TY - JOUR A1 - Weritz, Friederike A1 - Taffe, Alexander A1 - Schaurich, Dieter A1 - Wilsch, Gerd T1 - Detailed depth profiles of sulfate ingress into concrete measured with laser induced breakdown spectroscopy N2 - Sulfate attack constitutes a major risk of chemical aggression for concrete and other building materials. Mainly structures exposed to sewage waters and sulfate rich soils are affected. The measurement of sulfate ingress is important for damage assessment previous to repair works and for quality assurance of the effectiveness of protecting coatings or during concrete removal. Laser induced breakdown spectroscopy is introduced for the quantitative measurement of sulfur contents in building materials, providing detailed depth profiles and imaging element distributions with 1 mm spatial resolution. Detailed statistical evaluation is possible due to the spatial resolution and the fast measurement of the method. Practical applications of the method for damage assessment are demonstrated for three different sewage plants. KW - Laser induced breakdown spectroscopy KW - Sulfate attack KW - Sulfur content KW - Concrete KW - Sewage plant KW - Depth profiles KW - Element distribution PY - 2009 DO - https://doi.org/10.1016/j.conbuildmat.2007.12.016 SN - 0950-0618 VL - 23 IS - 1 SP - 275 EP - 283 PB - Elsevier Science CY - Amsterdam AN - OPUS4-18426 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Taffe, Alexander A1 - Wilsch, Gerd A1 - Schaurich, Dieter A1 - Weritz, Friederike T1 - Einsatz der Laser-Induzierten Breakdown Spektroskopie (LIBS) im Bauwesen - Teil 1: Verfahrensbeschreibung und Durchführung von Zementanalysen PY - 2004 UR - http://www.ernst-und-sohn.de/zeitschriften/artikelrecherche/index.php?zs=bst&t=Beton-+und+Stahlbetonbau+1970-heute+%28erscheint+monatlich%29&sort=hjd&page=1&bp=&bt=&bst=bst&mw=&dibt=&st=&bst_jahr=2004&bst_heft=8&absenden=%5BAuswahl+anzeigen%5D SN - 0005-9900 SN - 1437-1006 VL - 99 IS - 8 SP - 693 EP - 694 PB - Ernst CY - Berlin AN - OPUS4-4403 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Taffe, Alexander A1 - Wilsch, Gerd A1 - Schaurich, Dieter A1 - Weritz, Friederike T1 - Einsatz der Laser-Induzierten Breakdown Spektroskopie (LIBS) im Bauwesen - Teil 2: Ermittlung von bauschädlichen Salzen PY - 2004 UR - http://www.ernst-und-sohn.de/zeitschriften/artikelrecherche/index.php?zs=bst&t=Beton-+und+Stahlbetonbau+1970-heute+%28erscheint+monatlich%29&sort=hjd&page=1&bp=&bt=&bst=bst&mw=&dibt=&st=&bst_jahr=2004&bst_heft=8&absenden=%5BAuswahl+anzeigen%5D SN - 0005-9900 SN - 1437-1006 VL - 99 IS - 9 SP - 761 EP - 762 PB - Ernst CY - Berlin AN - OPUS4-4404 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wilsch, Gerd A1 - Weritz, Friederike A1 - Schaurich, Dieter A1 - Wiggenhauser, Herbert T1 - Determination of chloride content in concrete structures with laser-induced breakdown spectroscopy N2 - An important criterion for the evaluation of reinforced concrete structures is the measurement of the chloride content. This will normally be done by time consuming standard chemical methods. We propose the application of a spectroscopic technique, the laser-induced breakdown spectroscopy (LIBS), which provides the advantages of a fast measurement, the potential for on-site application and the possibility to investigate a wide range of different measuring points. The surface can be scanned, or depth profiles are available from cores. Measurements can be performed directly on the sample surface and the results are available in near real time. We present LIBS results measured on concrete cores as well as on grinded and pressed material in comparison with the results of standard chemical methods. The optimum LIBS set-up and the experimental conditions to detect and measure chlorine in building materials are reported. The limits of detection were determined and calibration curves were measured. KW - Chloride content KW - Reinforced concrete KW - Laser-induced breakdown spectroscopy KW - Near real time results KW - Non-destructive testing PY - 2005 DO - https://doi.org/10.1016/j.conbuildmat.2005.06.001 SN - 0950-0618 VL - 19 IS - 10 SP - 724 EP - 730 PB - Elsevier CY - Oxford AN - OPUS4-10830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weritz, Friederike A1 - Schaurich, Dieter A1 - Taffe, Alexander A1 - Wilsch, Gerd T1 - Effect of heterogeneity on the quantitative determination of trace elements in concrete N2 - Laser-induced breakdown spectroscopy has been used for quantitative measurement of trace elements, e.g. sulfur and chlorine, in concrete. Chloride and sulfate ions have a large effect on the durability of concrete structures, and quantitative measurement is important for condition assessment and quality assurance. Concrete is a highly heterogeneous material in composition and grain-size distribution, i.e. the spatial distribution of elements. Calibration plots were determined by use of laboratory-made reference samples consisting of pressings of cement powder, hydrated cement, cement mortar, and concrete, in which the heterogeneity of the material is increasing because of the aggregates. Coarse aggregate and cement paste are distinguishable by the intensity of the Ca spectral lines. More advanced evaluation is necessary to account for the effect of the fine aggregate. The three series of reference samples enable systematic study of the effects of heterogeneity on spectral intensity, signal fluctuation, uncertainty, and limits of detection. Spatially resolved measurements and many spectra enable statistical evaluation of the data. The heterogeneity has an effect on measurement of the sulfur and chlorine content, because