TY - JOUR A1 - Schlegel, M.C. A1 - Stroh, Julia A1 - Malaga, K. A1 - Meng, Birgit A1 - Panne, Ulrich A1 - Emmerling, Franziska T1 - Pathway of a damaging mechanism - Analyzing chloride attack by synchrotron based X-ray diffraction N2 - Typically, the changes of the phase compositions due to the chemical attack are studied in-situ only by chemical analysis or microscopy. In this study, the chloride transport and binding in the cement matrix in different cementitious materials was analyzed by synchrotron based X-ray diffraction (SyXRD) and energy dispersive X-ray spectroscopy (EDX). Sample materials consisting of cement paste were embedded in high concentrated sodium chloride solution over different time spans. Afterwards, the phase and chemical compositions were determined. The high spatial resolution and the information about the chloride distribution offer a detailed view of chloride binding in the cement matrix and allow the conclusions about the degradation mechanisms. The results are discussed related to the influence of different supplementary cementitious materials on the damaging mechanism. KW - Portland cement KW - In-situ KW - X-Ray diffraction KW - EDX KW - Durability KW - Chloride attack PY - 2015 DO - https://doi.org/10.1016/j.solidstatesciences.2015.03.021 SN - 1293-2558 SN - 1873-3085 VL - 44 SP - 45 EP - 54 PB - Elsevier Masson SAS CY - Amsterdam AN - OPUS4-33171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stroh, Julia A1 - Schlegel, Moritz-Caspar A1 - Schmidt, Wolfram A1 - Nguyen, Thi Yen A1 - Meng, Birgit A1 - Emmerling, Franziska T1 - Time-resolved in situ investigation of Portland cement hydration influenced by chemical admixtures N2 - Numerous admixtures are used in the building practice to customize the properties of the cement paste during application. The influences of admixtures on the course of cement hydration and formation of hydrate phases have to be considered. Polycarboxylate ether (PCE) based polymeric superplasticizers (SPs) are known to retard the setting of the cement paste. The extent of the retardation differs depending on the molecular structure of the SP. Additionally, the presence of a stabilizing agent (SA) in the cement paste has a retarding side effect on the setting. The initial cement hydration processes and the detailed mechanisms of the retardation influenced by PCEs, as well as their interactions with particular SAs, are insufficiently understood. Up to now, only the results of phenomenological studies were taken into account to describe this retardation process. A detailed structure analysis monitoring the change of the phase composition during the hydration was never applied. Both SP and SA affect the adsorption of the sulphate ions on the clinker particles, causing changes in the formation of ettringite during the initial hydration, and are therefore a crucial part of the setting process itself. Here, the initial hydration of cement influenced by the interaction of SP and SA was monitored in situ by synchrotron X-ray diffraction. The high time resolution of the measurements allowed a continuous detection of the hydrates formed. The hydration was followed from the starting point of water addition and for couple of hours afterwards. The hydration of the levitated cement pellets containing starch as SA was initialized by adding aqueous solutions of different commercial SPs. Changes in the ettringite formation were detected in comparison to the reference hydration of pure cement. KW - Synchrotron KW - Portland cement Initial hydration KW - Superplasticizer KW - Stabilizer KW - XRD PY - 2016 DO - https://doi.org/http://dx.doi.org/10.1016/j.conbuildmat.2015.12.097 IS - 106 SP - 18 EP - 26 PB - Elsevier AN - OPUS4-35467 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stroh, Julia A1 - Schlegel, Moritz-Caspar A1 - Irassar, E.F. A1 - Meng, Birgit A1 - Emmerling, Franziska T1 - Applying high resolution SyXRD analysis on sulfate attacked concrete field samples N2 - High resolution synchrotron X-ray diffraction (SyXRD) was applied for a microstructural profile analysis of concrete deterioration after sulfate attack. The cement matrices consist of ordinary Portland cement and different amounts of supplementary cementitious materials, such as fly ash, natural pozzolana and granulated blast furnace slag. The changes of the phase composition were determined along the direction of sulfate ingress. This approach allows the identification of reaction fronts and zones of different phase compositions and conclusions about the mechanisms of sulfate attack. Two reaction fronts were localized in the initial 4 mm from the sample surface. The mechanism of deterioration caused by the exposition in the sulfate-bearing soil is