Laboratory investigation of using sand-HDPE mixture as stabilized subgrade

Today, the use of plastic waste in highway and geotechnical engineering, especially in subgrade stabilization, is extensively examined. This study investigated the effect of using disposable high-density polyethylene (HDPE) chips in stabilized sandy subgrade. The impact of adding HDPE to the sand was investigated through the one-dimensional consolidation, the modified standard proctor (MSP), the California bearing ratio (CBR), and the direct shear test (DST). Adding HDPE to the sand reduced the maximum dry density of the mixture because of its low specific gravity, but the optimum moisture content did not markedly change. The incorporation of HDPE in the sand also promoted the shear strength of the mixture because of the frictional resistance and interlocking between the particles and enhanced the CBR of the sand-HDPE mixture up to 48.7%. Therefore, using HDPE chips in sand-HDPE mixtures for subgrade stabilization can significantly improve the shear strength characteristic of sandy subgrades and, thus, reduce road construction costs.