Mechanical properties and stress-strain relationship of slag-based one-part geopolymer concrete: A comparative study

A comprehensive understanding of the engineering characteristics of one-part slag-based geopolymer concrete (SBGC) is instrumental in promoting its widespread adoption and optimized design, improving construction practices, and advancing sustainability in the built environment. This study examined the workability, development of compressive strength, tensile strength, modulus of elasticity, and stress-strain behavior of one-part SBGC. The long-term compressive strength of SBGC, under both ambient curing and water curing conditions, has also been examined. Multiple combinations of mixtures were assessed, accounting for diverse factors such as activator ratio, aggregate size, water-to-binder ratio, curing conditions and activator types. This research also proposes new equations for predicting tensile strength and modulus of elasticity for one-part SBGC. The findings reveal that water-cured specimens demonstrate up to 43 % higher compressive strength and 52 % higher tensile strength compared to those cured under ambient conditions. Increasing the activator proportion in the mixture notably accelerates the early-stage development of compressive strength and SBGC's modulus of elasticity. Furthermore, one-part SBGC exhibits a long-term strength development that surpasses conventional concrete by over 20 %. In addition, the stress-strain behavior of SBGC reveals its inherent fragility, marked by near-perfect linear elasticity that abruptly transitions to complete and sudden collapse, distinguishing it from ordinary concrete. Microstructural analyses indicate that elevating the activator ratio reduces the presence of unreacted GGBFS particles and quartz in the mixture, thereby promoting the formation of gel.