Diffusion and sorption-coupled transport of contaminated ground water in mineral sealing composite

A simple technique has been developed for measuring the ionic ingress into the surface layers of sealing composite specimens exposed to a salt solutio n, from which the apparent diffusivities for chloride, sulphate, sodium, an d potassium are derived. Results obtained have indicated that for a given c omposite, the depth of the ion diffusion is dependent upon the age of the s pecimens. If the sealing composite is older than about 2 years, i.e., the c hanges in its chemical compositions and microstructures are negligible comp ared to the rate of penetration of the ions, the apparent diffusivities det ermined from the diffusion equation according to the second Fick's law can realistically characterise the diffusion and sorption-coupled transport of ions into the mineral sealing composite materials.