Durability of Mortars Made with Recycled Fine Aggregates Exposed to Sulfate Solutions

Abstract

This paper describes the resistance of mortar specimens with two different recycled fine aggregates when they were exposed to sodium and magnesium sulfate solutions up to 15months. The important difference between the recycled fine aggregates used in this study was the water absorption. Control mortar specimen made with only river sand was also tested to compare the degree of deterioration by sulfate attack. The tests include visual examination, compressive strength ratio, expansion and mass loss, as well as microstructural observations. The experimental data indicated that the use of 50% replacement level of recycled fine aggregates led to the increased or similar resistance to both sodium and magnesium sulfate attacks. At the 100% replacement level, however, mortar specimens containing recycled fine aggregate with higher water absorption suffered serious damage in mechanical properties, and the deterioration degree is likely to be more pronounced with further exposure. This work suggests that the absorption characteristics and replacement levels of recycled aggregates have a decisive influence on the sulfate resistance of mortar specimens.