Improved chloride transport resistance of cement mortar using quartz sands modified with MgAl-LDH

The chloride transport into concrete is responsible for the durability deterioration of concrete under chloride-laden conditions. This paper aims to restrict the chloride transport into mortar by the partial replacement of fine aggregates with the quartz sands modified by MgAl-LDH, which were prepared by the co-precipitation method. The microstructures of modified sands and mortars were characterized. Besides, the chloride transport properties in mortar were evaluated by the rapid chloride migration test and long-term chloride diffusion test. The results indicate that quartz sands with in-situ-growth MgAl-LDH have improved specific surface area and chloride binding capacity. With the replacement ratio of modified sands increasing, the resistance of mortar against chloride penetration is significantly improved. The reason for the improved chloride transport resistance may be due in part to the improvement of the microstructure of ITZ, but more importantly, to the chloride ions immobilization of the modified quartz sand.

Automated summary

This paper aims to restrict chloride transport into mortar by partially replacing fine aggregates with quartz sands modified by MgAl-LDH. The results indicate that the modified quartz sands with in-situ-growth MgAl-LDH have improved specific surface area and chloride binding capacity. With the increase in replacement ratio, the resistance of mortar against chloride ion penetration is significantly improved.