Biomass-Integrated Alkali-Activated Binders for Sustainable Construction: A Systematic Review of Performance, Carbon Reduction, and Adoption Challenges

Ordinary Portland Cement (OPC) production is a major source of global CO 2 emissions, driving growing interest in sustainable binder alternatives. This systematic review examines biomass-integrated geopolymer and alkali-activated binder (AAB) systems as low-carbon construction materials, drawing on peer-reviewed literature and expert validation interviews. This study, conducted in accordance with the PRISMA 2020 guidelines and expert validation interviews, examines biomass-integrated geopolymer and alkali-activated binder (AAB) systems as low-carbon construction materials through the systematic screening and analysis of peer-reviewed literature (37 eligible studies identified from an initial pool of 195 records) and expert validation interviews. The review focused on well-studied biomass residues such as rice husk ash (RHA), sugarcane bagasse ash (SCBA), and biochar, which can contribute reactive silica and alumina and thereby influence geopolymerisation and pozzolanic reactions. The reviewed studies indicate that optimal biomass incorporation, typically at replacement levels of 20 to 30%, can achieve compressive strengths comparable to or higher than conventional systems while also improving durability through pore refinement, reduced permeability, and denser reaction products, including C-S-H and N-A-S-H gels. The reviewed studies collectively indicate carbon footprint reductions of 40 to 60% relative to OPC under efficient processing and localised supply conditions, synthesised across multiple life-cycle assessment studies in the dataset, primarily through reduced reliance on clinker and the valorisation of agricultural waste, with additional relevance to circular economy and waste-to-value strategies. Synthesised economic findings from the reviewed literature further suggest material cost reductions of 15 to 35% under localised production models. However, widespread implementation remains constrained by feedstock variability, processing energy demand, supply chain reliability, and limited regulatory standardisation. The 37-study systematic review indicates that biomass-integrated AAB systems offer compressive strengths comparable to conventional materials, with substantial carbon footprint and cost reductions. Expert interviews corroborated these findings while highlighting feedstock inconsistency, regulatory gaps, and supply chain limitations as key barriers. Both evidence streams conclude that standardisation and scale-up research remain essential for broader adoption.