Influence of time dependency of chloride diffusion coefficient on resulting service life of concrete structures

The chloride diffusion coefficient of concrete is strongly decreasing in time. Neglecting this aspect in the modelling of the diffusion process will overestimate the chloride penetration depth and thus lead to an uneconomic design. In order to get an accurate insight in this decreasing process, 16 self-compacting concrete mixes (SCC) and 4 traditional concrete mixes (TC) were made. Four types of cement, three types of filler and two types of coarse aggregate are used and the influence of the amount of powder and the amount of water is studied. The chloride migration coefficient was experimentally determined with the non-steady state migration test, developed by Tang et al. and described in NT BUILD 492, and making use of an electrical field. This migration coefficient was determined at different concrete ages, up to 5 year. From the migration tests, the diffusion coefficients were deduced. The decrease in time of diffusion coefficients is studied and modelled. In a previous study of the authors, relations are obtained for the age factor and the non-steady state migration coefficient in function of the capillary porosity. Both relations are used to study the influence of the time dependency of the diffusion on the resulting service life.

ISBN:9781904482604

Jaar van publicatie:2009

Toegankelijkheid:Closed