Durability and microstructure of ternary binder geopolymer concrete: A comprehensive study

Geopolymer concrete (GPC) is emerging as a promising, eco-friendly alternative to traditional cement concrete due to its lower carbon footprint and enhanced durability. A key challenge with geopolymer concrete is its dependence on heat activation at varying temperatures, which restricts its practical applications. In this study, the impact of various molarities of NaOH (2 to 10 M) on the sorptivity, sulfate attack resistance, and microstructure of geopolymer concrete (GPC) made with ternary binders is investigated. Ternary binders of Fly Ash, GGBS, and Nano silica are utilized in the proportion of 49:48:3 for all the molarities. Concurrently, Plain Cement Concrete (PCC) of equivalent grade is assessed for comparative analysis. The study found that GPC with a 10 molar concentration exhibits less weight loss and strength degradation, at 1.24% and 12.26%, respectively, when immersed in a sulfate solution. The sorptivity test reveals that GPC with 10M had the lowest water absorption, measuring only 0.14mm compared to the other mixes. The formation of (N-A-S-H) was observed in all samples, indicating a compact and dense microstructure of the geopolymer matrix. This study finds an alternate binder to traditional cement concrete with lower molar concentration, that can exhibit better performance in durability characters.