Sustainable utilization of basalt waste dust as replacement of river sand in one‐part geopolymer mortar

Abstract With growing environmental concerns due to the excessive use of natural river sand in construction, finding sustainable alternatives is crucial. This study explores the potential of basalt waste dust, a by‐product of basalt rock crushing, as a replacement for river sand in one‐part geopolymer mortar. The experimental program is segmented into three series: replacing river sand with basalt waste dust at 25%, 50%, 75%, and 100%; adjusting the activator‐to‐binder ratio as 0.12, 0.15, 0.18, and 0.21; and modifying the aggregate‐to‐binder ratios (1, 1.4, 1.8, and 2.2). Results are discussed using various test results such as fresh property, hardened property, and microstructural property to provide a detailed analysis of mixture properties. Findings in series 1 reveal that replacing 50% of river sand with basalt waste dust optimally enhances the fresh and hardened properties of geopolymer mortar. In series 2, the varying activator‐to‐binder ratio with optimum replacement from series 1, activator‐to‐binder ratio 0.15, was found to be optimal, improving hardened properties. Further opting for this ratio in series 3 and increasing the aggregate‐to‐binder ratio to 2.2 was found to positively impact both the hardened and microstructural properties of one‐part geopolymer mortar. This study demonstrated that basalt waste dust plays a crucial role in these improvements and emphasizes the necessity of optimizing mix proportions to achieve superior performance, establishing basalt waste dust as a viable and sustainable alternative to river sand.