Experimental Study on Performance of Modified Cement-Based Building Materials under High-Water-Pressure Surrounding Rock Environment

Abstract

Traditional cement-based grouting materials have good reinforcement and anti-seepage effects on the surrounding rock under normal conditions, but the grouting effect is not ideal due to problems such as a long setting time, a low stone ratio, and poor crack resistance under high water pressure and in a dynamic water environment. In this study, we aimed to improve the physical properties, chemical properties, and microstructure of a cement-based slurry by forming a hydrogel through its chemical crosslinking with polyvinyl alcohol and boric acid as modifiers for the purpose of improving the permeability resistance of the surrounding rock grouting under high-water-pressure conditions, which can expand the function of traditional building materials. The grouting effect of the modified cementitious material on the surrounding rock was analyzed through indoor tests, the SEM testing of the performance of the modified slurry, the numerical calculation of the seepage field, and the application of the modified slurry in combination with the actual project to verify the water-plugging effect. The research findings demonstrate that (1) the additives boric acid and PVA can significantly speed up the slurry gel time, and the gel time can be controlled within 2–20 min to meet the specification requirements. (2) At a velocity of moving water > 1 m/s, the retention of the solidified modified slurry stone body reaches more than 80%. According to the SEM analysis, the structure of the solidified modified slurry stone body is dense and has good impermeability. (3) According to the numerical calculation analysis, the modified slurry can effectively change the seepage field of the surrounding rock and improve its seepage resistance. The water pressure outside the lining is reduced by 47%, 31%, and 22%, respectively, compared with no slurry, the pure cement slurry, and cement–water-glass grouting, and the indoor test and numerical simulation conclusions are consistent.