Material characterization of high-ductility geopolymer composites developed with industrial and construction & demolition wastes

• Mechanical and microstructural behavior of high-ductility geopolymer composites. • Recycled cement paste enhances geopolymer strength by up to 14.7 %. • Full silica fume replacement with RCPP densifies microstructure effectively. • RCPP outperforms RACP in alkali reactivity and polymerization. • Partial RP replacement maintains strength; full RP lowers performance. The present study aims to assess the mechanical and microstructural performance of high-ductility geopolymer composites (GC) developed with industrial and construction & demolition wastes. The industrial waste included silica fume (SF) and metakaolin (MK) while the construction & demolition wastes included recycled aggregate concrete powder (RACP) and recycled cement paste powder (RCPP). Results showed that partial substitution of SF and MK with RACP or RCPP minimally affected strength, while full replacement reduced it significantly. Replacing SF entirely with RCPP improved strength by up to 14.7 %. SEM, XRD, and FTIR confirmed RCPP’s superior reactivity, denser microstructure, and enhanced polymerization compared to RACP.