both occur mainly in the cement matrix. Critical chloride concentrations are approximately 0.04% (m/m). The chlorine spectral line at 837.6 nm is evaluated. The natural sulfur content of concrete is approximately 0.1% (m/m). The spectral line at 921.3 nm is evaluated. One future application may be simultaneous determination of the amount of damaging trace elements and the cement content of the concrete. KW - LIBS KW - Heterogeneity KW - Concrete KW - Chlorine KW - Sulfur PY - 2006 DO - https://doi.org/10.1007/s00216-006-0362-0 SN - 1618-2642 SN - 1618-2650 VL - 385 IS - 2 SP - 248 EP - 255 PB - Springer CY - Berlin AN - OPUS4-12206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kääriäinen, H. A1 - Rudolph, Michael A1 - Schaurich, Dieter A1 - Tulla, K. A1 - Wiggenhauser, Herbert T1 - Moisture measurements in building materials with microwaves N2 - The method requires two parallel boreholes in the specimen in which two microwave antennae can be moved. The moisture content in the material can be calculated from the microwave intensity transmitted between the two boreholes. Moisture profiles along the boreholes can be obtained by moving the antennae in steps along the length of the boreholes and taking measurements at each step. The microwave frequencies used in the laboratory measurements ranged from 8 to 16.5 GHz in steps of 0.5 GHz. The diameters of the antennae were between 7 and 9 mm, and of the boreholes between 8 and 12 mm. The microwave method produced measurement uncertainties between 0 and 2% by volume for all the materials studied in this report. KW - Construction materials KW - Moisture transport KW - Moisture meter KW - Microwaves KW - Concrete KW - Sand KW - Wood PY - 2001 SN - 0963-8695 VL - 34 IS - 6 SP - 389 EP - 394 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-11049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weritz, Friederike A1 - Ryahi, Solh A1 - Schaurich, Dieter A1 - Taffe, Alexander A1 - Wilsch, Gerd T1 - Quantitative determination of sulfur content in concrete with laser-induced breakdown spectroscopy N2 - Laser-induced breakdown spectroscopy has been employed for the investigation of the sulfur content of concrete. Sulfur compounds are a natural but minor component in building materials. The ingress of sulfates or sulfuric acid constitutes a major risk of chemical aggression for concrete. There is a need for a fast method, which can be used on-site and is able to investigate a wide range of different measuring points, so that damages can be characterized. For quantitative determination the sulfur spectral line at 921.3 nm is used. The optimum ambient atmosphere has been determined by comparison of measurements accomplished under air, argon and helium atmosphere. Reference samples have been produced and calibration curves have been determined, the results of LIBS measurements are compared with results from chemical analysis. Defining a limit for the intensity ratio of a calcium and a oxygen spectral line can reduce the influence of the heterogeneity of the material, so that only spectra with a high amount of cementitious material are evaluated. Depth profiles and spatial resolved sulfur distributions are presented measured on concrete cores originating from a highly sulfate contaminated clarifier. KW - Laser-induced breakdown spectroscopy KW - Sulfur content KW - Building materials KW - Heterogeneity KW - Depth profiles PY - 2005 DO - https://doi.org/10.1016/j.sab.2005.05.036 SN - 0584-8547 SN - 0038-6987 VL - 60 IS - 7-8 SP - 1121 EP - 1131 PB - Elsevier CY - Amsterdam AN - OPUS4-10997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weritz, Friederike A1 - Schaurich, Dieter A1 - Wilsch, Gerd T1 - Detector comparison for sulfur and chlorine detection with laser induced breakdown spectroscopy in the near-infrared-region N2 - Laser-induced breakdown spectroscopy has been employed for the investigation of the sulfur and chlorine content of building materials. Both, chloride and sulfate ions are major damaging species affecting the stability and lifetime of a structure. Chlorine and sulfur are mostly detected in the VUV and the NIR. In case of building materials the main elements like calcium or iron have many strong spectral lines over the whole spectral range, so that trace elements can only be detected in spectral windows unaffected from these lines. With regard to a preferably simply, robust against dust and vibrations and portable setup only the NIR spectral features are used for civil engineering applications. Most detectors, mainly CCD cameras have rapidly decreasing quantum efficiency in the NIR. Also the quantum efficiency of the photocathode of CCD-Detectors with image intensifier is decreasing in the NIR. Different CCD-detectors were tested with respect to high quantum efficiency and high dynamic range, which is necessary for simultaneous detection of weak spectral lines from trace elements and intense spectral lines from main elements. The measurements are made on reference samples consisting of cement, hydrated cement, cement mortar and concrete with well-defined amounts of the trace elements. Experimental conditions are chosen for an optimum intensity of the trace element spectral lines. The detector systems are compared by limit of detections and the signal to noise ratio. KW - LIBS KW - Sulfur KW - Chlorine KW - NIR KW - Building materials KW - Concrete KW - Detector comparison PY - 2007 DO - https://doi.org/10.1016/j.sab.2007.10.017 SN - 0584-8547 SN - 0038-6987 VL - 62 IS - 12 SP - 1504 EP - 1511 PB - Elsevier CY - Amsterdam AN - OPUS4-16507 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -