关键词: 水泥基阻截墙; 硅灰; 渗透性能; XRD;

Abstract: In order to develop a plastic concrete cutoff wall system with better anti-seepage effect and mechanical properties, a series of slump, permeability, mechanical strength, elastic modulus and XRD tests were carried out to study the effect of silica fume on the permeability and mechanical properties of soil-cement-bentonite cutoff wall.The test results showed that with the gradual increasing of silica fume content, the permeability coefficient of the modified cutoff wall decreased first and then increased, and the compressive strength increased sharply first and then increased slowly.When the dry matter content was 5.1% silica fume, 76.55% clay, 8.35% bentonite and 10% cement, the modified cutoff wall can obtain lower permeability coefficient( 1.02×10-9 m/s),appropriate compressive strength( 0.951 MPa),and lower elastic modulus( 1 244.5 MPa).When the moisture content was 66.76%,it could meet the workability standard.The XRD analysis results showed that the hydrated calcium silicate was generated by the hydration products of silica fume and cement, which could effectively fill the pores of the wall and increase the density of rock and soil matrix.Silica fume has potential application value in improving the mechanical strength and reducing the permeability coefficient of concrete cutoff wall.At the same time, it realizes comprehensive utilization of solid waste.The modified cutoff wall is expected to be applied in the seepage prevention of water conservancy project foundation.

Key words: soil-cement-bentonite cutoff wall; silica fume; permeability; XRD;