Experimental investigation on performance of concrete with zeolite, silica fume and fly ash after exposure to elevated temperatures

Purpose This study investigated the impact of substituting zeolite and industrial by-products, silica fume and Class C fly ash, for a portion of cement on the performance of high-strength concrete for M50 and M60 concrete grades at room and elevated temperatures. Design/methodology/approach The optimum mix is initially determined by varying zeolite replacement from 10% to 30%, silica fume at 7.5%, and Class C fly ash, which constitutes 10% by weight of cement. The mechanical properties of concrete, including compressive strength, split tensile strength and flexural strength, are determined, and the optimum mix for adding zeolite is identified. Further, concrete specimens with optimum and conventional mixes are tested for mechanical properties after exposure to elevated temperatures of 200°C, 400°C and 600°C. Reinforced concrete beams cast with conventional and optimized mixes are examined for flexural behaviour at room temperature and an elevated temperature of 600°C. Findings The optimum mix for the addition of zeolite is identified as 10%, with silica fume and class C fly ash used for cement replacement. Exposure to elevated temperatures resulted in the retention of mechanical properties at higher percentages for the optimized mix in comparison with the conventional concrete mix. A higher value of load-carrying capacity is retained for heated beams with the optimized mix. Originality/value This study specifically examines the residual strength of high-strength concrete incorporating zeolite, silica fume and class C fly ash after exposure to elevated temperatures.