Preparation and properties of anti-washout, high-temperature-resistant cementitious grouting materials

High-temperature water inrush was an inevitable challenge encountered during deep engineering construction, posing significant risks to both personnel and property. To improve the efficiency of high-temperature water inrush sealing, a novel anti-washout, high-temperature-resistant grouting material was developed using sodium silicate and three types of organic additives. This study employed the simplex-centroid design method to investigate the effects of polyacrylamide (PAM), hydroxyethyl methyl cellulose (HEMC), and carboxymethyl cellulose (CMC) on the washout resistance, viscosity, and early strength of the grout. The optimal mix proportion was determined using the efficiency coefficient method. Additionally, the mechanisms of the organic additives were explored through microscopic analysis. The results indicated that PAM enhanced the retention rate, viscosity, and early strength of the grout. HEMC significantly improved viscosity and strength but reduced the anti-washout properties. CMC increased the retention rate, but its inclusion resulted in a decrease in both strength and viscosity. The optimal mix proportion was found to be 1.5% PAM, 1% HEMC, and 1.5% CMC. Furthermore, the organic additives demonstrated a dual effect of flocculation and retardation. The active groups of the additives interacted with Ca2+, forming flocculation structures that improved washout resistance. Simultaneously, competition for Ca2+ with sodium silicate slowed the reaction rate, allowing the grout to remain in the fluid–solid phase for a longer period, which enhanced both its anti-washout properties and pumpability. Finally, the time-dependent viscosity of the new grout at varying temperatures was examined, and a rheological constitutive model was developed to describe the fluid–solid transition process.