Abstract: Objective: To investigate the influence of phosphoric acid mass fraction on the properties of sodium silicate grouting materials, with the goal of reducing sandy layer permeability and consolidating surrounding soil, the research is specifically carried out. Method: Through laboratory tests, the properties of sodium silicate slurry with different phosphoric acid concentrations are measured. A set of integrated experimental platforms for permeability coefficient measurement and simulated grouting are developed to explore the effects of different grouting material ratios on the improvement of sandy layer antipermeability performance. Result & Conclusion: When the pH value of the grouting material is between 3 and 5, the setting time can be controlled within 30 seconds to 70 minutes, which is easier to control than alkaline slurry, making it advantageous for engineering applications. As the phosphoric acid content increases, the gel shrinkage of the grouting material becomes slower in acidic conditions and faster in alkaline conditions. Moreover, when the grouting material is acidic, the decay time of the antipermeability performance of the consolidated sand body advances as the slurry pH decreases and stabilizes after 12 days. In contrast, when the grouting material is alkaline, the antipermeability performance of the consolidated sand body remains relatively stable for 1 to 3 days, with a decline in performance occurring after 3 days. Additionally, this decline becomes more rapid with decreasing pH values of the grouting material.