D. Mori, K. Yamada, Y. Hosokawa and M. Yamamoto
Journal of Advanced Concrete Technology, 4(3) 369-383, 2006
Electron probe microanalysis (EPMA) has been
applied for the quantitative evaluation of Cl ingress into concrete. In order to
obtain quantitative data on Cl concentration, the measurement conditions were discussed
statistically in detail and sample measurement conditions were introduced. The absolute
concentrations of Cl obtained through EPMA were found to be equivalent with wet analysis
and the effect of matrix differences to be negligible. By using the difference in
chemical composition between cement paste and aggregate measured by EPMA with a spatial
resolution of 100 m, it was possible to discriminate the paste part in concrete.
Since Cl penetrates into concrete through the paste part, the Cl concentration profile
obtained by EPMA is useful for the estimation of the apparent Cl diffusion coefficient,
Da. The quantified value of Cl concentrations obtained with EPMA were confirmed through
comparison with traditional slicing and grinding methods. Based on the measurement
results, the Da value was calculated for various concrete mixtures and the results
were found to be equivalent with those yielded by conventional methods.