Short-term mechanical performance and flexural behavior of reinforced slag-fly ash-based geopolymer concrete beams in comparison to OPC-based concrete beams

Abstract

The study presents experimental investigation on short term mechanical properties and flexural behaviour of conventional Ordinary Portland Cement (OPC) based concrete and slag-fly ash based geopolymer concrete. Conventional and geopolymer concrete mixes were designed to achieve compressive strength equivalent to M40 and M70 grade as per Indian standard code. Mechanical properties of concrete mixes such as compressive strength, split tensile strength, flexural strength, modulus of elasticity and Poisson's ratio were evaluated and compared. The flexural behaviour of reinforced concrete beams for both conventional and geopolymer concrete has been studied using 4-point bend test. The findings suggest that geopolymer concrete shows comparable mechanical properties in terms of split tensile strength, flexural strength and Poisson's ratio. However, modulus of elasticity of geopolymer concrete is lower than the conventional concrete of equivalent strength. Studies on flexure behaviour of reinforced concrete beams shows that both geopolymer and conventional concrete exhibit comparable flexural behavior in terms of load-deflection curves, yield load and yield moment. The amount of energy dissipated in flexure is marginally higher for high strength conventional concrete. Based on the visible cracks developed in flexure, it was concluded that the reinforced conventional concrete and reinforced geopolymer concrete show similar number and type of cracks in flexure.