Neues DGZfP-Merkblatt B14: Quantifizierung von Chlorid in Beton mittels LIBS

In the maintenance of reinforced concrete structures, the chloride content in the concrete is an important parameter in determining suitable repair measures. Established methods to date are based on wet chemical analysis of concrete samples; drill flour or ground segments of drill cores. These methods provide one chloride content per depth segment, which is associated with a strong homogenisation of the sample, resulting in a loss of details of the chloride differences in the range of a few millimetres. An alternative method is the laser-induced breakdown spectroscopy (LIBS), which not only enables the quantitative, spatially resolved determination of the chloride content in relation to the cement mass, but also provides detailed information on the distribution of many other chemical elements simultaneously. Usually the spatial resolution is in the range of a few millimetres but can be increased to 0.1 mm or smaller if needed. The new guideline B14 “Quantification of chloride in concrete using laser induced breakdown spectroscopy (LIBS)” of the German Society for Non-Destructive Testing (DGZfP) regulates and standardises for the first time the procedure to ensure a reliable and reproducible determination of chloride contents using LIBS. This article introduces the guideline and illustrates the potential of LIBS for issues in concrete maintenance.