The influence of mixing polyurethane on the shrinkage and matric suction of local clay and its effectiveness as a compacted clay liner subjected to wet-dry cycles

• Main Author: Frianeza, Cielo D.
• Format: text
• Language: English
• Published: Animo Repository 2022
• Subjects: Clay—Permeability; Polyurethanes; Sanitary landfills; Civil Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etdm_civ/15
• Institution: De La Salle University

Sanitary landfill is a solid waste disposal site with control over the potential impact of solid waste on the environment and public health by preventing contamination using impermeable liners. Several studies have shown that a compacted clay liner deteriorates when exposed to wet-dry cycles due to its high shrinkage potential, which could affect its permeability. Hence, the study aimed to investigate the influence of mixing polyurethane, a stable and impermeable material, with local clay on the permeability at different stages of three wet-dry cycles along the drying path of the compacted mixture. Through experimentation, it was inferred that the hydraulic conductivity of compacted polyurethane-clay liner is acceptable based on the requirement of the design standard for all sanitary landfill categories. Moreover, compacted polyurethane-clay liner is more impermeable compared to compacted local clay in both saturated and unsaturated condition. The measure of permeability in an unsaturated state was predicted from the fitted water retention curve for a wide range of moisture content for three wet-dry cycles of compacted local clay and compacted polyurethane-clay liner. Furthermore, compacted polyurethane-clay liner is more resistant to shrinkage than compacted local clay whether compacted local clay had the same or less amount of voids. However, based on the qualitative analysis of the desiccation cracks, the specimen with polyurethane had a larger crack network than the local clay when observed visually. Thus, the changes in the soil structure induced by the polyurethane on the local clay had significant effects on the permeability and shrinkage characteristic as water evaporates from the compacted soil mass.