Chloride ingress and carbonation in concrete exposed to cyclic wetting and drying

Carbonation and chloride ingress are the two main causes of corrosion in reinforced concrete structures. An investigation to monitor the ingress of chlorides and carbonation during a 9 month wetting and drying exposure regime to simulate conditions in which multiple mode transport mechanisms are active was conducted on a variety of binders. The penetration was evaluated using water and acid soluble chloride profiles, and phenolphthalein indicator. X-ray diffraction was also used to determine the presence of bound chlorides and carbonation. The results indicated that acid extraction of chlorides is quantitatively reliable and practical for assessing penetration. The effect of carbonation on binding capability was observed and the relative quantity of chlorides also showed a correlation with the amount of chlorides bound in the form of Friedel’s salt.