Basalt powder as a sustainable precursor in alkali‑activated materials: a critical review of performance, mechanisms, and durability

Abstract The environmental burden of Portland cement (PC) production has intensified interest in low-carbon binder alternatives, among which alkali-activated materials (AAMs) have gained significant attention due to their reduced clinker demand and enhanced durability. However, the large-scale deployment of AAMs is constrained by the limited availability and variability of conventional industrial by-product precursors such as slag and fly ash. Basalt powder (BP), an abundant natural material often generated as quarry fines, has recently emerged as a supplementary or partial precursor in alkali-activated slag, fly ash-based, metakaolin-based, and other geopolymer systems. This review critically examines the effects of BP incorporation on fresh properties, mechanical performance, shrinkage, transport behavior, durability, and microstructural evolution. The findings indicate that BP exhibits a dual role: acting primarily as a micro-filler that refines pore structure and enhances matrix densification, and secondarily as a low to moderately reactive source of Si, Al, and Ca contributing to the formation of hybrid binding gels. Moderate BP replacement levels (≈ 20–30%) generally improve strength, dimensional stability, and durability, while excessive substitution may dilute reactive phases and hinder binder development. The environmental implications of BP utilization and its potential for valorizing quarry by-products are also discussed, highlighting BP as a promising component for developing robust and sustainable alkali-activated binders.