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Benoit Masson - One of the best experts on this subject based on the ideXlab platform.

  • Addendum to 'Is long-term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self-desiccation?'
    Cement and Concrete Research, 2019
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Prof. F.-J. Ulm brought to our attention that we forgot to include an important reference in our manuscript. Indeed, Ulm et al. [1] showed that, for 5 concretes that differed in their water-to-cement ratio and for which basic Creep and autogenous shrinkage were measured by Le Roy [2], the long-term kinetics of autogenous shrinkage could be explained by Creep of the solid skeleton under the action of an internal pore pressure. Their conclusion was based on the observed linearity of the relationship between basic Creep compliance and increase in autogenous shrinkage in the long term. From the slope of this linear relationship, they back-calculated an “effective pore pressure” displayed in Fig. 1. Interestingly, this uniaxial “effective pore pressure” – merely calculated from macroscopic observables – is in very good agreement (both in terms of magnitude and in terms of trend with water-to-cement ratio) with the capillary stresses that we estimated at the pore scale with the help of micromechanics (see Fig. 6 in our manuscript). The reason for this agreement lies in Eq. 16 of our manuscript, which reads Σ∞ = σ∞ and shows that, in the linear viscoelastic case with a viscoelastic Poisson's ratio of the matrix equal to 0.2, the long-term “effective” macroscopic stress Σ∞ that acts at the scale of the concrete sample is equal to the long-term microscopic stress σ∞ that acts on the C-S-H gel.

  • addendum to is long term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self desiccation
    Cement and Concrete Research, 2019
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Prof. F.-J. Ulm brought to our attention that we forgot to include an important reference in our manuscript. Indeed, Ulm et al. [1] showed that, for 5 concretes that differed in their water-to-cement ratio and for which basic Creep and autogenous shrinkage were measured by Le Roy [2], the long-term kinetics of autogenous shrinkage could be explained by Creep of the solid skeleton under the action of an internal pore pressure. Their conclusion was based on the observed linearity of the relationship between basic Creep compliance and increase in autogenous shrinkage in the long term. From the slope of this linear relationship, they back-calculated an “effective pore pressure” displayed in Fig. 1. Interestingly, this uniaxial “effective pore pressure” – merely calculated from macroscopic observables – is in very good agreement (both in terms of magnitude and in terms of trend with water-to-cement ratio) with the capillary stresses that we estimated at the pore scale with the help of micromechanics (see Fig. 6 in our manuscript). The reason for this agreement lies in Eq. 16 of our manuscript, which reads Σ∞ = σ∞ and shows that, in the linear viscoelastic case with a viscoelastic Poisson's ratio of the matrix equal to 0.2, the long-term “effective” macroscopic stress Σ∞ that acts at the scale of the concrete sample is equal to the long-term microscopic stress σ∞ that acts on the C-S-H gel.

  • Is long-term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self-desiccation?
    Cement and Concrete Research, 2018
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Long-term shrinkage and Creep of concrete can impact the lifetime of concrete structures. Basic Creep of cementitious materials is now known to be non-asymptotic and evolve logarithmically with time at large times. However, the long-term kinetics of autogenous shrinkage is not systematically analyzed. Here we first aim at finding out how autogenous shrinkage evolves with time at long term. We analyze all experimental data available in the literature and find that autogenous shrinkage evolves logarithmically with respect to time at long term, like basic Creep. Then, by considering concrete as a multiscale material, we obtain the bulk Creep modulus of the calcium silicate hydrate gel. In the end, we show that the kinetics of long-term autogenous shrinkage can be a viscoelastic response to self-desiccation by comparing the mechanical stress that should be applied to explain this long-term kinetics of autogenous shrinkage with the capillary force due to self-desiccation.

Abudushalamu Aili - One of the best experts on this subject based on the ideXlab platform.

