One-part geopolymers for sustainable structural applications: materials, performance, and future directions

One-part geopolymer (OPG), also known as “just-add-water” geopolymer, has attracted growing interest as a low-carbon and sustainable alternative to ordinary Portland cement (OPC) in the construction sector. Unlike conventional two-part geopolymers that require handling alkaline solutions, OPGs employ pre-blended solid activators with precursors, which greatly improves their suitability for cast-in-situ applications. This review summarizes recent progress toward reliable structural applications of OPG and fiber-reinforced OPG composites, with emphasis on mechanical performance at both material and structural levels. A total of 109 studies on OPG and 42 studies on OPG composites focusing on mechanical properties were systematically collected and analyzed. The effects of precursor chemistry, activator type and dosage, water content, aggregates, chemical admixtures, and curing conditions on the mechanical performance of OPG are critically reviewed. For OPG composites, the reinforcement mechanisms of steel, synthetic, natural/inorganic, and hybrid fibers are discussed, together with emerging findings on dynamic behavior under impact and blast loading. Available studies on structural members, as well as the sustainability and economic efficiency of OPG systems, are also summarized. The review identifies key knowledge gaps that currently limit codification and engineering implementation and proposes future directions for advancing OPG from laboratory materials to structural applications.