Early-age behavior of CRCP and its implications for long-term performance
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Continuously Reinforced Concrete Pavement (CRCP) is the most widely used rigid pavement type in Texas. The advantages of CRCP over other rigid pavement types include the absence of transverse contraction joints. With the increased use of CRCP, a vast amount of information has been collected on design variables and their effects on CRCP performance. Most advanced CRCP designs use the mechanistic-empirical approach. In this approach, structural responses of CRCP due to environmental and traffic loadings are computed. Damage to concrete is estimated over time, and pavement distress is predicted using empirically derived distress models. The reliability of the current CRCP design procedures depends, to a large extent, on the accuracy of the empirically derived distress models. The primary objective of this study is to identify the “cause and effect” relationship between early-age CRCP behavior and longterm performance, thereby improving the accuracy of the distress prediction models. In the first phase of this study, a detailed analysis was conducted on the environmental loads in CRCP at early ages – temperature and moisture variations in vii concrete. Temperatures in concrete were evaluated using thermochron devices; moistures were evaluated using various devices. In the next phase, early-age behavior of CRCP in terms of concrete and steel strains and stresses due to environmental loading was extensively investigated. Stress independent and total strains in concrete were measured using vibrating wire gages in several test sections; concrete stresses were calculated from the measured strains. Steel strains were also measured using resistance type gages and steel stress calculated. A methodology to estimate in-situ zero-stress point was developed and applied to calculate in-situ zero-stress points in several test sections. In the final phase of the study, CRCP behavior in terms of crack spacing and crack width was monitored for three years. Current theories on CRCP distress mechanisms and their limitations were critically reviewed and improvements needed are suggested. Efforts were made to identify relationships between early-age CRCP behavior and long-term pavement performance. It is expected that the findings from this study will help improve the accuracy of the CRCP distress mechanisms and make CRCP design algorithms more mechanistic-based and accurate.