  • Addendum to 'Is long-term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self-desiccation?'
    Cement and Concrete Research, 2019
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Prof. F.-J. Ulm brought to our attention that we forgot to include an important reference in our manuscript. Indeed, Ulm et al. [1] showed that, for 5 concretes that differed in their water-to-cement ratio and for which basic Creep and autogenous shrinkage were measured by Le Roy [2], the long-term kinetics of autogenous shrinkage could be explained by Creep of the solid skeleton under the action of an internal pore pressure. Their conclusion was based on the observed linearity of the relationship between basic Creep compliance and increase in autogenous shrinkage in the long term. From the slope of this linear relationship, they back-calculated an “effective pore pressure” displayed in Fig. 1. Interestingly, this uniaxial “effective pore pressure” – merely calculated from macroscopic observables – is in very good agreement (both in terms of magnitude and in terms of trend with water-to-cement ratio) with the capillary stresses that we estimated at the pore scale with the help of micromechanics (see Fig. 6 in our manuscript). The reason for this agreement lies in Eq. 16 of our manuscript, which reads Σ∞ = σ∞ and shows that, in the linear viscoelastic case with a viscoelastic Poisson's ratio of the matrix equal to 0.2, the long-term “effective” macroscopic stress Σ∞ that acts at the scale of the concrete sample is equal to the long-term microscopic stress σ∞ that acts on the C-S-H gel.

  • addendum to is long term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self desiccation
    Cement and Concrete Research, 2019
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Prof. F.-J. Ulm brought to our attention that we forgot to include an important reference in our manuscript. Indeed, Ulm et al. [1] showed that, for 5 concretes that differed in their water-to-cement ratio and for which basic Creep and autogenous shrinkage were measured by Le Roy [2], the long-term kinetics of autogenous shrinkage could be explained by Creep of the solid skeleton under the action of an internal pore pressure. Their conclusion was based on the observed linearity of the relationship between basic Creep compliance and increase in autogenous shrinkage in the long term. From the slope of this linear relationship, they back-calculated an “effective pore pressure” displayed in Fig. 1. Interestingly, this uniaxial “effective pore pressure” – merely calculated from macroscopic observables – is in very good agreement (both in terms of magnitude and in terms of trend with water-to-cement ratio) with the capillary stresses that we estimated at the pore scale with the help of micromechanics (see Fig. 6 in our manuscript). The reason for this agreement lies in Eq. 16 of our manuscript, which reads Σ∞ = σ∞ and shows that, in the linear viscoelastic case with a viscoelastic Poisson's ratio of the matrix equal to 0.2, the long-term “effective” macroscopic stress Σ∞ that acts at the scale of the concrete sample is equal to the long-term microscopic stress σ∞ that acts on the C-S-H gel.

  • Is long-term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self-desiccation?
    Cement and Concrete Research, 2018
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Long-term shrinkage and Creep of concrete can impact the lifetime of concrete structures. Basic Creep of cementitious materials is now known to be non-asymptotic and evolve logarithmically with time at large times. However, the long-term kinetics of autogenous shrinkage is not systematically analyzed. Here we first aim at finding out how autogenous shrinkage evolves with time at long term. We analyze all experimental data available in the literature and find that autogenous shrinkage evolves logarithmically with respect to time at long term, like basic Creep. Then, by considering concrete as a multiscale material, we obtain the bulk Creep modulus of the calcium silicate hydrate gel. In the end, we show that the kinetics of long-term autogenous shrinkage can be a viscoelastic response to self-desiccation by comparing the mechanical stress that should be applied to explain this long-term kinetics of autogenous shrinkage with the capillary force due to self-desiccation.

Jean Michel Torrenti - One of the best experts on this subject based on the ideXlab platform.

  • Addendum to 'Is long-term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self-desiccation?'
    Cement and Concrete Research, 2019
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Prof. F.-J. Ulm brought to our attention that we forgot to include an important reference in our manuscript. Indeed, Ulm et al. [1] showed that, for 5 concretes that differed in their water-to-cement ratio and for which basic Creep and autogenous shrinkage were measured by Le Roy [2], the long-term kinetics of autogenous shrinkage could be explained by Creep of the solid skeleton under the action of an internal pore pressure. Their conclusion was based on the observed linearity of the relationship between basic Creep compliance and increase in autogenous shrinkage in the long term. From the slope of this linear relationship, they back-calculated an “effective pore pressure” displayed in Fig. 1. Interestingly, this uniaxial “effective pore pressure” – merely calculated from macroscopic observables – is in very good agreement (both in terms of magnitude and in terms of trend with water-to-cement ratio) with the capillary stresses that we estimated at the pore scale with the help of micromechanics (see Fig. 6 in our manuscript). The reason for this agreement lies in Eq. 16 of our manuscript, which reads Σ∞ = σ∞ and shows that, in the linear viscoelastic case with a viscoelastic Poisson's ratio of the matrix equal to 0.2, the long-term “effective” macroscopic stress Σ∞ that acts at the scale of the concrete sample is equal to the long-term microscopic stress σ∞ that acts on the C-S-H gel.