discussed. SyXRD is shown to be a reliable method for investigation of cementitious materials with aggregates embedded in natural environments. KW - X-ray diffraction (B) KW - High resolution KW - Degradation (C) KW - Sulfate attack (C) KW - Concrete (E) PY - 2014 DO - https://doi.org/10.1016/j.cemconres.2014.07.015 SN - 0008-8846 SN - 1873-3948 VL - 66 SP - 19 EP - 26 PB - Pergamon Press CY - New York, NY AN - OPUS4-31253 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stroh, Julia T1 - Investigations of Degradation of Cementitious Materials by in-situ Structure Analysis T2 - Adlershofer Forschungsforum CY - Berlin, Germany DA - 2013-11-12 PY - 2013 AN - OPUS4-29828 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Surov, Artem O. A1 - Vasilev, Nikita A. A1 - Churakov, Andrei V. A1 - Stroh, Julia A1 - Emmerling, Franziska A1 - Perlovich, German L. T1 - Solid Forms of Ciprofloxacin Salicylate: Polymorphism, Formation Pathways, and Thermodynamic Stability N2 - The crystallization of ciprofloxacin - an antibacterial fluoroquinolone compound - with salicylic acid resulted in the isolation of five distinct solid forms of the drug, namely, an anhydrous salt, two polymorphic forms of the salt monohydrate, methanol and acetonitrile solvates, and the salt-cocrystal hydrate. The salicylate salts were investigated by different analytical techniques ranging from powder and single crystal X-ray diffractometry, differential scanning calorimetry, thermogravimetric analysis, variable temperature powder X-ray diffraction, dynamic vapor sorption analysis, dissolution, and solubility investigations. Real-time in situ Raman spectroscopy was used to investigate the mechanochemical formation pathways of the different solid polymorphs of ciprofloxacin salicylate. The mechanism of the phase transformation between the crystalline forms was evaluated under mechanochemical conditions. It was found that the formation pathway and kinetics of the grinding process depend on the form of the starting material and reaction conditions. The analysis of the solid-state thermal evolution of the hydrated salts revealed the two-step mechanism of dehydration process, which proceeds through a formation of the distinct intermediate crystalline products. KW - Cocrystal KW - Polymorphism KW - Ciprofloxacin KW - XRD KW - DSC PY - 2019 DO - https://doi.org/10.1021/acs.cgd.9b00185 SN - 1528-7483 VL - 19 IS - 5 SP - 2979 EP - 2990 PB - American Chemical Society AN - OPUS4-47903 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stroh, Julia T1 - High resolution in situ monitoring of the initial cement hydration influenced by organic admixtures N2 - Numerous admixtures are used in the building practice to customize the properties of the cement paste during application. The influences of admixtures on the course of cement hydration and formation of hydrate phases have to be considered. Polycarboxylate ether (PCE) based polymeric superplasticizers (SPs) are known to retard the setting of the cement paste. The extent of the retardation differs depending on the molecular structure of the SP. Additionally, the presence of a stabilizing agent (SA) in the cement paste has a retarding side effect on the setting. The initial cement hydration processes and the detailed mechanisms of the retardation influenced by PCEs, as well as their interactions with particular SAs, are insufficiently understood. Up to now, only the results of phenomenological studies were taken into account to describe this retardation process. A detailed structure analysis monitoring the change of the phase composition during the hydration was never applied. Both SP and SA affect the adsorption of the sulphate ions on the clinker particles, causing changes in the formation of ettringite during the initial hydration, and are therefore a crucial part of the setting process itself. Here, the initial hydration of cement influenced by the interaction of SP and SA was monitored in situ by synchrotron X-ray diffraction. The high time resolution of the measurements allowed a continuous detection of the hydrates formed. The hydration was followed from the starting point of water addition and for couple of hours afterwards. The hydration of the levitated cement pellets containing starch as SA was initialized by adding aqueous solutions of different commercial SPs. Changes in the ettringite formation were detected in comparison to the reference hydration of pure cement. T2 - Early Age Concrete: From the Research Lab to the Construction Site CY - Tomsk, Russia DA - 02.06.2015 KW - Portland cement KW - Initial hydration KW - Superplasticizer KW - Stabilizer KW - Synchrotron XRD PY - 2015 AN - OPUS4-35470 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -