Effects of Drying-Wetting Cycles on Durability of Carbonated Reactive Magnesia-Admixed Clayey Soil: Fid-Bau Portal

Effects of Drying-Wetting Cycles on Durability of Carbonated Reactive Magnesia-Admixed Clayey Soil

Cai, Guang-Hua / Liu, Song-Yu / Zheng, Xu

The durability of ${CO}_{2}$ -carbonated reactive magnesia (MgO)-admixed clayey soils against drying-wetting cycles has not been well understood now despite the fact that the engineering properties of ${CO}_{2}$ -carbonated MgO-admixed soils have been extensively investigated in previous studies. This paper presents the details of a study of the effects of drying-wetting (D-W) cycles on the physical, chemical, mechanical, and microstructural properties of ${CO}_{2}$ -carbonated MgO-admixed clayey soils, and ordinary portland cement (PC)-stabilized soils used as a control sample for comparison. The results indicate that compared with PC-stabilized soils, the soundness ranks and pH of ${CO}_{2}$ -carbonated MgO-admixed clayey soils have varying degrees of decline after drying-wetting cycles and ${CO}_{2}$ -carbonated MgO-admixed clay has a higher mass change ratio and water content than carbonated MgO-admixed silty clay. The residual strength ratios of ${CO}_{2}$ -carbonated MgO-admixed and PC-stabilized clay were 0.35 and 0.65, respectively, whereas the residual strength of ${CO}_{2}$ -carbonated MgO-admixed silty clay still was higher than that of PC-stabilized silty clay, although their residual strength ratios both were above 0.8. The elasticity modulus of ${CO}_{2}$ -carbonated MgO-admixed clay decreased from 260 to 100 MPa after one drying-wetting cycle and was less than that of ${CO}_{2}$ -carbonated MgO-admixed silty clay ( $\sim 400 MPa$ ), showing weaker and better durability against drying-wetting cycles of ${CO}_{2}$ -carbonated MgO-admixed clay and of silty clay, respectively. Microstructural analyses confirmed the physical, chemical, and mechanical results.