Improving Physical and Mechanical Properties of Expansive Subgrade with Construction and Demolition Waste

Expansive subgrades are considered problematic soils in road pavements due to their poor engineering performance. This paper investigated the stabilization of an expansive subgrade with construction and demolition waste (CDW). In this regard, the soil was substituted with CDW in ratios of 4%, 8%, 12%, 16% and 20% and several experimental tests, involving consistency limits, swelling/shrinkage, compaction, unconfined compressive strength (UCS) and California bearing ratio (CBR) were performed on soil samples. In addition, a Pearson correlation matrix was constructed to indicate the degree of relationship between the investigated experimental parameters. The test results revealed that plasticity and swelling/shrinkage potentials of expansive subgrade decreased significantly with the increase of CDW content. The soil’s maximum dry density (MDD) increased, whereas the optimum moisture content (OMC) was reduced continuously with CDW. The UCS and CBR of expansive subgrade with a 20% CDW content improved by 122.43% and 434.22% after curing for 28 days, respectively. The findings highlight that CDW can be utilized in expansive subgrade stabilization as a sustainable alternative in greener road construction.