Effect of processed pozzolans on residual mechanical properties and macrostructure of high-strength concrete at elevated temperatures

Recently, use of processed pozzolans such as rice husk ash (RHA) and bagasse ash (BA) have been identified as promising mineral admixtures to produce HSC. As fire is considered one of the severe hazards to which a structure may be exposed, there is a requirement to evaluate the performance of HSC containing pozzolanic admixtures, namely, RHA and BA at elevated temperatures. In this study, the residual mechanical properties comprising, compressive and splitting tensile strength, compressive stress-strain response, and static elastic modulus of HSC mixtures made with 10% RHA, 10% BA as cement replacement are presented. The properties were investigated at different temperatures up to 800 degrees C, at a slow heating rate of 3 degrees C/min. Results reveal that the residual mechanical properties of pozzolanic concretes deteriorate at elevated temperatures with significant loss above 200 degrees C. Visual observations of the physical deterioration reveal that the cracking in specimens mostly initiates during the cooling phase and develops extensively in all concrete types at exposure temperature of above 400 degrees C.