Sustainable all-solid-waste ternary geopolymer grouting materials: Mechanical performance and microstructural evolution

To address the carbon emissions of cement-based grouting materials and the environmental challenges caused by industrial solid waste, this study developed a ternary all-solid-waste geopolymer grouting material incorporating ferronickel slag (FNS), blast furnace slag (BFS), and fly ash (FA). The properties of the geopolymer were systematically investigated under different mix proportions. The mixture containing 20wt% FNS, 50wt% BFS, and 30wt% FA achieved a 28-day compressive strength of 69.6 MPa, demonstrating excellent hardening performance. Increasing the BFS content or decreasing the FNS proportion enhanced flowability and shortened setting time. Microscopic analyses revealed that BFS promoted the conversion of N-A-S-H gel into C-A-S-H gel, which was responsible for the significant strength enhancement. Grouting simulation confirmed the effective penetration and consolidation capacity of the developed geopolymer in medium sand. These findings highlight the feasibility of utilizing industrial solid wastes for high-performance grouting applications, offering a sustainable pathway for large-scale solid waste valorization. • Developed 100% solid-waste geopolymer using FNS, BFS, and FA via alkali activation • Achieved 69.6 MPa compressive strength and excellent flowability at optimal mix • BFS accelerated C-A-S-H gel formation, enhancing strength and microstructure • Moderate FNS addition improved compactness and interfacial bonding of the matrix • Grouting simulation confirmed strong consolidation (UCS = 9.36 MPa in 14 days)