Effect of pressure impregnated of methyl silicate (TMOS) on pore structure and impermeability of cement mortar

The pressure-impregnation crystallization reaction of methyl silicate (TMOS) was investigated. Taking TMOS as impregnating agent and water absorption and compressive strength as evaluation indexes, the effects of impregnating pressure, impregnating time, and TMOS concentration were studied. The results showed that the best results were obtained at an impregnation pressure of 1.0-1.2 MPa, impregnation time of 1.0 h, and TMOS concentration of 100%. The water absorption of the samples treated with pressure impregnation decreased by 55.25%, and the compressive strength increased by 17.77% compared with the samples treated with atmospheric impregnation. The average penetration depth increased from 1.2 mm to 6.0 mm after 1.0 h of impregnation. Moreover, TMOS reacted with Ca(OH)2 can produce fibrous C-S-H and more C-S-H gels during pressure impregnation, which reduces porosity and optimize pore structure. It was demonstrated that pressure impregnation helps TMOS penetrate deeper into the mortar and improve its impermeability.