Effect of aggregates spatial distribution on three-dimensional transport of chloride ions in reinforced concrete

Abstract

The spatial distribution of coarse aggregates directly affects the three-dimensional transport of chloride ions and the accumulation of chloride ions on the surface of steel bar in reinforced concrete. The meso-structure of a concrete specimen was recognized through X-ray CT technology. In considering the diffusion of chloride ions both in mortar matrix and ITZs, a three-dimensional transmission model was established to numerically simulate the diffusion of chloride ions in concrete, which was furtherly verified by electronic microprobe technology. To avoid the correlation of data, 100 sets of independent three-dimensional numerical samples were generated with real coarse aggregates extracted from concrete specimen. The influence of spatial distribution of coarse aggregates on diffusion of chloride ions was statistically analyzed, and the differences between three-dimensional transmission and two-dimensional transmission of same sections were studied. The research shows that the special distribution of coarse aggregates can cause the non-uniform distribution of chloride ions both in spatial and time scale. The concentration distribution of chloride ions satisfies the Normal distribution through Kolmogorov-Smirnov test and Chi-square test. For two-dimensional and three-dimensional transmission, the greater the depth, the greater the differences in calculation results.