  • addendum to is long term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self desiccation
    Cement and Concrete Research, 2019
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Prof. F.-J. Ulm brought to our attention that we forgot to include an important reference in our manuscript. Indeed, Ulm et al. [1] showed that, for 5 concretes that differed in their water-to-cement ratio and for which basic Creep and autogenous shrinkage were measured by Le Roy [2], the long-term kinetics of autogenous shrinkage could be explained by Creep of the solid skeleton under the action of an internal pore pressure. Their conclusion was based on the observed linearity of the relationship between basic Creep compliance and increase in autogenous shrinkage in the long term. From the slope of this linear relationship, they back-calculated an “effective pore pressure” displayed in Fig. 1. Interestingly, this uniaxial “effective pore pressure” – merely calculated from macroscopic observables – is in very good agreement (both in terms of magnitude and in terms of trend with water-to-cement ratio) with the capillary stresses that we estimated at the pore scale with the help of micromechanics (see Fig. 6 in our manuscript). The reason for this agreement lies in Eq. 16 of our manuscript, which reads Σ∞ = σ∞ and shows that, in the linear viscoelastic case with a viscoelastic Poisson's ratio of the matrix equal to 0.2, the long-term “effective” macroscopic stress Σ∞ that acts at the scale of the concrete sample is equal to the long-term microscopic stress σ∞ that acts on the C-S-H gel.

  • Is long-term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self-desiccation?
    Cement and Concrete Research, 2018
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Long-term shrinkage and Creep of concrete can impact the lifetime of concrete structures. Basic Creep of cementitious materials is now known to be non-asymptotic and evolve logarithmically with time at large times. However, the long-term kinetics of autogenous shrinkage is not systematically analyzed. Here we first aim at finding out how autogenous shrinkage evolves with time at long term. We analyze all experimental data available in the literature and find that autogenous shrinkage evolves logarithmically with respect to time at long term, like basic Creep. Then, by considering concrete as a multiscale material, we obtain the bulk Creep modulus of the calcium silicate hydrate gel. In the end, we show that the kinetics of long-term autogenous shrinkage can be a viscoelastic response to self-desiccation by comparing the mechanical stress that should be applied to explain this long-term kinetics of autogenous shrinkage with the capillary force due to self-desiccation.

Matthieu Vandamme - One of the best experts on this subject based on the ideXlab platform.

  • Addendum to 'Is long-term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self-desiccation?'
    Cement and Concrete Research, 2019
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Prof. F.-J. Ulm brought to our attention that we forgot to include an important reference in our manuscript. Indeed, Ulm et al. [1] showed that, for 5 concretes that differed in their water-to-cement ratio and for which basic Creep and autogenous shrinkage were measured by Le Roy [2], the long-term kinetics of autogenous shrinkage could be explained by Creep of the solid skeleton under the action of an internal pore pressure. Their conclusion was based on the observed linearity of the relationship between basic Creep compliance and increase in autogenous shrinkage in the long term. From the slope of this linear relationship, they back-calculated an “effective pore pressure” displayed in Fig. 1. Interestingly, this uniaxial “effective pore pressure” – merely calculated from macroscopic observables – is in very good agreement (both in terms of magnitude and in terms of trend with water-to-cement ratio) with the capillary stresses that we estimated at the pore scale with the help of micromechanics (see Fig. 6 in our manuscript). The reason for this agreement lies in Eq. 16 of our manuscript, which reads Σ∞ = σ∞ and shows that, in the linear viscoelastic case with a viscoelastic Poisson's ratio of the matrix equal to 0.2, the long-term “effective” macroscopic stress Σ∞ that acts at the scale of the concrete sample is equal to the long-term microscopic stress σ∞ that acts on the C-S-H gel.

