Lightweight fill using sand, polystyrene beads and cement

Abstract

A laboratory study on the formation of a lightweight fill material for embankments on weak soils is reported in this paper. The proposed material is made by blending sandy soil with expanded polystyrene beads and a stabilising material such as cement. The effects that the different compositions and ratios between the beads and cement mixed with sand have on the maximum dry density, optimum moisture content, ultimate shear stress and angle of internal friction of the lightweight mixture were studied. It was observed that the density of the lightweight mixture can be effectively controlled by the amount and density of beads used. With the inclusion of 0·3 to 3% of beads (to sand by weight), the bulk density of the lightweight mixture formed can be reduced to 0·85–1·8 kg/m3. The shear strength and stiffness of the lightweight mixture can be controlled by adjusting the amount of cement used. Cement was used to compensate for shear strength losses due to the addition of beads in the ratio of 3 to 10% (by sand weight). Adding cement to the beads and sand mixture increased the shear strength parameters and maximum dry density and decreased the optimum moisture content.