One-part alkali-activated materials: A review

Alkali-activated materials (AAM) are recognized as potential alternatives to ordinary Portland cement (OPC) in order to limit CO₂ emissions as well as beneficiate several wastes into useful products. However, the alkali activation process involves concentrated aqueous alkali solutions, which are corrosive, viscous, and, as such, difficult to handle and not user friendly. Consequently, the development of so-called one-part or “just add water” AAM may have greater potential than the conventional two-part AAM, especially in cast-in-situ applications. One-part AAM involves a dry mix that consists of a solid aluminosilicate precursor, a solid alkali source, and possible admixtures to which water is added, similar to the preparation of OPC. The dry mix can be prepared at elevated temperatures to facilitate the reactivity of certain raw materials. This review discusses current studies of one-part AAMs in terms of raw materials, activators, additives, mechanical and physical properties, curing mechanisms, hydration products, and environmental impacts.