Strength improvement of clay subgrade soil stabilised with recycled concrete aggregate and granulated blast furnace slag

In this research, a combined method of chemical and physical stabilisation has been used to investigate the effect of using recycled concrete aggregate (RCA) and granulated blast furnace slag (GBS) in improving the strength properties of subgrade soil. A comprehensive series of compaction, uniaxial compressive strength (UCS) and California bearing ratio tests were performed on different mixtures. The results show that UCS values increased for clay subgrade with up to 20% RCA content and decreased after that. The subgrade soil with 20% RCA was treated with GBS to obtain the target uniaxial strength for stabilised subgrade soils. Also, the results obtained from investigating the effect of freeze–thaw cycle on the UCS of the optimum combination with different GBS content show that the F-T cycle reduces the value of the UCS from 32% to 53% after 12 F-T cycles.