Strength, Permeability, and Microstructure of Cement Treated Dredging Sand

The dredging sand taken from riverbeds mixing cement can be a potential solution to construct earth levees against annual floods in the Southern Vietnam. The strength, permeability, and microstructure of the dredging sand sample mixed with the OPC cement (soilcrete) at various cement contents of 200, 250, 300, 350, and 400 kg/m³, respectively, were investigated. The soilcrete strength was tested following the ASTM D2166 standard. The soilcrete hydraulic conductivity was determined using the flexible wall permeameter applying the falling head method according to the ASTM D5084 standard. XRD and SEM–EDS examinations were carried out to observe soilcrete microstructure change. The results indicate that the strength and the permeability of the soilcrete specimens were significantly improved with increasing in curing time and cement contents. The soilcrete strength reached 6.13 MPa at a cement content of 400 kg/m³ at 28 days. The soilcrete hydraulic conductivity varied from 8.07 × 10⁻⁸ to 2.3 × 10⁻¹¹ m/s at the cement contents of 200 to 400 kg/m³. The soilcrere microstructure was denser to compare with the untreated sand. The products of CSH, ettringite, and portlandite were detected in the soilcrete specimens by the XRD and SEM–EDS analysis. These products developed with curing time and cement contents. The cementitious products filled voids and arranged as the frame and honeycomb structure which contribute to increase in strength and decrease in permeability in the soilcrete specimens.