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Lucie Vandewalle - One of the best experts on this subject based on the ideXlab platform.
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Round-robin analysis of the RILEM TC 162-TDF Beam-Bending test: Part 1 - Test method evaluation
Materials and Structures, 2003Co-Authors: B. I. G. Barr, M. K. Lee, E. J. De Place Hansen, D. Dupont, E. Erdem, S. Schaerlaekens, B. Schnütgen, Henrik Stang, Lucie VandewalleAbstract:A round robin test programme was carried out on the Beam-Bending test recommended by the RILEM TC 162-TDF [1]. Plain concrete and steel fibre reinforced concrete (SFRC) Beams were included in the test programme. The material variables for the SFRC Beams consisted of two concrete strengths, three fibre dosages and three types of fibres. A comprehensive statistical analysis was carried out to determine the applicability and robustness of the test method. It was found that although inter-lab variations do occur, this was relatively small compared to the inherent material variation. It is also possible that the high variations observed could be due to the relatively small cross sections used for the test Beams. Additionally, an investigation was carried out to evaluate the objectiveness of the calculation procedure proposed by RILEM TC 162-TDF to obtain the necessary design parameters. It was found that the prescribed calculation procedure was satisfactory, as the variation between the design parameters calculated at different laboratories was generally within the range of ±5%. An alternative method of obtaining the design parameters, by considering residual strengths, is suggested as it simplifies the calculation procedure and the test method. In general, the Beam test was found to be a good robust test and relatively easy to carry out.
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Round-robin analysis of the RILEM TC 162-TDF Beam-Bending test: Part 2—Approximation of δ from the CMOD response
Materials and Structures, 2003Co-Authors: B. I. G. Barr, E. J. De Place Hansen, D. Dupont, E. Erdem, S. Schaerlaekens, B. Schnütgen, Henrik Stang, M. M. Lee, Lucie VandewalleAbstract:A round robin test programme was carried out using the Beam-Bending test recommended by RILEM TC 162-TDF [1]. The test programme included both plain and steel fibre reinforced concrete (SFRC) Beams. A detailed analysis was carried out to investigate the influence of different test configurations on measurements of the crack mouth opening displacement (CMOD). Linear elastic fracture mechanics (LEFM) and non-linear fracture mechanics (NLFM) methods were utilised to investigate the problem analytically. From the analytical studies carried out, it is proposed that the CMOD should not be measured at a distance more than 5mm from the bottom fibre of the Beam. A larger distance than 5mm will cause the deviation between the measured CMOD and the true CMOD to reach an unacceptable level. A simple rigid body model has been proposed to relate the CMOD to the mid-span deflection. The NLFM analysis and experimental results were compared for both the plain and SFRC Beam results and it was found that results based on the basis of CMOD can be compared to those based on deflections, for practical purposes, using the simple rigid body model. The experimental results strongly suggest that the rigid body model could be effectively applied for all the types of materials tested in the round robin test programme. In addition it was found that the conversion from CMOD to the equivalent mid-span deflection, δc, revealed good agreement between the load-average mid-span deflection (P-δ) curve and the load-equivalent mid-span deflection (P-δ) curve especially for the SFRC specimens. It is proposed that the load-CMOD (P-CMOD) curve be used to calculate the proposed RILEM design parameters (as opposed to the P-δ curve) via the use of a correction factor determined using the simple rigid body model.
Manuel Lopez-amo - One of the best experts on this subject based on the ideXlab platform.
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Concrete Beam Bending Test Monitorization Using a High Strain Fiber Optic Sensor
Journal of Lightwave Technology, 2012Co-Authors: Mikel Bravo, M Bravo-Navas, Julia Saenz, Manuel Lopez-amoAbstract:In this work the development of an "eight-shape" fiber optic sensor for high strain measurement is experimentally demonstrated. This strain sensor is interrogated using a commercial optical time domain reflectometer through a dual configuration that is able to measure backscattering and the transmission of an intensity pulse while reducing unwanted cladding-mode coupling effects. An 'in field' concrete Beam Bending test was also performed in order to compare the proposed intensity Bending sensor with the mature fiber Bragg grating technology.
George W. Scherer - One of the best experts on this subject based on the ideXlab platform.
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Permeability of shale by the Beam-Bending method
International Journal of Rock Mechanics and Mining Sciences, 2012Co-Authors: Jie Zhang, George W. SchererAbstract:Abstract The Beam-Bending method permits measurement of liquid permeability in the nanoDarcy range in a few minutes to a few hours. This technique has been applied successfully to determine the permeability, as well as the viscoelastic properties, of isotropic materials with low permeability, such as gels, porous glass, and cement paste. The method has been extended to measure transversely anisotropic materials, such as sedimentary rock, to find the permeability parallel and perpendicular to the bedding. In this study, measurements have been made on a set of shales from varying depths and locations in the continental United States. The measured permeabilities range 0.009–400 nanoDarcies (nD=10 −21 m 2 ). The permeability in the direction parallel to the bedding orientation was larger than that perpendicular to the bedding orientation, by a factor ranging from 1.2 to 6. This is the first instance of using the Beam-Bending method to measure the permeabilities of shale in different orientations. The measured permeabilities were compared to the Kozeny–Carman and Katz–Thompson models. The pore geometry parameters used in the models, such as the pore size distribution, characteristic pore diameters, porosity, and tortuosity were measured using mercury intrusion porosimetry (MIP), gravimetry, and electrical conductivity, respectively. The measured permeability values match better with the predictions from the Katz–Thompson equation.
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Measuring Permeability of Rigid Materials by a Beam‐Bending Method: V, Isotropic Rectangular Plates of Cement Paste
Journal of the American Ceramic Society, 2005Co-Authors: John J. Valenza, George W. SchererAbstract: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.
