Study on Chloride Diffusion Behaviors of Recycled Concrete of Random Aggregates

Abstract

Based on the chloride ions (Cl−) diffusion model and aggregate grading theory, PYTHON and COMSOL are used to construct a mesoscopic model of recycled concrete random polygon aggregate and verify its validity in combination with existing experimental results. The diffusion law of Cl− in recycled concrete and the law of influence of critical factors on the Cl− erosion resistance are studied by calculating and analyzing the Cl− erosion resistance of recycled concrete under different working conditions such as the diffusivity of new and old mortar, the thickness of old mortar and the replacement ratio of recycled aggregate. The results show that the simulation results agree well with the test results, and the method can better reproduce the Cl− diffusion process inside the recycled concrete. There are discontinuous features based on the relationship curves between the Cl− concentration and the depth of the recycled concrete. The Cl− concentration inside the concrete gradually increases with the increase of the diffusion rate of the old and new mortars. The resistance behavior of the recycled concrete to Cl− attack decreases with the increase of the thickness of the old mortar.