Preliminary study on lightweight fill mixtures of EPS beads and sand for geotechnical applications

Abstract

Vietnam is facing a shortage of sand fill material for infrastructure construction, especially in soft soil regions such as Ho Chi Minh City and the Mekong Delta. To reduce the load from embankments and road foundations, a lightweight mixture of sand and expanded polystyrene (EPS) beads is considered in this preliminary study. Two volumetric ratios of EPS to sand (0.5 and 0.7) were prepared. The maximum dry unit weight was determined from Standard Proctor tests, and direct shear tests were conducted on specimens prepared at the maximum dry unit weight to obtain the shear strength parameters. The mixtures showed a clear reduction in maximum dry unit weight when EPS content increased. Variations in shear strength parameters were also observed, indicating that the mechanical behavior of the mixtures depends strongly on EPS to sand ratios. The results suggest that EPS – sand mixtures could be an alternative fill material for soft ground projects in Vietnam, though further studies on mixture optimization, binder addition, and large-scale performance are needed.