Advances in one-part geopolymer systems: fundamentals, manufacturing, and comparative insights with two-part geopolymers

Geopolymers have emerged as a promising and sustainable alternative to ordinary Portland cement (OPC), offering significant reductions in CO₂ emissions, enhanced mechanical performance, and improved durability while enabling the utilization of industrial and agricultural by-products. In recent years, growing demand for eco-efficient construction materials has led to the development of one-part geopolymers (OPtG), also known as “just add water” systems. Unlike conventional two-part (TPtG) formulations that rely on liquid alkaline activators, OPtG are synthesized by mixing solid precursors with solid activators and water, simplifying the production process and improving safety and practicality. The mechanical performance of OPtG is strongly influenced by the synergistic interaction between precursors and activators, which governs their hydration behavior, setting, and hardening mechanisms. Despite these advantages, several challenges remain, including the limited availability and environmental implications of current raw materials, as well as the need for efficient valorization of industrial wastes as suitable constituents. This review provides a comprehensive overview of the key factors influencing the properties of OPtG, including hydration process, flowability, setting time, compressive and flexural strength, shrinkage, and efflorescence. Furthermore, it compares the reaction mechanisms of OPtG and TPtG systems, highlighting the differences in their hydration stages and performance characteristics. The findings underscore the crucial role of activator chemistry and precursor compatibility in optimizing the mechanical and durability performance of one-part geopolymer binders for sustainable construction applications.