Alternative Ground Improvement Solution with Polyurethane Foam/Resin

Abstract

Polyurethane (PU) foam/resin consists of two categories namely, hydrophobic PU and Hydrophilic PU. Hydrophobic PU is water resistant whereby the liquid form reacts and expels water from the voids in the soil. Hydrophilic PU reacts with the presence of water to form a gel and hardens to form flexible PU. The use of PU foam/resin has been explored in Europe, Korea, and Japan since the soil condition is likely to expand as water seeps into the voids and creates fissures and fractures within the soil body. The PU foam/resin is injected into the voids to fill in the gaps and creates bonding effect to the soil particles, enhancing the strength and reducing the permeability significantly. In Malaysia, the behavior of partially saturated soil is complex where the presence of suction in the microstructure influences the shear strength behavior of the soil. However, when the soil becomes fully saturated, where the suction drops to zero, collapse settlement occurs, which cause voids to increase within the soil body. Grouting methods either compaction, hydro fracturing, permeation, or compensation are used to inject the PU foam/resin into weak subsoil, hence increase the engineering characteristics of the soil. The objective of this implementation is (i) to increase the bearing resistance of the soil without increasing the weight or overburden of the soil; (ii) to shorten the time of implementation and eliminate the excavation process. Based on the results, the engineering characteristics of the soil have improved and the bearing resistance has increased to the desired values. The in situ tests conducted also show that the PU foam/resin becomes impenetrable and the strength of the soil has improved significantly. This paper presents the cases where hydrophobic PU foam/resin was injected to enhance the engineering characteristics of different soil types.