Residual mechanical properties of concrete containing lightweight expanded clay aggregate (LECA) after exposure to elevated temperatures

Abstract

AbstractThe mechanical properties of light‐weight concrete (LWC) in fire are known to be better than those of normal‐strength concrete (NSC), both at high temperature (hot properties) and after cooling (residual properties). The objective of this paper is to increase the knowledge of LWC's residual properties by testing a number of mixes containing expanded clay as light‐weight coarse aggregate. An experimental program was carried out, in which one normal‐weight concrete mix and two lightweight aggregate mixes containing different amounts of LECA were used to fabricate 72 concrete cylinders and 36 concrete prisms. All mixes contained silica fume as a supplementary cementitious material. The specimens were tested at the ambient temperature and after exposure to temperatures of 250, 500, and 750°C to obtain their compressive and tensile strength, modulus of elasticity, and stress–strain response. Results indicate that exposure to temperatures up to 250°C has no significant effect on the mechanical properties of concrete containing LECA just as in normal weight concrete. However, with increasing the temperature, increasing the lightweight aggregate content of the mix resulted in better strength retention after exposure to elevated temperatures. The experimental data are also used to develop equations to evaluate the residual mechanical properties of concrete.