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Measuring Permeability of Rigid Materials by a Beam-Bending Method: II, Porous Glass
Journal of the American Ceramic Society, 2004Co-Authors: Wilasa Vichit-vadakan, George W. SchererAbstract: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.
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Measuring permeability of rigid materials by a Beam-Bending method: IV, transversely isotropic plate
Journal of the American Ceramic Society, 2004Co-Authors: George W. SchererAbstract:A simple Beam-Bending measurement can be used to determine the permeability, as well as the modulus, of a saturated porous material. The procedure is to apply a constant deflection and measure the load decay as the pressure in the pores equilibrates; alternatively, an oscillatory deflection can be applied and the phase delay measured. The analysis of the experiment has been previously presented for Beams with square or round cross sections. In this article, we consider the case of a saturated porous Beam with a rectangular cross section and transverse isotropy; that is, the permeability and elastic properties are uniform in the x 1 -x 2 plane, but have different values in the x 3 direction. This is the case for a sedimentary stone or laminated composite, for example. The kinetics of hydrodynamic relaxation depend on the orientation of the planes with respect to the Bending axis; consequently, three different solutions are presented that allow determination of the properties in each direction. Exact solutions are obtained for elastic Beams; an approximation for the case of a viscoelastic anisotropic Beam also is presented. The relaxation kinetics of an isotropic rectangular plate are obtained as a special case; that geometry is convenient to use for isotropic materials, such as cement paste or mortar.
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measuring permeability of rigid materials by a Beam Bending method iii cement paste
Journal of the American Ceramic Society, 2002Co-Authors: Wilasa Vichitvadakan, George W. SchererAbstract: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.
B. I. G. Barr - One of the best experts on this subject based on the ideXlab platform.
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Round-robin analysis of the RILEM TC 162-TDF Beam-Bending test: Part 1 - Test method evaluation
Materials and Structures, 2003Co-Authors: B. I. G. Barr, M. K. Lee, E. J. De Place Hansen, D. Dupont, E. Erdem, S. Schaerlaekens, B. Schnütgen, Henrik Stang, Lucie VandewalleAbstract:A round robin test programme was carried out on the Beam-Bending test recommended by the RILEM TC 162-TDF [1]. Plain concrete and steel fibre reinforced concrete (SFRC) Beams were included in the test programme. The material variables for the SFRC Beams consisted of two concrete strengths, three fibre dosages and three types of fibres. A comprehensive statistical analysis was carried out to determine the applicability and robustness of the test method. It was found that although inter-lab variations do occur, this was relatively small compared to the inherent material variation. It is also possible that the high variations observed could be due to the relatively small cross sections used for the test Beams. Additionally, an investigation was carried out to evaluate the objectiveness of the calculation procedure proposed by RILEM TC 162-TDF to obtain the necessary design parameters. It was found that the prescribed calculation procedure was satisfactory, as the variation between the design parameters calculated at different laboratories was generally within the range of ±5%. An alternative method of obtaining the design parameters, by considering residual strengths, is suggested as it simplifies the calculation procedure and the test method. In general, the Beam test was found to be a good robust test and relatively easy to carry out.
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Round-robin analysis of the RILEM TC 162-TDF Beam-Bending test: Part 2—Approximation of δ from the CMOD response
Materials and Structures, 2003Co-Authors: B. I. G. Barr, E. J. De Place Hansen, D. Dupont, E. Erdem, S. Schaerlaekens, B. Schnütgen, Henrik Stang, M. M. Lee, Lucie VandewalleAbstract:A round robin test programme was carried out using the Beam-Bending test recommended by RILEM TC 162-TDF [1]. The test programme included both plain and steel fibre reinforced concrete (SFRC) Beams. A detailed analysis was carried out to investigate the influence of different test configurations on measurements of the crack mouth opening displacement (CMOD). Linear elastic fracture mechanics (LEFM) and non-linear fracture mechanics (NLFM) methods were utilised to investigate the problem analytically. From the analytical studies carried out, it is proposed that the CMOD should not be measured at a distance more than 5mm from the bottom fibre of the Beam. A larger distance than 5mm will cause the deviation between the measured CMOD and the true CMOD to reach an unacceptable level. A simple rigid body model has been proposed to relate the CMOD to the mid-span deflection. The NLFM analysis and experimental results were compared for both the plain and SFRC Beam results and it was found that results based on the basis of CMOD can be compared to those based on deflections, for practical purposes, using the simple rigid body model. The experimental results strongly suggest that the rigid body model could be effectively applied for all the types of materials tested in the round robin test programme. In addition it was found that the conversion from CMOD to the equivalent mid-span deflection, δc, revealed good agreement between the load-average mid-span deflection (P-δ) curve and the load-equivalent mid-span deflection (P-δ) curve especially for the SFRC specimens. It is proposed that the load-CMOD (P-CMOD) curve be used to calculate the proposed RILEM design parameters (as opposed to the P-δ curve) via the use of a correction factor determined using the simple rigid body model.
Mikel Bravo - One of the best experts on this subject based on the ideXlab platform.
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Concrete Beam Bending Test Monitorization Using a High Strain Fiber Optic Sensor
Journal of Lightwave Technology, 2012Co-Authors: Mikel Bravo, M Bravo-Navas, Julia Saenz, Manuel Lopez-amoAbstract:In this work the development of an "eight-shape" fiber optic sensor for high strain measurement is experimentally demonstrated. This strain sensor is interrogated using a commercial optical time domain reflectometer through a dual configuration that is able to measure backscattering and the transmission of an intensity pulse while reducing unwanted cladding-mode coupling effects. An 'in field' concrete Beam Bending test was also performed in order to compare the proposed intensity Bending sensor with the mature fiber Bragg grating technology.