Non-steady-state chloride diffusion coefficients obtained from migration and natural diffusion tests. Part II: Different experimental conditions. Joint relations

The complexity of the process of chloride penetration in concrete makes it difficult to define a standard procedure in order to calculate diffusion coefficients. In this paper, an attempt to find joint relations between coefficients calculated from different procedures is made. As a first step, an empirical relation, that allows the conversion of a diffusion coefficient calculated from any experimental conditions to a reference condition (0.5 M NaCl and 90 days of duration of the test), has been developed and validated with different natural diffusion tests. This relation enables the comparison between different non-steady-state diffusion coefficients. As a second step, the equivalence between migration and natural diffusion tests has been undertaken from different series of migration tests, in steady and nonsteady-state, conditions. The final results have been presented in a graphical form in order to facilitate their application.