Chlorine determination in a concrete matrix using orthogonal double-pulse laser-induced breakdown spectroscopy

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Reinforced concrete is the worlds most used material for civil engineering. Concrete normally contains a small amount of chlorine which is strictly controlled by relevant standards. However, the total chlorine content varies depending on conditions in different environments. Because of its porous structure, chloride ions can diffuse through concrete to steel reinforcement rods. It leads to lifetime shortening because of corrosion of reinforcement, which is one of the most common problems in reinforced concrete buildings. This paper uses double-pulse laser-induced breakdown spectroscopy (LIBS) for chlorine determination in concrete. LIBS is an analytical method and provides quick determination of different elements. This method is based on a laser with high energy, which is focused on a sample surface in small area. Analysis of halogens is problematics because all halogens have high excitation energy lines. For this reason, the double-pulse LIBS is used. Another commonly used method how to determine chlorine content is potentiometric titration, which requires sample preparation. LIBS can be used in-situ, with minimal sample preparation and non-destructive analysis. For chlorine determination, orthogonal double pulse LIBS configuration is used. Optimization was done in a helium atmosphere. To maximize the intensity of the chlorine line Cl I 837.59 nm, the energy of both lasers, gate delay and interpulse delay has been set. After the optimization calibration dependence was constructed. Used statistical method was leave one out. The experimental and data processing optimization lead to an improved limits of detection and accuracy of quantitative analysis

double-pulse laser induced breakdown spectroscopy; concrete; chloride corrosion

KRATOCHVILOVÁ, L.; PROCHAZKA, D.; POŘÍZKA, P.; NOVOTNÝ, K.; HRDLIČKA, A.; KAISER, J.

1. 12. 2021