Insights into the effects of ceramic waste powder as a precursor and alkali-activators on engineering performance of high ductility engineered geopolymer composites

Utilizing ceramic waste powder as an alternative precursor to replace ground granulated blast-furnace slag and fly ash in high ductility engineered geopolymeric composites (EGC) holds significant promise for enhancing its sustainability. This study investigated the impacts of ceramic powder incorporation and alkali-activators parameters on the engineering properties of EGC. Replacement of slag with ceramic powder at levels below 25% exerted minimal adverse effects or even slight beneficial effects on the microstructure and mechanical properties, whereas complete replacement of slag resulted in a marked deterioration. Replacing 25–50% of fly ash with ceramic powder improved matrix microstructure and enhanced the mechanical performance of EGC, with excellent micro–macro properties retained even at 100% fly ash replacement. Co-substitution of slag and fly ash by ceramic powder enabled the production of high ductility EGC. Raising silica modulus and alkali content of alkali-activator promoted the formation of a dense gel network, and accelerated the dissolution and polycondensation of ceramic powder, thereby refining the microstructure and improving micro-macro mechanical properties. The tensile stresses of EGC-Ref, CWP-M1.1N7, CWP-M1.3N7 and CWP-M1.3N9 were 9.50, 10.47, 11.73 and 12.70 MPa; and their tensile strain capacities were 5.67%, 5.53%, 6.50% and 7.70%. High strength and high ductility EGC tailored to diverse engineering properties can be successfully developed through optimization of the ceramic powder replacement ratio, alkali-activator modulus, and alkali content.