California Bearing Ratio (CBR) Behaviors of EPS Geofoam: Experimental and Numerical Studies

Expanded Polystyrene (EPS) geofoam is ultra-lightweight, closed cell, rigid, plastic foam. It can be used for lightweight fill, compressible inclusion, thermal insulation, drainage and so forth. An experimental study was carried out to investigate the California bearing ratio (CBR) behavior of EPS geofoam. Three different densities of EPS geofoam 12, 15 and 20 kg/m³, and six different piston sizes (0.75D, D, 1.2D, 2D, 2.3D and 2.6D) where D is diameter of standard piston were used for standard CBR sample size. Moreover, in the present study CBR of EPS geofoam is investigate at dry and submerged in water conditions. The effect of piston diameter and density on the CBR values of EPS geofoam were investigated. The study revealed that increase of density of EPS geofoam resulted in an appreciable increase in the CBR value. The CBR test results were found to be 0.87, 1.67, and 1.86% for 12, 15 and 20 kg/m³ densities of EPS geofoam respectively at 2.5 mm penetration with standard piston size. The test result shows that the CBR value increased with an increase in density of EPS geofoam, however, the effects of CBR values were not more pronounced between dry and wet test conditions. The benefit of increasing or decreasing piston diameters beyond 50 mm does not improve the CBR value appreciably. An increase in density is more effective than an increase in piston diameter in improving the CBR value of the EPS geofoam. It is observed that the CBR value of EPS geofoam is very less and equivalent with clay soils. The density of EPS geofoam used for the construction of pavements should be more than 15 kg/m³ concerns related to the quality and the durability of the material. Finite element analysis was also carried out using PLAXIS 2D software to validate with experimental results. A reasonable agreement was observed between the numerical and experimental studies on pressure-displacement response.