Response surface optimization of coal-based geopolymer grouts for enhanced anti-dispersion performance

Research on anti-dispersion grouting materials helps improve the retention and durability of grout under water-bearing or flowing-water conditions, reduce material consumption and environmental risks, and provide technical and theoretical support for the reliability and sustainability of ground reinforcement projects. This research utilized coal gangue (CG), fly ash (FA), and silica fume (SF) as raw materials rich in silicon and aluminum. Alkali activators with varying concentrations were prepared by mixing sodium silicate solution with NaOH, and a small quantity of admixture was added to develop a cost-effective anti-dispersion grouting material (AGM). The macro tests evaluating fluidity, setting time, water-to-land strength ratio under static water conditions, and retention rate under flowing water conditions of AGM were designed using the response surface method. The reaction mechanism of AGM was investigated XRD, FTIR, SEM-EDS, and NMR techniques. The results indicate that when the content of hydroxyethyl methyl cellulose (HEMC) is 0.5 %, the modulus of water glass is 1.53M, and the concentration of alkali activator is 0.45, the optimal formula can be achieved. This material exhibits excellent flowability during construction, ensuring smooth grouting operations. It also demonstrates outstanding resistance to water scouring, forming a high-strength underwater consolidation body in static water environments.