Effect of Loading and Carbonation on the Compressive Strength and Hydraulic Conductivity of Solidified Sand

Cement-based solidification/stabilization (S/S) techniques have been widely used to produce stable forms of contaminated soils and reduce the mobility of contaminants into the environment. However, information on the long-term performances of S/S under environmental conditions (i.e., variable loading and atmospheric carbon dioxide) remains sparse. In this study, a triaxial test setup was modified to simulate environmental conditions. The permeability and compressive strength of silica sand solidified with portland cement were measured at different stages of four scenarios involving carbonation only, axial strain only, carbonation followed by axial strain, and axial strain followed by carbonation. X-ray computed tomography (CT) was used to characterize the internal structure of the samples. Permeability and compressive strength results indicate that the axial strain accelerated the damage to the S/S specimens and increased their permeability. The deterioration due to the mechanical strain decreased in the presence of carbon dioxide. Consistent changes in microstructure were observed with the CT scan. The results indicate that the influence of stressors on the void size distribution, compressive strength, and permeability is complex and characterized by interactions between the stressors.