Mesoscale simulation of chloride penetration in recycled aggregate concrete based on random convex polygon aggregate model

Abstract

The durability of recycled aggregate concrete (RAC) in the marine environment is mainly influenced by chloride attack. In this paper, the chloride transport law in RAC with different recycled coarse aggregate (RCA) contents was investigated by dry-wet cycling tests considering RCA volume fractions. A five-phase randomly convex polygonal aggregate model was built through a self-compiled program and then a mesoscopic numerical method was established by finite element software development. The proposed numerical model was validated by experimental results and data from other scholars. The impact of interfacial transition zone (ITZ), RCA, new mortar and old mortar were studied. The results showed that: 1) As the thickness of ITZ grows, the chloride diffusion coefficient increases in RAC. When the thickness of the ITZ rises from 25 µm to 100 µm, the chloride diffusion coefficient rises by 37%; 2) The diffusion coefficient of ITZ and mortar have a positive impact on the diffusion of chloride ion in RAC; 3) The chloride diffusion coefficient of RAC is positively correlated with the volume fraction of RCA (VRCA). The chloride diffusion coefficient increases by 102.0% as the VRCA increases from 0% to 50%. The proposed mesoscopic model not only effectively simulates the chloride attack process but also can be used to simulate other ionic attack behaviors and mechanical properties of RAC.

Keywords

• Dry-wet cycling tests
• Recycled aggregate concrete
• Chloride
• Random convex polygon aggregate model
• Mesoscopic numerical analysis