Investigation into the sustainable solid waste-based grouting materials with enhanced injectability, fluidity and strength

Grouting has become an essential technique to address structural stability in engineering projects within rock masses. This study aims to develop a set of sustainable solid waste-based grouting materials to improve their performance in terms of injectability, fluidity as well as early and long-term strength in jointed rock reinforcement applications. A set of experiments was designed using response surface methodology (RSM) in which the ultrafine cement was the base material. The impacts of adding microsilica, mineral powder and fly ash individually along with their interactive effects were systematically investigated through analysis of variance (ANOVA) focusing on slurry viscosity, consistency, setting time, fluidity and compressive strength. Experimental results revealed significant performance improvement in grouting materials with appropriate proportions of microsilica, mineral powder and fly ash. The optimized slurry with a composition of 6.0 % microsilica, 3.7 % mineral powder and 2.0 % fly ash demonstrated about 125 % and 38 % increase in its uniaxial compressive strength over 1 and 28 days, respectively, where there was a 34.7 % reduction in slurry viscosity. Scanning electron microscopy and energy-dispersive spectroscopy analyses illustrated a denser and more uniform microstructure in the optimized slurry. As a result, a promising approach was developed to re-utilize the waste resources for production of efficient grouting materials leading to a significant improvement in the environmental sustainability of rock engineering projects.