Performance evaluation of fly ash and ground granulated blast furnace slag‐based geopolymer concrete: A comparative study

Abstract Nowadays, geopolymers, which are more environmentally friendly than cement due to the high energy requirements and high carbon dioxide (CO 2 ) emissions of cement production, emerge as alternative binders. In this study, the mechanical and durability properties of geopolymer concrete (GC) based on ground granulated blast furnace slag (GGBS) (100GGBS), 50% fly ash (FA) and 50% GGBS (50FA50GGBS), and FA (100FA) with two different water/geopolymer solids ratios (W/GP) of 0.33 and 0.35 were investigated. Slump, compressive strength, splitting tensile strength, unit weight, water absorption, elevated temperature resistance, abrasion resistance, modulus of elasticity, and drying shrinkage tests were carried out. As the percentage of FA in the mixture increased, the slump of the concrete increased, while the cohesion of the concrete decreased and the setting time was delayed. The addition of GGBS increased the compressive strength and the splitting tensile strength of the GC by up to 377% and 278%, respectively. Under the effect of elevated temperature, the 100FA concrete showed less strength loss and weight loss than other concrete. After the abrasion test, 100GGBS concrete lost about 2.5 times less weight than 100FA concrete. The drying shrinkage of geopolymer mortar reached a maximum of 100 microstrains. Among all concrete, 50FA50GGBS‐0.33 showed the highest performance in terms of overall performance.