Influence of matric suction on the long-term behavior of fouled road base materials under traffic loading

Abstract

The road base and subbase materials are normally in unsaturated condition, and fouled by fines due to subgrade pumping. These unsaturated fouled materials usually present different properties due to combined effects of matric suction and fine content. To study the long-term behaviors of these materials, a series of large-scale cyclic triaxial tests were conducted. Crushed tuff aggregates, incorporated with corresponding kaolin contents, were selected to be the testing materials. Cyclic loadings with two amplitudes were applied on the mixture specimens under four initial matric suctions and two fine contents. The matric suction was controlled by axis-translation method. The accumulated axial strain and resilient modulus were focally analyzed. The testing results show that for materials with higher fine content, the hysteresis phenomenon during the drying and wetting path of the soil-water characteristic curve will be more obvious. Under cyclic loadings, the resilient modulus increases with the increase of matric suction, and the increase rate decreases with the increase of matric suction. The accumulated axial strain decreases with the increase of the matric suction, and the decrease rate decreases with the increase of matric suction. Larger cyclic loading amplitude and higher fine content will amplify the influence of matric suction.