A review of residual strength properties of normal and high strength concrete exposed to elevated temperatures: Impact of materials modification on behaviour of concrete composite

This study presents a review of residual strength properties of normal and high strength concrete exposed elevated temperatures: the implication of natural and recycled aggregates, the addition of mineral admixtures, and fibre. The influence of supplementary cementing materials such as fly ash, blast furnace slag, silica fume, metakaolin, and commonly used fibers: steel and polypropylene on concrete residual compressive and tensile strength, modulus of elasticity, and stress–strain behaviour after exposure to elevated temperature were considered. The data obtained from previous laboratory test results are compiled to understand the role played by room temperature compressive strength and varying concrete mix material composition on residual mechanical properties of concrete. A statistical analysis of normalized residual mechanical strength (the ratio of the original strength at room temperature to that obtained after the exposure to temperature) was carried out to rank and determine the significance each factor on the residual mechanical properties of concrete. The study showed that properties of concrete such as compressive strength, tensile strength, and stress–strain behavior with three testing methods: preloaded and tested hot, unloaded and tested hot, and unloaded and tested at room temperature (unstressed residual) have been explored by researchers. This study reported the unstressed residual testing method so as to allow uniformity and a common baseline for comparison. This review has shown lacking areas where there is need for extensive research regarding the residual strength properties of concrete subjected to elevated temperatures, especially concrete containing admixtures and fibers. The outcome of this review will be beneficial to researchers, engineers and constructors in the field of civil engineering and construction domain.