Datei im Netzwerk der BAM verfügbar ("Closed Access")
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- 2017 (2) (entfernen)
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- Englisch (2)
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- LIBS (2)
- Building materials (1)
- Chemometrics (1)
- Chlorine (1)
- Concrete (1)
In order to determine the remaining life-time of reinforced concrete infrastructure like marine constructions, bridges or parking decks a fast and reliable detection of harmful species is necessary. If, as an example chlorine exceeds a specific concentration threshold, the result can be pitting corrosion of the reinforcement, which affects the stability and lifetime of building structure. In cooperation with industrial partners and BAM a mobile LIBS system for the on-site measurements has been developed. The mobile system uses a low energy laser with a pulse energy of 3 mJ and a NIR-spectrometer in combination with a scanner for two-dimensional mapping (140 x 170mm).
This work presents the mobile LIBS system, the calibration and an on-site applications in a parking garage. A correlation between surface measurements on a parking deck and ingress profiles obtained due to concrete cores are presented. LIBS results using the mobile LIBS system are able to provide in-time information about the Cl concentration and can therefore be used for quality assurance during reinstatement work.
For the damage assessment of reinforced concrete structures the quantified ingress profiles of harmful species like chlorides, sulfates and alkali need to be determined. In order to provide on-site analysis of concrete a fast and reliable method is necessary. Low transition probabilities as well as the high ionization energies for chlorine and sulfur in the near-infrared range makes the detection of Cl I and S I in low concentrations a difficult task. For the on-site analysis a mobile LIBS-system (k = 1064 nm, Epulse ≤ 3 mJ, t = 1.5 ns) with an automated scanner has been developed at BAM. Weak chlorine and sulfur signal intensities do not allow classical univariate analysis for process data derived from the mobile system. In order to improve the analytical performance multivariate analysis like PLS-R will be presented in this work. A comparison to standard univariate analysis will be carried out and results covering important parameters like detection and quantification limits (LOD, LOQ) as well as processing variances will be discussed (Allegrini and Olivieri, 2014 [1]; Ostra et al., 2008 [2]). It will be shown that for the first time a low cost mobile system is capable of providing reproducible chlorine and sulfur analysis on concrete by using a low sensitive system in combination with multivariate evaluation.