Stabilization of residual collapsible soil using hydrated lime

The construction of the flexible pavement layers depends on the geotechnical characteristics of the subgrade soil to support the vertical overburden pressure without collapse. This study determined the area’s collapse potential (CP) to characterize the soil’s subgrade and treat the problematic area with lime. Laboratory tests conducted on the failed portion of the road and the soil’s CP revealed that the soil was collapsible. Test results for station PTR3 showed collapsible behavior to be used as a subgrade material due to the highest CP (5.81%). The effects of lime were determined for stabilizing collapsible soils at different percentages by weight (0%, 3%, 5%, and 8%) to the problematic soil. The results suggested that CP reduced from 5.81 to 0.61%. So, at 8% lime, CP was below 1%, which indicated that lime provided better strength parameters. Moreover, the grain size of the soil showed that adding lime increased the coarse-grained portion of the soil and decreased the fine-grained portion of the soil; consequently, the permeability of the soil increased.