Penetration profile of chloride ion in cracked reinforced concrete

A detailed observation on the penetration profile of chloride ions through and around a crack in reinforced concrete structures was carried out. Electron probe microanalysis (EPMA) and colorimetric tests were conducted on cracked specimens, which were exposed to NaCl solution at a temperature of 20 °C and a humidity of 60% RH, after being conditioned in the same condition for 2 months. Research parameters included water to cement ratio (w/c), single and multicracks, exposed direction, crack width, NaCl solution concentration and cover thickness. Increasing w/c led to a higher ingression rate of Cl⁻ ions, not only from the exposed surface but also around the cracks. It was found that the penetration depth from the surface of the cracks was equal to or slightly higher than that from the exposed surface for higher w/c mixes of 0.45 and 0.65. The transportation of Cl⁻ ion was strongly influenced by the bulk movement of the solution inside the concrete.