Advances in Research

Ordinary Portland cement (OPC) production generates substantial carbon emissions and imposes considerable ecological burdens, thereby driving global research on low-carbon alternative cementitious binders. Geopolymers, formed through the alkali activation of aluminosilicate industrial solid wastes, have emerged as promising sustainable materials for replacing OPC. This narrative review integrates the research framework of geopolymer materials, covering core definitions, classification systems, four-stage geopolymerisation and polycondensation mechanisms, and microscopic characterisation techniques. Representative precursor systems, including metakaolin, fly ash, blast furnace slag and multi-solid waste composites, and three major categories of alkali activators are summarised, with attention to the regulation of workability, mechanical strength, volume stability, multi-scale durability, high-temperature resistance and heavy metal immobilisation capacity. A comparative table distinguishes the strengths and limitations of four typical geopolymer precursor systems. This paper also discusses six major industrial application scenarios, including green prefabricated components, refractory and anti-corrosion materials, hazardous waste stabilisation, geotechnical solidification, 3D printing feedstock and multifunctional intelligent geopolymer composites. Key bottlenecks restricting large-scale industrialisation are identified, including unstable raw material composition, corrosive liquid activators, excessive drying shrinkage, insufficient long-term field service data and the absence of unified international testing standards. Targeted future research directions are proposed, including low-corrosion single-component solid activators, multi-waste synergistic blending, fibre/nano toughening, functional integrated geopolymers, full life-cycle environmental assessment and global standard development.