projects except by method specifications. The recently published AASHTO Guide for Pavement Friction, the NCHRP 1-43 Final Research Report, the 2005 FHWA Technical Advisory on Surface Texture, the proposed FHWA Technical Advisory update on the Skid Accident Reduction Program, and the proposed 2009 publication of the Highway Safety Manual should all generate need for enhanced evaluation procedures for pavement surface texture and project-specific guidance.

There is a critical need to reduce the annual number of fatalities and serious injuries on our Nation’s highways. Safety of the traveling public and pedestrians should be a very high priority goal. Guidance on friction and texture for new and rehabilitated PCC pavements will help accomplish this goal. Since pavement surface texture affects both pavement-tire noise and surface friction (safety), surface texture issues need to be considered by assessing impact on both noise and safety.

Improved guidelines are needed in the following areas:

  1. PCC surface texture design and construction techniques-selection guidelines.
  2. Methods and equipment to evaluate PCC friction, noise, and texture-laboratory and field techniques.
  3. PCC friction and noise performance prediction models and monitoring procedures.
  4. Guide Specifications for PCC Pavement Macro-texture.

Timeline for product delivery: Immediately
Product availability: FHWA, NCPTC

FA6-2: Techniques to Improve Pavement Ride

Research by FHWA, other highway agencies, and industry is ongoing to improve concrete pavement ride quality and support FHWA’s national goal to significantly improve pavement smoothness on the National Highway System. The research is aimed at resolving the following specific issues unique to concrete pavements:

  • Construction factors that affect the smoothness of concrete pavements.
  • Proper procedures to measure the smoothness of pavements for construction acceptance using inertial profilers including profiler equipment factors that influence measurements.
  • Objectionable profile characteristics that are created during paving and how such features can be identified from profile data.
  • How texture and joints affect measurements made by inertial profilers.
  • The lower limit of IRI beyond which road users will not be able to able to detect an improvement in smoothness.
  • The relationship between the ride quality deterioration rate and the initial smoothness of a pavement.
  • A procedure to detect and correct localized roughness features from profile data.
  • The effect of a localized roughness feature on the dynamic loads that are applied on the pavement.

The findings from recently completed CPTP studies and ongoing studies will help improve our understanding of the concrete pavement profile characteristics that impact user satisfaction with ride quality and will help to develop rational procedures to measure the profile characteristics of interest.

Timeline for product delivery: Within 24 months
Product availability: FHWA, NCPTC

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Updated: 04/07/2011

FHWA
United States Department of Transportation - Federal Highway Administration