The Moisture Effect on the Diffusion of Chloride Ion in Hydrated Cement Paste

Previous research [1] showed high chloride concentrations (2% / cement) on the outside surface of reinforced concrete structures in the mist zone of marine environments. However, the chloride penetration reaches low depths for the concrete class used. Observed data have raised suspicions as to the effect of moisture content on the diffusion of chlorides. A test method was developed to assess the changes in the chloride diffusion coefficient with changes in moisture content in cement paste. It was concluded that the saturation degree (SD) (percentage of moisture content in the cement paste in relation to maximum water absorption of the cement paste) has a large influence in the chloride diffusion properties of the hardened cement paste, and this factor must be taken into consideration when predicting the service life of a reinforced concrete structure.