Chloride ingress data from field exposure, at twelve different marine exposure locations, and laboratory exposure

Rapport, 2003

Concrete specimens, made from one single concrete composition and under identical conditions, have been exposed at different exposure sites around the world. The exposure has mainly been made in marine submerged conditions, i.e. below the surface of the water, to get well-defined exposure conditions. Specimens have also been exposed in marine tidal conditions and along a thaw-salted road. Parallel with the field exposure specimens have been exposed in salt-solutions, with different chloride concentrations and temperatures, in the laboratory. Four or five specimens have been exposed on each site to get a measure of the scatter in chloride ingress. The duration of all exposures has been approximately one year. After finalised exposure the specimens have been analysed for chloride and calcium content (acid-soluble) in depth intervals from the surface. The analyses have been made on dust-samples achieved by means of profile grinding of cores drilled from the specimens. The chloride ingress has been measured as chloride ingress profiles, where the quotient between chloride and binder content is given in depth-intervals. The binder content has been estimated from the analysed calcium content, since the content of acid soluble calcium in the aggregates in the exposed concrete composition is negligible. Additionally chloride-binding isotherms (as free-bound and free-total chloride content) have been determined for the concrete composition used in the exposure programme. The measured chloride ingress profiles have been evaluated with the error-function solution of Fick’s second law to derive apparent chloride diffusion coefficients, DF2, and surface chloride contents, Csa. Two additional parameters have been collected to describe non-Fickian behaviour of the profiles, thicknesses of the “convection-zones” (where the profiles do not fit to the error-function), xc, and surface chloride contents for the diffusion-zones, Csc. Additionally the areas below the chloride ingress profiles have been determined to get an estimate of the amount of chlorides that have penetrated into the concrete. In this report the exposure programme is summarised. The concrete specimens (concrete composition and dimensions) and the exposure locations (geographical locations and exposure conditions) are described. The measurement techniques are briefly described and the results are presented as chloride ingress profiles. Furthermore parameters evaluated from and areas below the profiles are presented. The parameters and areas have also been statistically analysed to get mean values and standard deviations.