TY - JOUR A1 - Fernandez-Menendez, L. J. A1 - Mendez-Lopez, C. A1 - Abad Andrade, Carlos Enrique A1 - Fandino, J. A1 - Gonzalez-Gago, C. A1 - Pisonero, J. A1 - Bordel, N. T1 - A critical evaluation of the chlorine quantification method based on molecular emission detection in LIBS JF - Spectrochimica Acta Part B: Atomic Spectroscopy N2 - The entire process involving the determination of Cl by molecular emission detection in Laser-Induced Breakdown Spectroscopy (LIBS) is thoroughly studied in this paper. This critical evaluation considers how spectra are normalized, how interferences from other molecular species signals are removed, and how signal integration is applied. Moreover, a data treatment protocol is proposed to achieve reliable and accurate Cl determination from the CaCl molecular spectral signal, not requiring the use of more complex numerical approaches. Calcium chloride dihydrate (CaCl2⋅2H2O) and high purity anhydrite samples (CaSO4) are used to optimize the acquisition conditions and data treatment of CaCl emission signal. Using the developed protocol, calibration curves for Cl, covering the concentration range from 0 μg/g to 60,000 μg/g of Cl, are successfully achieved. Finally, the suitability of the proposed methodology for Cl determination is successfully applied in industrial gypsum waste samples, where the results obtained by LIBS are validated using high-resolution molecular absorption spectroscopy (HR-CS-MAS) and potentiometric titration. KW - Laser induced breakdown Spectrocopy (LIBS) KW - Molecular spectra KW - Chlorine determination KW - CaCl emission bands KW - Industrial gypsum PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-544292 DO - https://doi.org/10.1016/j.sab.2022.106390 SN - 0584-8547 VL - 190 SP - 1 EP - 9 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-54429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Andrade, C. A1 - Saucedo, L. A1 - Rebolledo, N. A1 - Cabeza, S. A1 - Meinel, Dietmar T1 - X-Ray computed tomography and traditional analysis of a capillary absorption test in cement pastes JF - Cement and Concrete Composites N2 - Water absorption testing has the attraction of being simple, relatively quick and use water as a fluid which is the key substance in the possible concrete deterioration. However, in spite of the advantages its application has remained empirical, except for the testing of resistance to frost, through the identification of the critical degree of saturation. Rilem TC-116 studied this test, among others, for the characterization of concrete resistance against transport through the concrete pore network. Results indicated a low discriminating ability of the absorbency for qualifying concrete resistance and then, it seemed necessary to try to move forward by making the link between the absorption testing and the concrete pore microstructure. In the present work, thanks to the X-Ray computed tomography, it is described the evolution of the water front in three paste-specimen with different w/c ratios (different pore radius distributions). The observations allowed us to deduce that all the pores start to fill simultaneously, but the bigger ones fill quicker and rise less. The saturation degree is measured along the height of the sample, showing that each pore size has a different rate which becomes constant after the first hour. Washburn’s equation was applied to the progressive advance of the water front, resulting in a pore radius much smaller than the one expected. KW - Capillary absorption KW - Pore size distribution KW - X-ray CT KW - Gravimetry PY - 2020 DO - https://doi.org/10.1016/j.cemconcomp.2020.103634 VL - 113 SP - 103634 PB - Elsevier Ltd. CY - London AN - OPUS4-51487 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Matos, P. R. de A1 - Andrade Neto, J. S. A1 - Durlo Tambara, Luis Urbano A1 - Rodríguez, E. D. A1 - Kirchheim, A. P. A1 - Campos, C. E. M. de T1 - Measuring the early-age volumetric change of cement paste through in-situ XRD JF - Materials Today Communications N2 - Volumetric changes follow Portland cement hydration reactions: aluminates' hydration is generally expansive, whereas silicates' reaction leads to shrinkage. Determining the volumetric variation at very early ages (i.e., first minutes/hours) presents operational challenges; most standards prescribe the measurement on specimens that are already hardened, while measurements from the fresh state are not standardized. This article reports the first attempt to use in-situ X-ray diffraction (XRD) to measure the early-age volumetric variation of a cementitious paste. For this purpose, a C3A + gypsum paste was assessed for 36 h, measuring its vertical displacement over time through XRD. The results showed that the expansion increased in the first ∼13 h, in line with the ettringite formed up to ∼11 h. In addition, the volumetric expansion agreed well with the heat release in calorimetry. It is concluded that the volumetric variation measurement of cementitious pastes through in-situ XRD is a promising technique, but further studies are needed to make this technique consolidated. KW - X-ray diffraction KW - Shrinkage KW - Expansion KW - Hydration KW - Portland cement PY - 2023 DO - https://doi.org/10.1016/j.mtcomm.2023.106857 SN - 2352-4928 VL - 36 SP - 1 EP - 4 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-58107 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stindt, Arne A1 - Andrade, M. A. B. A1 - Buurman, Merwe A1 - Adamowski, J. C. A1 - Panne, Ulrich A1 - Riedel, Jens T1 - Experimental and numerical characterization of the sound pressure in standing wave acoustic levitators JF - Review of scientific instruments N2 - A novel method for predictions of the sound pressure distribution in acoustic levitators is based on a matrix representation of the Rayleigh integral. This method allows for a fast calculation of the acoustic field within the resonator. To make sure that the underlying assumptions and simplifications are justified, this approach was tested by a direct comparison to experimental data. The experimental sound pressure distributions were recorded by high spatially resolved frequency selective microphone scanning. To emphasize the general applicability of the two approaches, the comparative studies were conducted for four different resonator geometries. In all cases, the results show an excellent agreement, demonstrating the accuracy of the matrix method. KW - Acoustic levitation KW - Matrix calculation KW - Microphony KW - Noncontact ultrasonic transportation KW - Small objects KW - Matrix-method KW - Droplets KW - Air KW - Manipulation KW - Simulation KW - Fields KW - Water PY - 2014 DO - https://doi.org/10.1063/1.4861197 SN - 0034-6748 SN - 1089-7623 N1 - Geburtsname von Buurman, Merwe: Albrecht, M. - Birth name of Buurman, Merwe: Albrecht, M. VL - 85 IS - 015110 SP - 1 EP - 6 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-30405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Andrade, M. A. B. A1 - Stindt, Arne A1 - Panne, Ulrich A1 - Riedel, Jens A1 - Adamowski, J. C. T1 - Numerical and experimental determination of the sound pressure distribution in single-axis acoustic levitators T2 - IUS 2012 - IEEE International Ultrasonics Symposium (Proceedings) N2 - This paper presents a numerical and an experimental procedure to obtain the pressure field in single-axis acoustic levitators. Numerically, the pressure field is determined by a matrix method based on the Rayleigh integral that take into account the multiple wave reflections that occur between the transducer and the reflector. The numerical pressure field is compared with the acoustic pressure measured by an earplug microphone, that is connected to a hollow needle. The tip of the needle is moved by a µm translation stage through the field and the signal is recorded using a lock-in amplifier locked to the levitator frequency. The pressure field obtained numerically show good agreement with that obtained experimentally. T2 - 2012 IEEE International Ultrasonics Symposium (IUS) CY - Dresden, Germany DA - 2012-10-07 KW - Acoustic levitation KW - Matrix method KW - Pressure field PY - 2012 SN - 978-1-4673-4562-0 DO - https://doi.org/10.1109/ULTSYM.2012.0690 SN - 1948-5719 SP - 2754 EP - 2757 AN - OPUS4-32587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -