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  • 1
    Digitale Medien
    Digitale Medien
    Measuring Permeability of Rigid Materials by a Beam-Bending Method: V, Isotropic Rectangular Plates of Cement Paste (2004)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Ceramic Society 87 (2004), S. 0 
    Details
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: Beam bending is an excellent method for measuring low permeabilities (≤10−18 m2) in homogeneous materials, because it is fast, requires no high pressure, and provides a concurrent measurement of the modulus of the material. The method was previously analyzed and substantiated for cylindrical or square beams. Recently, the analysis was extended to include isotropic and transversely isotropic rectangular beams. In this paper, the analysis is applied to measurements performed on cement paste, and it is shown that the solution for isotropic rectangular beams accounts for changes in the hydrodynamic behavior caused by changing the aspect ratio of the sample. The permeability and elastic modulus results are verified through comparison to previous measurements on cylindrical beams.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1151-2916.2004.tb06342.x
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  • 2
    Digitale Medien
    Digitale Medien
    Thermal Expansion Kinetics: Method to Measure Permeability of Cementitious Materials: I, Theory (2000)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 83 (2000), S. 0 
    Details
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: When a porous material that is saturated with liquid is heated, the liquid typically expands much more than the solid phase; if the permeability is high, then the liquid flows out of the pores as it expands. However, if the permeability is low, then the liquid may not be able to escape, so it expands within the pores and contributes to the dilatation of the body; as the liquid drains from the pores, the body contracts to the dimension dictated by the thermal expansion coefficient of the solid phase. In the low-permeability case, by analyzing the kinetics of dilatation during a change in temperature, it is possible to extract the permeability. This technique, which previously has been successfully applied to gels, is also applicable to conventional ceramics, such as porous glass, sintered ceramics, cement, and concrete. However, for these rigid materials, the analysis must be modified to take account of the finite compressibility of the liquid. In this article, the thermal expansion kinetics are analyzed for cylindrical and platelike samples. The results are applied to cement paste in a companion paper.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1151-2916.2000.tb01627.x
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  • 3
    Digitale Medien
    Digitale Medien
    The Magnesium Electrode in Ether Solution and the Free Energy of Formation of Magnesium Bromide1 (1934)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 56 (1934), S. 18-20 
    Details
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ja01316a005
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  • 4
    Digitale Medien
    Digitale Medien
    Combating the Corrosion Problem with Lubricated Valves (1931)
    s.l. : American Chemical Society
    Industrial & engineering chemistry 23 (1931), S. 986-989 
    Details
    ISSN: 1520-5045
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ie50261a004
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  • 5
    Digitale Medien
    Digitale Medien
    Alloy Steel Valves for Subzero Temperatures (1938)
    s.l. : American Chemical Society
    Industrial & engineering chemistry 30 (1938), S. 1220-1222 
    Details
    ISSN: 1520-5045
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ie50347a005
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  • 6
    Digitale Medien
    Digitale Medien
    Laser fluorescence excitation spectrum of jet-cooled tropolone: The A˜ 1B2–X˜ 1A1 system (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 627-633 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Five of the lowest frequency species a1, b1, and b2 vibrational modes of tropolone in the A˜ 1B2 electronic state are studied using high resolution laser fluorescence excitation spectroscopy of the jet-cooled sample. The ν'26(b1) mode at 38 cm−1, most probably a "folding'' vibration of the seven-membered and O⋅⋅⋅HO chelated ring systems of tropolone, is observed in the progression 26v0 with primarily even valued quantum numbers to v26=14. Tunneling doublets in the progression are observed to decrease from 18.90 cm−1 in the vibrationless state to unresolvable values when v'26 is larger than 8, thereby demonstrating highly mode-specific quenching of the "H atom'' tunneling process by these low frequency, out-of-plane, ring deformation vibrations. The progression 251026v0 is observed to v26=9 and no tunneling doubling is resolved for any of the transitions. These progressions show that the tunneling energy level splitting of tropolone in the vibrationless level of the ground electronic state can be at most about 0.3 cm−1. Additional highly mode-specific interactions with the tunneling process are observed for the in-plane ring deformation modes ν'13(a1) and ν39(b2), but the ν'14(a1) mode at 378.24 cm−1, the lowest frequency a1 mode, is found to interact very little with the tunneling coordinate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.454189
