| Exposure of concrete to chloride ions is considered to be the main cause of premature corrosion of steel reinforcement. Cracking is an inevitable characteristic of reinforced concrete structures. Although, it is generally recognized that cracks promote the ingress of chlorides in concrete, a lack of sufficient knowledge on this subject does not yet allow reliable quantification of their effects. In the current study, the influence of artificially created, parallel-wall cracks with widths ranging from 0.06 to 0.74 mm on chloride ingress was examined. The effect of crack wall surface roughness was also evaluated. Based on the results of the chloride bulk diffusion test and SEM/EDX analysis, it was concluded that chloride diffusion in concrete was independent of either crack width or the crack wall roughness for the ranges studied. The transecting, parallel-wall cracks were found to behave like a free concrete surface, resulting in a case of two-dimensional diffusion and greatly promoting chloride ingress. A 2D simulation approach was proposed for predicting the chloride concentration profile in this case. It was also found that coarse aggregate contributes to chloride transport, likely due to percolating interfacial transition zones. A relationship between the depth of chloride penetration and time for both cracked and uncracked concrete was studied, as well. |
