Using micro X-ray fluorescence to image chloride profiles in concrete

Corrosion of steel reinforcement in concrete is not easy to detect until cracking has initiated. When there is a question about Cl intrusion into concrete, cores are taken, the sample is ground in controlled thicknesses, and then the powder is analyzed by titration. This paper uses micro X-ray fluorescence (μXRF), a non-destructive chemical imaging technique, to obtain equivalent or better information than profile grinding methods with less human involvement. Fifteen different comparisons are made between profile grinding and μXRF from the same concrete and the results are comparable. Examples are also presented where the spatial measurements made by μXRF provide insights that are not possible with the conventional profile grinding method. This means the Cl profile can be obtained with μXRF with less human effort while providing additional insights not possible with the typical profile grinding analysis.