Chloride permeability of recycled aggregate concrete under the coupling effect of freezing-thawing, elevated temperature or mechanical damage

Abstract

Chloride penetration frequently leads to a steel corrosion and reduces the durability of reinforced concrete. Although the previous studies have investigated the chloride permeability of recycled aggregates concrete (RAC), the chloride permeability of RAC with pre-damage received little considerations. Considering that the RAC may be subjected to various exposure environments, this paper focused on exploring the chloride permeability of RAC under the coupling effect of freezing-thawing, elevated temperature or mechanical damage. The freezing-thawing, elevated temperature or applied loading test was first employed to induce initial damage on RAC, and then the chloride diffusivity test was conducted on RAC with various pre-damages. The findings showed that the chloride permeability of RAC increased with increasing recycled coarse aggregate (RCA) content. Exposing to harsh environment, the incorporation of RCA increased the freezing-thawing, elevated temperature or mechanical damage of RAC. The chloride permeability increased with increased initial damage, and a good relation could be observed between them. The incorporation of RCA improved the sensitivity to the chloride permeability of RAC exposed to harsh environment; such as, the chloride diffusion coefficient of RAC with 100% RCA was 51.4% higher than that of the plain concrete without pre-damage, while the results were 233.3% and 62.1% after 75 freezing-thawing cycles and 80% fc.