Improving geotechnical properties of soil of hillock slope using crushed recycled concrete aggregates

Abstract

With the massive expansion of urbanization worldwide, a huge volume of construction and demolition waste (CDW) generation has become a common issue along with CDW from controlled demolition and earthquakes, which causes a tremendous headache for environmentalists. Moreover, sliding and failure of the slope of hillocks, hills, roads, and earthen dams raise concerns for geotechnical engineers. Among the several methods of improving the geotechnical behaviour of soil of the slopes, this research utilized CDW-based recycled concrete aggregates (RCA) to improve slopes of two hillocks named GK and BH. The crushed RCA was applied in various percentages, 5–35 %, in the soil mass and as a circular column to observe the improvement of the soil's geotechnical properties that largely influence slope stability. RCA column, a sustainable alternative to the sand, stone, or other natural materials column, can work as a vertical drain with an improved permeability of slope geo-material to improve infiltration. The soil samples with 30 % RCA mixed and RCA columns inserted into the soil mass resulted in lower consolidation settlement, compressibility index, and higher shear strength parameters. Moreover, 30 % RCA column increased the permeability by 6 and 7-times for the hillocks GK and BH, respectively, which reduces the chance of excess pore water pressure (PWP) development that can trigger the failure of a slope. Improving soil properties with recycled concrete aggregates can be a sustainable way to solve weak soil and failure issues of low-permeable low-height natural hillocks.