TY - CONF A1 - Wilsch, Gerd A1 - Gottlieb, Cassian A1 - Günther, Tobias A1 - Millar, Steven T1 - Fast quantitave chemical analysis of concrete using LIBS N2 - Overview about LIBS applications for investigation of building materials. T2 - NDT&E Advanced Training Workshop CY - Berlin, Germany DA - 27.06.2018 KW - LIBS KW - Concrete KW - Damage processes KW - Chlorid KW - Sulfate KW - Alkalies PY - 2018 AN - OPUS4-46821 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wilsch, Gerd A1 - Gottlieb, Cassian A1 - Günther, Tobias A1 - Millar, Steven A1 - Völker, Tobias T1 - Application of LIBS for the chemical investigation of concrete infrastructure N2 - The majority of the built infrastructure is made of concrete, which is a multiphase system made of cement, aggregates, water and pores. Concrete is often used in combination with steel as reinforced concrete. Environmental influences, especially the ingress of harmful ions in combination with the ingress of water, trigger different damage processes which reduce the designed lifetime of a structure. The ingress of chlorides from de-icing salt or sea water leads to corrosion of the reinforcement. Also the carbonation of the concrete may trigger the corrosion of the reinforcement. The ingress of alkalis from de-icing salts may cause the expansion of the amorphous silica aggregates (alkali-silica reaction) through formation of a swelling gel of calcium silicate hydrate if water is present. The ingress of sulfates may cause spalling of the concrete surface due to ettringite formation. For the standard procedure in civil engineering cores are taken, cut in slices, grinded and the obtained homogenized powder is solved in acid and investigated by standard procedures. BAM has developed the LIBS technique for the 2D evaluation of the chemical composition of concrete [1-11]. The technique is established for automated laboratory use with high numbers of samples to investigate transport processes of harmful species (Cl-, CO2, SO42- and alkalis) in concrete. Information about ingress depth and the quantitative values are important to estimate the remaining lifetime of the infrastructure. LIBS is a surface technique. To get information about the ingress depth, a core has to be taken and cut in the middle. The measurements are carried out at the cross section. The main advantages of LIBS are the direct measurement on the surface of the concrete, fast analysis (sample rate 100 Hz) with a spatial resolution of up to 100 µm, the consideration of the heterogeneity of the concrete and the possibility of automated measurements which save a lot of manpower and time. As an example the investigation of ingress profiles for standard diffusion and migration tests in civil engineering takes hours in comparison to just a few minutes using LIBS. At the same time a 2D-evaluation provides information about hot spots of elemental concentration which may not be found by standard methods. Ingress of chlorides due to a crack in a repair mortar. Left: Photo of the cross section of a concrete core and the surface investigated by LIBS (area 70 mm x 70 mm). Right: Color coded chlorine intensity on the cross section of a concrete core, dark red represents high chlorine content. The state of the art of LIBS technique for applications in civil engineering will be presented, including typical results of 2D investigation of concrete in laboratory. The performance is also demonstrated by examples for onsite applications using a mobile LIBS system. The road map to standardization is presented as well. T2 - ICCRRR2018, 5th international conference on Concrete Repair, Rehabilitation and Retrofitting CY - Cape Town, South Africa DA - 19.11.2018 KW - LIBS KW - Chlorid KW - Alkalies KW - Concrete KW - Damage PY - 2018 AN - OPUS4-46781 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -