Shrinkage reducing admixtures (SRAs) can alter ionic movement in concrete by changing the properties of pore fluid.This study examines the influence of SRA on chloride binding and diffusion.SRA was found to have little influence on chloride binding.However, as the concentration of SRA increased, the viscosity of the pore fluid increased thereby reducing chloride ion penetration.The apparent chloride diffusion coefficient is proportional to the reciprocal of the viscosity of the concrete pore solution.The apparent chloride diffusion coefficient in concrete with SRA can be estimated from that of plain concrete and the concentration of SRA in concrete pore solution (as the concentration is related to viscosity).