Influence of pores on the corrosion and cracking of the reinforced concrete suffered by the chloride ions and stray current

This paper investigates the reinforced concrete specimens embedded in a chloride environment and stray current by Computerised X-ray tomography (CT). The distribution of pores, corrosion, and cracks in concrete specimens corroded in the aggressive environment was statistically analysed, and the variation in the crack morphologies was studied. A grey correlation analysis was employed to assess the relationships among porosity, corrosion, and cracking. The results reveal that pores are primarily concentrated in the top section of the specimens, followed by the bottom and then the side sections. This pattern of distribution is due to combined effects of reinforcement bar layout and concrete densification during casting. The crack convergence is caused by the merging of multiple corrosion-induced microcracks near the steel interface. After crack convergence, the width of the external crack increases while the width of the internal crack remains stable. The presence of reinforcement bar significantly affects the distribution of pores in concrete, which in turn influences the extent of reinforcement corrosion. Regions with higher porosity in the concrete show more reinforcement corrosion and concrete cracking. Based on the tested specimens, the pore characteristics of concrete have a greater effect on cracking than reinforcement corrosion. The effect of pore number on crack is greater than that of pore area fraction. This study highlights internal degradation features relevant to service performance. It also offers insights for durability design of concrete structures in aggressive environments.