On the time dependency of the chloride migration coefficient in concrete

From studies of the chloride penetration behaviour in laboratory tests and real structures, a clear time dependency of the chloride diffusion coefficient is observed. In order to get insight in this complicated problem, laboratory tests were performed with the non-steady state migration test, described in NT BUILD 492, up to 5 years concrete age. The influence of the type and amount of cement and filler and the amount of water on the migration coefficient and the so-called age factor of 16 self-compacting concrete mixes (SCC) and four traditional vibrated concrete mixes (TC) were investigated.The capillary porosity was introduced as parameter to describe the influence of the concrete composition. An increasing capillary porosity leads to an increased non-steady state migration coefficient and a decreasing age factor.