Bram Desmet

Chloride penetration and carbonation in self-compacting concrete

In this research program, both the steady-state and the non-steady-state migration test are used to determine the chloride diffusion coefficient D (m2/s) of 8 different self-compacting concrete mixes and 1 reference, traditionally vibrated, concrete mix. Simultaneously, the carbonation behaviour of those mixes was investigated. Here fore, the carbonation depth was measured at regular points in time according to NT BUILD 357 (1989) and a carbonation constant A (mm/√year) was deduced. Concerning the chloride diffusion coefficient, test results revealed that the determination of the steady-state migration coefficient according to NT BUILD 355 (1997) is far from easy and question marks could be placed beside the corresponding diffusion coefficient but an explanation for the observed anomalies could not be found yet. The non-steady-state diffusion coefficient according to NT BUILD 492 (1999) was used in order to rank the different concrete mixtures. The carbonation constant could best be measured using an inflated CO2-concentration, resulting in a more linear behaviour of the carbonation depth in function of time. Besides, using this carbonation constant, results reveal that the concrete mixtures could be ranked in the same way as they were by the non-steady-state chloride diffusion coefficient.