Effects of LECA Content on the Behavior of Steel Fiber-Reinforced Geopolymer Concrete at High Temperature

Abstract This paper examines how steel fiber and the amount of lightweight expanded clay aggregate (LECA) affect the mechanical and microstructural properties of geopolymer concrete (GPC) made from fly ash after being heated. LECA has been used with different contents (0, 10, and 20%) as a partial replacement by weight of coarse aggregate. Steel fiber has been employed in GPC with volume fractions of 0 and 1%. A slump test was applied to examine the workability of fresh concrete. Compressive strength, splitting tensile strength, flexural strength, and elastic modulus tests also measured the mechanical properties. Furthermore, the microstructure characterization was also carried out by performing scanning electron microscopy (SEM). The findings suggest that including steel fiber and raising the LECA content in the mixture enhanced the strength’s retention following high-temperature exposure. After being exposed to a constant temperature of 800°C, GPC containing steel fiber and 20% LECA achieved the best result compared to the plain GPC in terms of decrease in mass, residual compressive and tensile strengths, residual flexural strength, and residual amount of elastic modulus: 6.04 and 4.39%; 27.08 and 39.27%; 37.6 and 47.02%; 16.07 and 30.3, and 2.17 and 6.19%, respectively.