Study on single-direction water-blocking of waterproof membrane in silt subgrade

This paper proposes a new concept of single-direction water-blocking for waterproof membranes in silt subgrades to meet the demands of inhibiting capillary rising and allowing subgrade water downward through the waterproof membrane. Furthermore, a new approach to determine the total pore area in water-repellent soil is proposed using a contact angle test. The relationship between the water repellence of the waterproof membrane and the consumption of Sodium Methyl Silicate per unit Area (SMSA) is obtained for different levels of compactness. When SMSA consumption is less than 4 g/m2, the water repellence of the waterproof membrane is extremely poor, whereas, in the range of 4–10 g/m2, its water repellence is greatly enhanced. When the SMSA consumption is more than 10 g/m2, the water repellence becomes stable. The total pore area of the waterproof membrane decreases when the SMSA consumption is increased.