  • addendum to is long term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self desiccation
    Cement and Concrete Research, 2019
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Prof. F.-J. Ulm brought to our attention that we forgot to include an important reference in our manuscript. Indeed, Ulm et al. [1] showed that, for 5 concretes that differed in their water-to-cement ratio and for which basic Creep and autogenous shrinkage were measured by Le Roy [2], the long-term kinetics of autogenous shrinkage could be explained by Creep of the solid skeleton under the action of an internal pore pressure. Their conclusion was based on the observed linearity of the relationship between basic Creep compliance and increase in autogenous shrinkage in the long term. From the slope of this linear relationship, they back-calculated an “effective pore pressure” displayed in Fig. 1. Interestingly, this uniaxial “effective pore pressure” – merely calculated from macroscopic observables – is in very good agreement (both in terms of magnitude and in terms of trend with water-to-cement ratio) with the capillary stresses that we estimated at the pore scale with the help of micromechanics (see Fig. 6 in our manuscript). The reason for this agreement lies in Eq. 16 of our manuscript, which reads Σ∞ = σ∞ and shows that, in the linear viscoelastic case with a viscoelastic Poisson's ratio of the matrix equal to 0.2, the long-term “effective” macroscopic stress Σ∞ that acts at the scale of the concrete sample is equal to the long-term microscopic stress σ∞ that acts on the C-S-H gel.

  • Is long-term autogenous shrinkage a Creep Phenomenon induced by capillary effects due to self-desiccation?
    Cement and Concrete Research, 2018
    Co-Authors: Abudushalamu Aili, Matthieu Vandamme, Jean Michel Torrenti, Benoit Masson
    Abstract:

    Long-term shrinkage and Creep of concrete can impact the lifetime of concrete structures. Basic Creep of cementitious materials is now known to be non-asymptotic and evolve logarithmically with time at large times. However, the long-term kinetics of autogenous shrinkage is not systematically analyzed. Here we first aim at finding out how autogenous shrinkage evolves with time at long term. We analyze all experimental data available in the literature and find that autogenous shrinkage evolves logarithmically with respect to time at long term, like basic Creep. Then, by considering concrete as a multiscale material, we obtain the bulk Creep modulus of the calcium silicate hydrate gel. In the end, we show that the kinetics of long-term autogenous shrinkage can be a viscoelastic response to self-desiccation by comparing the mechanical stress that should be applied to explain this long-term kinetics of autogenous shrinkage with the capillary force due to self-desiccation.

M Naghikhani - One of the best experts on this subject based on the ideXlab platform.

  • “Research Note” FAILURE ANALYSIS OF HP40-Nb MODIFIED PRIMARY REFORMER TUBE OF AMMONIA PLANT *
    2014
    Co-Authors: S. A. Jenabali, M Naghikhani
    Abstract:

    Abstract – Micro-structural failure analysis of the heat resisting HP40 Nb modified alloy was studied by light and electron methods. Samples from the failed reformer furnace tube were cut and prepared for metallographic examination. Examination with electron microscope was carried out with secondary and backscattered electron detectors; x-ray analysis was conducted at the grain boundary areas. In tubes, which are filled with a supported nickel catalyst, methane reacts with steam, carbondioxide and oxygen into synthesis gas. The overall heat of reactions may be positive, zero, or negative, depending on the process conditions. The catalyst plays a key role in developing overheating in the tubes. The catalyst deactivation caused by feeding is heavier than that designed hydrocarbon. Using an unsuitably designed hydrocarbon causes a thin layer of carbon coating on the catalyst surface. Overheating due to catalyst poisoning caused Creep failure. The presence of inter-granular voids in the microstructure of the failed tube seems to be the result of Creep Phenomenon

  • Creep life assessment of primary reformer hp40 nb modified steel tube of an ammonia plant
    International Journal of Engineering, 2004
    Co-Authors: S Jenabali A Jahromi, M Naghikhani
    Abstract:

    Assessment of Creep damage and residual Creep life of a cast HP 40 Nb Mod. Reformer tube was performed, wherein the experimental Larson–Miller diagram and area fraction of Creep voids were adopted. The state of damage of the tube in service was metallographically analyzed by using light and electron microscopy. Samples from the serviced reformer furnace tube were cut and prepared for void examination and Creep test at 940oC-1000oC under 20-30 MPa stress. Microstructural examination was carried out with an Scanning electron microscope with secondary and backscattered electron detectors. Inter-granular voids in the microstructure of the worked tube as a result of a Creep Phenomenon are ranked relating to the remaining life.