Polymer Enhanced Clay-Sand Mixture

Using polymers to modify the properties of soils is an area of interest for designing landfills. Landfill closures requires conditions of long-term mechanical and hydraulic stability. This work studies the micro and macroscopic interaction of a fine soil (CRclay), a uniform sand (Sand) and an anionic polyacrylamide (APAM). APAM is a superabsorbent polymer that swells by two orders of magnitude when immersed in water. This paper emphasizes on understanding the interaction between different mixtures of APAM, Clay and Sand analyzing the physical properties, soil-water retention, microstructure by means of Mercury Intrusion Porosimetry (MIP), and volumetric and mechanical behaviour. Results shows an increase on swelling potential and swelling pressure for different Sand-CRclay-APAM mixtures. APAM reduce the microporosity and increase the water retention capacity of the mixtures. For the mechanical behavior, mixtures with APAM present higher unconfined compressive strength and more ductile behavior than mixtures without it (Sand-CRclay). The low hydraulic conductivity of the mixtures with APAM make it viable for its use as part of landfill cover installations.