Lateral Shrinkage of Compacted Polyurethane-Clay Subjected to a Single Wet-Dry Cycle

Abstract

Compacted clay is often used as a sanitary landfill liner due to its impermeable characteristics. However, compacted clay is susceptible to shrinkage as the temperature changes, which may affect the permeability due to the development of shrinkage cracks. Thus, clay was mixed with polyurethane, a stable polymer, once the reaction was completed. The polyurethane-clay mixture was compacted wet of the optimum moisture content and monitored through several moisture contents using direct measurement of the specimen diameter by Vernier caliper. The study inferred that the ratio of the lateral shrinkage of the compacted polyurethane-clay mixture is significantly less than that of the clay specimen with the same initial void ratio. Hence, the changes in the soil structure induced by the addition of polyurethane into the compacted mixture increased the resistance of the soil mass from lateral shrinkage quantified using the free shrinkage ratio. Furthermore, the regression model of the free shrinkage ratio for a wide variety of moisture content was also presented for the compacted polyurethane clay and compacted clay.