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- LIBS (11)
- Concrete (6)
- Chloride (3)
- Chlorine (3)
- Heterogeneity (3)
- Alkali-silica reaction (ASR) (2)
- Carbonation (2)
- Chemical analysis (2)
- Chlorides (2)
- Sodium (2)
Organisationseinheit der BAM
The laser induced breakdown spectroscopy (LIBS) is a combination of laser ablation and optical emission spectroscopy. Due to the possibility of direct measurements on the sample surface and a minimum of required sample preparation investigations of building materials can be conducted quite fast. In combination with a scanning technique (translation stage or scanning mirrors head) the element distributions are evaluated taking in to account the heterogeneity of the material. This is a significant advantage compared to standard procedures. LIBS measurements are also time and cost saving in comparison to standard methods. The automated measurement procedures minimise the liability for errors. All elements are detectable and after calibration results can be quantified. At BAM LIBS has been successfully applied for the investigation of distribution and transport of different ions in building materials. Quantitative measurements are performed for chlorine, sodium, potassium, sulphur, lithium and hydrogen. Beside this the identification of substances and the evaluation of quantitative ratios by means of an integrated marker are possible. An overview about the principle and the possibilities of LIBS investigations of building materials is presented and typical applications are shown. The LIBS technique is on the step from laboratory application to on-site analyses.
Laser Induced Breakdown Spectroscopy (LIBS) is a combination of laser ablation, plasma formation and optical emission spectroscopy. The possibility of direct measurements on the sample surface, the minimum of necessary sample preparation and the automated setup allows for fast investigations of building materials. In combination with a scanning technique (translation stage or scanning mirrors head) the element distribution can be evaluated in consideration of the material's heterogeneity. LIBS measurements are also time-and cost-saving. The ingress profile of chlorine on a 50mm diameter concrete core up to a depth of 50mm can be measured and evaluated in less than 10 minutes. The results are normally referred to the evaporated mass, which is approximately the cement mass of the specific concrete. As a completion to micro XRF measurements also light elements like sodium or hydrogen can be detected. The spatial resolution of the measurement may reach 50 ìm at a maximum measurement frequency of up to 100 Hz. On the basis of calibration curves, results can be quantified.
Laser induced breakdown spectroscopy (LIBS) - visualization of ion transport processes in concrete
(2014)
Laser induced breakdown spectroscopy (LIBS) is a combination of laser ablation and optical emission spectroscopy. Due to the possibility of direct measurements on the sample surface and a minimum of sample preparation investigations of building materials can be conducted quite fast. In combination with a scanning technique (translation stage or scanning mirrors head) the element distributions are evaluated with mm resolution. Thus the heterogeneity of the material may be considered. This is a significant advantage compared to standard procedures. LIBS measurements are also time and cost saving in comparison to standard methods. The automated measurement procedures minimize the liability for errors. All elements are detectable. Results can be quantified after calibration. At BAM LIBS has been successfully applied for the investigation of distribution and transport of different ions in building materials. Quantitative measurements are performed for chlorine, sodium, potassium, sulfur, lithium and hydrogen. In addition the identification of substances and the evaluation of quantitative ratios by means of an integrated marker are possible. An overview about the principle and the possibilities of LIBS investigations of building materials is presented and typical applications are shown. The LIBS technique is close to practical application on-site.
Laser-induced breakdown spectroscopy (LIBS) is a combination of laser ablation and optical emission spectroscopy. Due to the possibility of direct measurements on the sample surface with a minimum of sample preparation investigations of building materials can be conducted quite fast. In combination with a scanning technique (translation stage or scanning mirrors head) 2D element distributions of harmful species like chlorides and alkalis are evaluated with a sub-mm resolution. By scanning a surface of typically 100 mm x 100 mm the heterogeneity of the material may be considered. LIBS is capable to identify hot spots in element concentration with a resolution of 0.1 mm or even smaller. A LIBS-system for the on-site application on building materials is, in cooperation with system developers and companies which will use this technique for investigation on real structures, under test at BAM. We present an example. Further work will focus on providing guidelines to establish LIBS as a standard procedure for chemical investigations of building materials.
The laser induced breakdown spectroscopy (LIBS) gives an alternative to the standard techniques for the direct investigation of a building material. It utilize a high energy pulsed laser beam for ablation and vaporization of a small amount of material, a plasma is formed and the plasma radiation is investigated using optical emission spectroscopy. Due to the principal all elements are detectable during one measurement. In combination with a translation stage or scanner system the heterogeneity of concrete is considered in the results. Thus an element concentration may be correlated to the cement content. After calibration with a set of reference samples quantitative results are obtained. The system is automated and allows rapid measurements and minimizes the possibility of errors. At BAM a laboratory LIBS system has been successful applied for the investigation of transport processes of different ions in building materials. The spatial resolution of the measurement may rich 100 μm and the frequency of the measurements is 100 Hz. The concentration of chlorine, sulfur, carbon, sodium, potassium, lithium and hydrogen where quantitatively determined. A mobile system for on-site analysis on bridges or parking decks is available. It is a tool for the estimation of the condition of concrete structures and for quality assurance during concrete repair work on-site. In these work an overview of the possibilities of LIBS for automated investigation of building materials are given.
