SHRINKAGE AND THERMAL CRACKING OF FAST SETTING HYDRAULIC CEMENT CONCRETE PAVEMENTS IN PALMDALE, CALIFORNIA

This report describes the investigation of the transverse cracking of Jointed Plain Concrete Pavement (JPCP) test slabs in Palmdale California under environmental loading. The slabs were constructed using Fast Setting Hydraulic Cement Concrete (FSHCC) as part of the California Department of Transportation (Caltrans) accelerated pavement testing program (CAL/APT). Cores drilled through the cracking indicated that top-down cracking had occurred. Concrete shrinkage and thermal strain data from field instrumentation was recorded and analyzed to determine the cause of the cracking. Using the measured strains and temperatures, finite element analysis predicted high tensile stresses at the top of the test section slabs due to the differential drying shrinkage between the top and base of the slab, as well as the non-linear nature of the negative temperature gradients through the slab. Laboratory tests on the test section cement revealed significantly higher shrinkage than ordinary Type II Portland cement. Recommendations are presented.