Utilization of concrete waste from demolition sites in pavement subgrade

Abstract

The direct use of recycled waste concrete (RWC) is difficult as the demolished concrete shows large variation of raw materials and higher rate of water absorption due to the porosity of the lumps. Owing to such reasons, the utilization of the RWC is difficult for structural applications; however, it may be interesting to explore the feasibility of using RWC in non-structural applications such as subgrade layer of pavements. In this research work, the demolished concrete has been recycled with nominal crushing treatment in a ball mill and separated as fine powder, small to medium size aggregates. The soil samples have been prepared consisting soft clay (SC) type subgrade soil with all three forms of RWC in equal proportions. The SC has been replaced from 0% to 70% by weight with the blended RWC. Tests for the subgrade characterization namely California Bearing Ratio (CBR) values, dry density, moisture content, and plate load tests have been conducted. Under all test conditions, the addition of the RWC into the SC soil showed improvement at a given fraction of replacement. The work supported the feasibility of the utilization of the RWC for preparing the subgrade layer for the pavements and promoting the sustainability of the waste concrete in the civil engineering applications.