Study of Capillary Saturation Distribution of Unsaturated Dam Concrete in Low-Temperature Environment

During dam operation, saturation before freezing strongly affects the freeze-thaw deterioration of concrete in the downstream zone.However, previous experimental studies of capillary water absorption by concrete generally involve drying rich cementitious material specimens without considering gravity and low temperature.A capillary water absorption method for horizontal absorption and infiltration absorption is proposed by using high-pressure PE flat pocket design.Next, secondary aggregate grading dam-concrete specimens are prepared with three water-cement ratios, three low temperatures, and two curing ages to explore the saturation distribution of specimens at different depths with respect to the suction surface after 14 days of capillary water absorption.The test results show that, after 14 days of capillary water absorption by unsaturated dam concrete, the saturation decreases significantly with increasing depth and then stabilizes at a certain level.The relationship between saturation and water-binder ratio, ambient temperature, and age is θ_0.41<θ_0.50<θ_0.60, θ_2℃>θ_8℃>θ_5℃, and θ_28d>θ_90d.The saturation measured by the infiltration absorption method exceeds that measured by the horizontal absorption method, but the water diffusion depth measured by the infiltration absorption method and the horizontal absorption method does not exceed 17.5cm.