Bound chloride ingress in alkali activated concrete

Alkali activated cementitious material (AACM) concrete and conventional concrete specimens of similar strength, developed for structural applications, were exposed to a 5% NaCl solution. Bound chloride concentrations (water and acid soluble) were determined up to 270 days of chloride exposure. Chloride diffusion profiles with depth and diffusion parameters C0 and Dc were derived from the data for water soluble, acid soluble and total bound chloride concentrations in order to develop long term chloride prediction relationships. The results show that the practice of using acid soluble chloride data for long term chloride predictions in conventional concrete is not valid for AACMs due to their low chemical binding capacity. Instead the physically bound chloride (water soluble) is more predominant in AACMs and is suitable for the chloride prediction models. Therefore, relationships of chloride diffusion parameters C0 and Dc with time have been derived for water soluble chloride. These correlate with total bound chlorides and are suitable for long term predictions of chloride concentrations for the design and maintenance of AACM concrete structures against corrosion.