Performance of sustainable cement mortar and concrete containing recycled asphalt pavement (RAP) under tropical temperature

The mechanical properties of cement mortar and concrete containing recycled asphalt pavement (RAP) are sensitive to temperature due to the thermo-viscoelastic behavior of the bituminous binder. This research article investigated the effect of high ambient temperature on the performance of cement mortar and concrete containing RAP for sustainable pavement applications in tropical regions. The mortar and concrete containing RAP were prepared under RAP replacements of 0%, 25%, 50%, 75%, and 100%. After 28 days of curing, high ambient temperatures (i.e., 25°C, 35°C, 45°C, 60°C, and 75°C) were applied to the sample. Then, the ultrasonic pulse velocity (UPV) test was performed before conducting the compression test. The fractured specimen obtained from a compression test was employed to ascertain any changes in the microstructural components subsequent to exposure to high ambient temperatures through X-ray diffraction (XRD) analysis. The results indicated that the strength reduction was more significant for the cement mortar and concrete with higher RAP replacement as a result of high ambient temperature. The increase in voids brought on by moisture evaporation was the primary cause of the decline in cement mortar and concrete strength. The UPV and XRD analyses of the samples showed that another factor affecting the strength reduction of samples with RAP replacement was the change in the thermo-viscoelastic properties of the bituminous binder due to temperature. Cement mortar and concrete with RAP over 50% are not recommended for structural members due to high temperature sensitivity. The normalized relationship between compressive strength and temperature exposure was proposed for cement mortar and concrete containing RAP exposed to high ambient temperatures, with a high correlation coefficient. The parameter k t , which represents the effect of thermo-viscoelastic properties of bituminous binder on the strength reduction, was proposed as the key design parameter for cement mortar and concrete use in structural and non-structural road components exposed to tropical temperatures.