Abstract
The purpose of the present research is to investigate the sustainable performance of fly ash concrete at elevated temperature. Initially, the optimum level of cement replacement with class F fly ash was determined. The concrete mixes, i.e., plain concrete (0% fly ash), 25% fly ash, and optimum level of cement replacement with fly ash (i.e., 40%), were chosen to determine the residual compressive strength of concrete after a single heating-cooling cycle of elevated temperature ranging from ambient to 400 degrees Cat an interval of 200 degrees C under unstressed and stressed conditions. The microstructure by scanning electron microscopy (SEM) was also examined for all the concrete mixes. During the heating-cooling process, the hysteresis loop at 400 degrees C is found larger than the hysteresis loop at 200 degrees C and ambient temperature. The 40% fly ash concrete showed a lower reduction in the residual compressive strength after heating at 400 degrees C under the unstressed condition. The 40% fly ash concrete has shown maximum residual compressive strength than 25% fly ash and plain concrete after heating at 200 degrees C and 400 degrees C under the unstressed and stressed conditions. The SEM analysis indicates a massive change in the morphology at 400 degrees C for plain and fly ash concrete mixes.