High-volume basalt waste blended cements

Large volumes of basalt waste (BSW), by-products of basalt stone crushing, are generated in large amounts, resulting in serious environmental pollution and health hazards. BSW is classified as a pozzolanic material and is suitable for use in cement-based mixes, according to ASTM C618. Considering their high-specific surface areas and SiO2 and Al2O3 contents, BSW powders can be incorporated as supplementary cementitious materials (SCMs) in concrete and precursors in alkali-activated materials (AAMs). As SCM, BSW has been studied extensively in the laboratory in the range of 0%–30% replacement of cement by mass. However, increasing the BSW content decreases the compressive strength of the mixes, increasing in carbon intensity and cost intensity. Alternatively, BSW-based AAMs can result in reduced CO2 emissions, energy consumption, and cost when used in construction components. Depending on the activator used, the main reaction product in these mixes is C-S-H gel. This chapter reviews the inherent properties and usability of BSW in construction materials, including their: (1) characteristics (physical and chemical compositions), (2) activity estimation and quality assessment, (3) properties of BSW-blended cements at both fresh and hardened stages, (4) properties of BSW-based AAMs, and (5) environmental impact and cost evaluation.