Iowa Department of Transportation
Peter Taylorptaylor@iastate.edu email >
Director, CP Tech Center
About the research
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 parallel 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.
The objective of this study is to focus on the successful deployment of performance engineered mixtures. This involves building off the foundational work that the Federal Highway Administration and the “PEM Champion States” have done, with emphasis on implementation, education and training, adjustment of the specification values to relate accurately to good pavement performance in the field, and continued development of relating early age concrete properties to performance.