Global Research Trends in Biomass-Derived Geopolymers: a Bibliometric and Critical Review

Biomass-derived geopolymers have attracted increasing attention as sustainable alternatives to ordinary Portland cement (OPC), valorizing agricultural, forestry, and industrial residues into low-carbon binders. A bibliometric analysis based on the Scopus database indicates a marked increase in research activity after 2018, with publication output peaking in 2023. China, India, Australia, and several European countries emerged as the leading contributors to this research field. Keyword mapping revealed four dominant research themes: strength and durability, biomass valorization, environmental remediation, and advanced applications such as 3D printing and composites. A critical review of representative studies showed that agricultural ashes, including rice husk ash (RHA) and sugarcane bagasse ash (SCBA), have demonstrated compressive strengths ranging from 30 to 72 MPa under different mix designs and curing conditions. Forestry residues, particularly wood fly ash and lignin, improved sulfate resistance and achieved adhesive bonding strengths of up to 3.8 MPa, while industrial biomass wastes, including olive stone bottom ash (OSBA) and paper sludge, reported compressive strengths of 18–43 MPa and phosphate removal efficiencies of up to 98