Effects of fresh water exposure on chloride contaminated concrete

Due to its porous structure, concrete that is exposed to chlorides will eventually become contaminated through the various mechanisms of chloride ingress, such as diffusion and absorption. As the conditions of chloride exposure are continuously changing, the movement of chlorides can occur in and out of the concrete. However, these rates of chloride movement are not the same. For de-icing salt exposure, the rate with which chlorides enter concrete from salt splash is much faster than the rate the chlorides will be extracted by rainwater. It was found that continuous or cyclic exposure of chloride contaminated concrete to distilled water will decrease the chloride concentration at the surface of the concrete; however, the chloride in saturated concrete continues to diffuse inward. Essentially, once chlorides have contaminated concrete, the chlorides cannot be completely removed under normal service conditions. (C) 2000 Elsevier Science Ltd. All rights reserved.