Concrete for pavements has historically been specified and field controlled around acceptance criteria that do not relate well to durability (slump, air content, strength). Paving concrete specifications need to be built upon engineering properties that directly relate to good field performance. With the recent advancements in research knowledge on failure mechanisms, and the paralleled development of better tests, this is possible. A review of many current and new specifications has found that they are still largely based on strength, slump, and air, which provide limited correlation with the mechanisms of pavement failure currently observed. The need for change in the way we specify concrete, especially concrete for paving mixtures, is becoming increasingly apparent as mixtures become more complex with a growing range of chemical admixtures and supplementary cementitious materials. Traffic loadings continue to increase, more aggressive winter maintenance practices are implemented, and demand increases to build systems more quickly, cheaply, and with increased longevity. The Federal Highway Administration, through their Cooperative Agreement with the National Concrete Pavement Technology Center, has been working with the 30 member-state departments of transportation of the National Concrete Consortium to identify the specification approach and key testing technologies that are needed for paving concrete to have increased durability, including in the presence of wet freeze thaw and winter deicing materials. The testing technologies have been developed, and the next critical activities are deployment of the new testing technologies, development of practical specifications and QA/QC recommendations, and correlating specification limits with durable field performance. It is proposed that a TPF supported financially and technically by FHWA, DOTs, and industry be advanced as the best approach to accelerating the implementation and benefits associated with durability based specifications. To date two significant milestones have been accomplished: 1. During the late summer of 2015 and the 2016 paving season, agencies (Illinois, Indiana, Iowa, Nebraska, Michigan, Minnesota, Wisconsin, South Dakota, Manitoba, and the Illinois Tollway) have started using and evaluating new testing technologies that support the design and testing of performance engineered concrete paving mixtures (PEMs). 2. A proposed AASHTO provisional specification and commentary has been submitted for balloting by the member states. The specification seeks to provide agencies with the tools to prepare a specification for concrete mixtures for pavements that moves closer to measuring and basing acceptance on the parameters that are truly critical to the long-term performance of the system. The commentary is provided to support each relevant section of the specification to provide background information and the rationale behind the recommended approach. Discussion is provided in this commentary regarding how desired performance requirements are typically sought in a prescriptive specification for comparison between the recommendations in this document and current practice. It is recommended that mixing performance and prescriptive approaches be avoided, to the degree possible, because of the risk of making it impossible to meet all of the demands on the system. The intent of this TPF is to build upon these two critical steps and provide technical assistance and training to participants, validate the AASHTO provisional specification based upon actual field performance, and continue the developmental work of measuring and relating early age concrete properties to pavement performance.

The objective of this study is to focus on the successful deployment of performance engineered mixtures. This will involve building off the foundational work that FHWA and the “PEM Champion States” have done, with emphasis on implementation, education and training, adjusting the specification values to relate accurately to good pavement performance in the field, and continued development of relating early age concrete properties to performance.

See solicitation document for full details of study scope. Task 1: Implementing What We Know This task is intended to provide support to study participants with implementation of performance engineered paving mixtures within their states. Task 2: Performance Monitoring and Specification Refinement With any new specification it is critical to monitor the requirements and be sure that they are optimized to consistently produce good performing pavements. As necessary, the specification values and testing limits should be adjusted to represent the optimal balance between cost and performance. This task will provide field performance data for use in making decisions on specification limits in the areas of salt damage, transport and freeze-thaw damage. To accomplish this successfully, an organized process of pavement monitoring and evaluation is intended in this task. It is proposed that the projects built under PEM specification requirements also continue to be monitored in the future Phase 2 of the study. Task 3: Measuring and Relating Early Age Concrete Properties to Performance This task will build upon the foundational work done to date in measurement technologies to design and control concrete pavement mixtures around key engineering properties. It is planned that work under this task will address Improved testing methods for improved accuracy and reduced cost.

• Proposed start: January 1, 2017 • TPF length: 5 years (Phase 1)* Proposed Funding Sources • DOT’s: $15,000 per year for 5 years ($75,000) from 14 states. $1,050,000 • FHWA: $200,000 per year for 5 years = $1,000,000 • Industry: $200,000 per year for 5 years = $1,000,000** *Phase 2 (2022-2026) Future • The specific scope will be developed in detail in year 4 of the Phase 1 study, but at a minimum it is envisioned that Phase 2 will have continued emphasis on Tasks 2 and 3 of Phase 1. **Industry commitments will be made through a dedicated fund established by the CP Tech Center to support this project. Work on the project is anticipated to start once the first-year funding of $600,000 is committed. Summary of Requirements for Project Sponsors: 1. Financial support 2. Participation in quarterly TAC meetings, three of which will be web based and one physical meeting per year. DOT travel support will be provided through the TPF. 3. Participate in implementation of a PEM specification through test evaluation, shadow projects, and pilot projects. 4. Assistance with performance monitoring data collection to ensure specification limits reflect actual field performance. The Iowa DOT will serve as the lead state for the accomplishment of the pooled fund project described in this proposal. The Iowa DOT, through the National Concrete Pavement Technology Center (CP Tech Center) at Iowa State University, will handle all administrative and technical duties associated with the project. The CP Tech Center will serve as the lead research institution for the project, with Oklahoma State University and Oregon State University as contributing institutions. The Co-Principle investigators will be Dr. Peter Taylor for Iowa State University, Dr. Tyler Ley for Oklahoma State University, and Dr. Jason Weiss for Oregon State University.