Investigation on fundamental properties and chemical characterization of water-soluble epoxy resin modified cement grout

Abstract

In order to improve the defects of conventional cement-based grout such as low strength, brittle failure, weak bonding, and poor stability, water-soluble epoxy resin was designed and used to modify cement-based grout. The purpose of this study is to investigate the feasibility of water-soluble epoxy resin as a high-performance tunnel grouting modifier through the rheological and mechanical properties analysis and chemical characterization of composite grout with different epoxy content and water-cement ratio. The results demonstrated that the fluidity of epoxy resin modified composite grout increased first and then decreased with the addition of epoxy resin. The addition of epoxy resin effectively reduced the bleeding ratio, and kept the grouting fluidity for a certain period of time after mixing. The average particle size of composite grout decreased. Epoxy resin particles and cement particles had opposite zeta potential, and electrostatic attraction occurred in the suspension. The absolute value of zeta potential first increased and then decreased with the increase of epoxy resin. The uniaxial compressive strength and splitting tensile strength of composite grout were observably improved by the modification of epoxy resin, and the ultimate strain was also significantly increased under high epoxy content, and the brittle failure characteristics of the material were improved. With the increase of the content of epoxy resin, the yield of calcium hydroxide in the hydration products increased while the content of calcium carbonate decreased. Epoxy resin contributed to the hydration reaction of cement, while excessive epoxy resin formed a film structure inside to restrict further hydration. The modification of epoxy resin significantly improved the bonding ability of composite grout, and the epoxy resin was uniformly distributed inside the composite grout. The core of the chemical reaction in the modification process was the reaction between free calcium ions and –OH in epoxy resin, and a complex cross-linking network structure was formed with calcium ions as the node. Compared with neat cement paste, epoxy resin modified composite grout had obvious advantages in strength, ultimate strain, fluidity, stability, and bonding ability, so it had broad research potential and application prospect.