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  • 7
    Digitale Medien
    Digitale Medien
    An unsuspected Fermi perturbation in the acetylene A˜ 1Au 3ν3 level (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 6315-6323 
    Details
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: A previously undetected perturbation in the HCCH A˜ 1Au 3ν3 (trans-bend) level has been found and analyzed. The perturbing level is identified as the A˜ 1Au ν2+2ν4 level. Locally deperturbed molecular constants for the 3ν3 and perturbing level are obtained, along with the perturbation matrix element and the J-dependent mixing coefficients. The A˜-state torsional fundamental, ν4(approximate)850 cm−1, is estimated from the energy of perturbing level. The presence of the perturbation explains large differences between the rotational line intensity patterns observed in the absorption and fluorescence excitation spectra. The perturbed 3ν3 and extra lines are especially prominent in a fluorescence excitation spectrum of the A˜ 1Au–X˜ 1Σ+g 33 0 K10 subband of acetylene rotationally cooled in a supersonic jet.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.451461
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  • 8
    Digitale Medien
    Digitale Medien
    Thermal Expansion Kinetics: Method to Measure Permeability of Cementitious Materials: II, Application to Hardened Cement Pastes (2001)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 84 (2001), S. 0 
    Details
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: A new approach to determine the permeability of cementitious materials is presented in this paper. The method involves the measurement of the thermal dilatation of thin slabs of saturated cement paste. On heating and subsequent isothermal holding, the sample first expands, then gradually contracts over time. The paste is treated as a porous solid with low permeability in which the initial expansion is partly due to the liquid expanding within the pores, putting both solid and liquid under stress. The time-dependent contraction is due to the liquid flowing out of the pores to restore the pressure to equilibrium. By analyzing the kinetics of the thermal expansion and contraction, the liquid permeability of the porous solid can be calculated. The theoretical analysis (presented in a previous paper) is applied to determine the water permeability coefficients of selected cement pastes modified with silica fume and made with different water/solid ratios.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1151-2916.2001.tb00666.x
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  • 9
    Digitale Medien
    Digitale Medien
    Measuring Permeability of Rigid Materials by a Beam-Bending Method: II, Porous Glass (2000)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 83 (2000), S. 0 
    Details
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: It has been shown in a companion paper that the permeability of a porous body can be found from a three-point bending experiment. When the sample is bent, a pressure gradient is created in the liquid within the pores; as the liquid flows in response to the gradient, the force that must be applied to the rod to sustain a fixed deflection decreases with time. By fitting the force decay curve to the predicted shape, the permeability is obtained, along with the elastic modulus. In this paper, that theory is tested using porous Vycor® glass saturated with various solvents, including several normal alcohols, water, and glycerol. The shape of the measured decay is in excellent agreement with the prediction. Consistent with observations of previous workers, we find that the permeability is influenced by the size of the solvent molecule; by assuming that the pore surfaces are covered with a monolayer of immobile solvent, the observed variation can be explained. The advantage of the beam-bending method is that the results are obtained in a few minutes; moreover, there is no problem with leaks or need for high pressures, as there is in conventional measurements of low permeabilities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1151-2916.2000.tb01541.x
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  • 10
    Digitale Medien
    Digitale Medien
    Measuring Permeability of Rigid Materials by a Beam-Bending Method: III, Cement Paste (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    Details
    ISSN: 1551-2916
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau , Physik
    Notizen: The evolution of permeability and elastic modulus for Type III portland cement pastes with water/cement ratios varying from 0.4 to 0.6 were measured using a beam-bending method. Young's modulus was independently verified by measuring the ultrasonic pulse velocity. The permeability ranged over 2 orders of magnitude, depending on the water/cement ratio and the age of the samples. The advantage of the beam-bending method is that the permeability results are obtained in a few minutes to a few hours, whereas conventional techniques take hours or days to measure permeability of this order of magnitude. More importantly, there is no need to maintain high pressure during the measurement period, so leaks are not a problem.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00309.x
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