Laser-induced breakdown spectroscopy (LIBS) is a combination of plasma generation on the sample surface by a high power laser pulse and optical emission spectroscopy (OES). It is a direct measurement method without an extensive sample preparation. Concrete is a multi phase system. With LIBS it is possible to distinguish the different phases and based on that to correlate the chloride content to the cement mass. This is done by scanning the surface with a resolution of up to 0.1 mm. The high measurement frequency of 100 Hz or even higher allows the in-situ visualization of the chloride content over the measured area. With a calibration a quantification of chloride concentration is possible. As an example the LIBS measurement on a 50 mm by 70 mm area with a resolution of 0.5 mm and the visualization of the chloride distribution takes only 10 minutes. Additionally it is possible to evaluate the carbonation depth from the same measurement. Examples of practical application to determine the chloride-to-cement-content on concrete samples are presented. The possibilities and the limitations of LIBS are discussed.
Cracks are always present in reinforced concrete structures. In the presented research, influence of mechanical cracks on chloride ingress is studied. A compact reinforced concrete specimen was designed, mimicking the cracking behaviour of beam elements. Cracks of different widths were induced by means of mechanical loading. These cracked specimens were then subjected to weekly cycles of wetting and drying with NaCl solution. After the exposure, the specimens were cut, and chloride distributions were determined using Laser Induced Breakdown Spectroscopy (LIBS), an innovative technique which enables simultaneous determination of different elements with high spatial resolution and minimal specimen preparation. By combining element distributions of different elements, it is possible to discriminate between coarse aggregate particles, and the mortar matrix. It was found that the wider the crack is, the higher the ingress of chloride ions. This was, however, different for two tested concrete mixes. Due to highly inhomogeneous chloride distribution around the cracks, use of fine-scale experimental techniques for chloride mapping is advised, based on the presented study.
Die chemische Analyse von Beton gehört bei der Ermittlung des Ist-Zustandes von Stahl- und Spannbetonbauwerken zu den grundlegenden Untersuchungen bei der Zustandserfassung. Der tiefenabhängige Chloridgehalt sowie der Karbonatisierungsfortschritt müssen bei der Bewertung des Ist-Zustandes, beim Instandsetzungsbedarf und ggf. bei der Planung eines erforderlichen Instandsetzungskonzeptes mit einbezogen werden. Seit Mitte der 1990er Jahre wird an der Bundesanstalt für Materialforschung und -prüfung die laserinduzierte Plasmaspektroskopie (engl. Laser-induced Breakdown Spectroscopy) – kurz LIBS – stetig für die chemische Analyse von Beton weiterentwickelt. In diesem Beitrag wird der aktuelle Stand der Forschung/ Technik und der Normungsarbeit präsentiert, sowie zukünftig mögliche Anwendungen vorgestellt. Mit den aktuellen LIBS-Systemen (mobiles LIBS-System sowie kommerziell erhältliche Laborsysteme) ist es möglich den Chloridgehalt ortsaufgelöst in wenigen Minuten zu quantifizieren, sogenannte Elementlandkarten zu erstellen und somit die Elementverteilung innerhalb des Betons zu visualisieren. Durch das Scannen eines Bohrkernquerschnittes und der simultanen Erfassung von mehreren Elementen mit einer Messung, ist es zudem möglich, die Gesteinskörnung in den Messdaten zu identifizieren und den Chloridgehalt auf die Zementsteinmatrix zu beziehen. Fehlerquellen aus der Umrechnung der betonbezogenen Chloridgehalte können dadurch minimiert werden. Neben den Grundlagen von LIBS werden vor allem aktuelle Praxisbeispiele vorgestellt, die die aktuellen Möglichkeiten des Verfahrens veranschaulichen.
This paper will address the relevance of chloride measurements in practice for durability condition assessment and a description of the working principle of LIBS will be given. Examples of chloride profiles obtained by the common wet chemical analysis will be shown and compared with results from LIBS measurements as to demonstrate the accuracy of the LIBS-technique. The latter will be supported by clear graphs. In addition examples on the extra information resulting from measurements performed with LIBS for improvement of condition assessment and prediction will be shown.
The Laser-Induced Breakdown Spectroscopy (LIBS) is a laser spectroscopic method which allows a time efficient, minor-destructive, chemical analysis of materials. In principle all elements on the periodic table can be simultaneously analysed by using LIBS, regardless of the state of aggregation. LIBS offers numerous applications in the field of civil engineering; most importantly the analysis of building materials. This work will focus on the evaluation of concrete structures and harmful substances which can penetrate the concrete. A variety of information can be collected through LIBS. Determining the concentration of harmful substances like chloride, sodium or sulphur, the examination of the carbonation depth and the distinction between varying layers of materials (e.g. aggregates, cement paste, metals, etc.) are possible applications. All this information can be provided through one LIBS measurement in the form of a high resolution 2D element map, with resolutions up to 0.1 mm x 0.1 mm. To scan a concrete surface only an optical access is needed. To create a depth profile of an intruding substance the extraction of a drill core is necessary. Onsite measurements via LIBS can be conducted by using a mobile version of the LIBS system. Through using calibration curves LIBS allows not only the qualitative but also quantitative analysis of element concentrations. All those prospects make LIBS a trendsetting method to secure the integrity of infrastructures in a sustainable manner. A variety of examples which show the performance and results of LIBS analysis will be presented.