Swell and Compressibility of Sand-Expansive Clay Mixtures

摘要

This paper investigates the swelling and compressibility characteristics of a sand-natural expansive clay mixture for use as a hydraulic barrier. Natural expansive clay used in this study was obtained from the city of Al-Qatif located along the Arabian Gulf coastal region, Saudi Arabia. For these mixtures, sand was considered the host material and clay content varied between 10% and 60% by dry weight of sand. A series of one-dimensional odometer tests was conducted to evaluate the swelling potential, swelling pressure, and compressibility characteristics of sand-clay mixtures at two initial molding conditions (optimum and wet-of-optimum conditions). Trends for the variation of swelling potential, swelling pressure, compression index and re-compression index with clay content were evaluated. These trends were consistent with fabric of sand-clay mixtures observed using scanning electron microscope technique. Furthermore, tests results revealed that the initial molding conditions and clay content had a significant effect on the swelling potential and compression index of sand-clay mixtures. For the sake of comparison, similar tests were performed on sand-bentonite mixtures with clay content ranging from 5% to 20%.