Preparation and reinforcement performance of composite sodium silicate-based grouting materials for glacial till

• Sodium silicate-based grout modified with EGDA and sodium tetraborate decahydrate: • With increasing EGDA content, the gel time decreased from 11,940 seconds to 330 seconds. • Sodium tetraborate decahydrate significantly improved gel stability. • Increasing the grout dosage improved compressive strength (UCS) and durability. • Both field and laboratory tests confirmed the effective penetration of the grout. To address the difficulty of grouting reinforcement in high-pressure, densely compacted soil strata, this study developed a sodium silicate-based grouting material with ethylene glycol diacetate (EGDA) and sodium tetraborate decahydrate (Na₂B₄O₇·10H₂O). The effects of the Baumé degree of sodium silicate, EGDA dosage, and sodium tetraborate decahydrate content on gelation behavior, grout injectability, and the mechanical properties of the consolidated body were systematically evaluated. Results indicated that EGDA markedly reduced the gelation time of the grout. Increasing the EGDA content from 1% to 6% shortens the gelation time from 11940s to 330s. Increasing the sodium tetraborate decahydrate content from 0% to 2% decreased the 72-hour water release rate from 20.2% to 2% and reduced volumetric shrinkage by 93%, significantly enhancing the gel’s stability. At a grouting concentration of 24% in glacial till, the 28-day compressive strength increased to 2.23 MPa, which is 5.6 times higher than that of the single sodium silicate grouted soil, and the softening coefficient improved by 20.7%. Microscopic analysis revealed that hydrated silica gel was the primary reaction product. The three-dimensional network structure in the gel cemented the glacial till particles into a single entity, thereby improving the performance of the consolidated structure. The method was validated through an indoor grouting simulation device and applied in a grouting reinforcement project for high-pressure dense formations in the plateau region.