Investigation of cracking process and aggregate interlock properties of JPCP cracks

The main objectives of this research are to investigate the cracking process of jointed plain concrete pavements (JPCP) and to investigate the shear load transfer through aggregate interlock of fully developed transverse cracks. A predictive model for JPCP in-plane tensile strength was developed based on computed maximum load for a JPCP slab described by the bilinear stress-crack width relationship of the concrete. The numerical computed tensile strength of slabs containing partial-depth surface cracks showed that the predicted maximum load is dominated by the first part of the stress-crack width relationship and that the concrete appears to be indistinguishable from a material with a linear relationship when excluding the tail end. The proposed model incorporates these phenomena and excellent agreement was obtained between predicted and measured slab strengths for JPCP concrete mixes described by different stress-crack width relationships. The proposed model can be used in the development of fracture analysis of midslab fatigue cracking of JPCP, where cracking is a key measure of concrete pavement performance as the deterioration of a fully developed transverse crack often accelerates roughness through spalling and faulting.; Depending on the aggregate interlock properties, repeated truck traffic may result in shattered slabs that require replacement. A new simple aggregate interlock model is also proposed that incorporates the principal mechanisms of shear load transfer through aggregate interlock, namely the initial free slip and sliding during wheel (service) loading for different crack widths. The model captures the highly nonlinear shear behavior of JPCP cracks. The model was developed based on extensive laboratory testing of large-scale slabs on full-depth foundations, and model was optimized from laboratory measured slab deflection basins and excellent reproducibility was achieved between experimental and numerical predicted slab deflection basins. The model was calibrated from results of five concrete mixes described with different aggregate interlock properties. The model was verified with results from a duplicate slab and excellent predictions were attained. The proposed aggregate interlock model can be incorporated in numerical pavement analysis tools to predict the added tensile stresses in a JPCP slab due to the nonlinear aggregate interlock behavior.