The diffusion of ions through water-saturated cement

The interdiffusion of l^? and Cl^? ions and the tracer diffusion of Cs⁺ ions in watersaturated Ordinary Portland Cement have been measured at 30° C as a function of water/ cement ratio at fabrication. The diffusion was strongly influenced by the water/cement ratio in an approximately exponential manner and the Cs⁺ ions were significantly less mobile than the other ions. Diffusion measurements and electrical conductivity measurements have also been made as a function of temperature and reveal that significant irreversible changes in pore structure were induced on heating. The implications of the observations for the diffusion mechanism and the probable pore structure of the cement paste are discussed.