Micromechanics analysis of thermal expansion and thermal pressurization of a hardened cement paste

Ghabezloo, Siavash

doi:10.1016/j.cemconres.2011.01.023

Cited by 59 publications

(28 citation statements)

References 42 publications

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“…A comparison with the results presented in Figure 3 shows that the effective thermal expansion coefficient of the hardened cement paste should decrease with porosity increase. This is compatible with the experimental results of Zeng et al (2012) and also with the results of the micromechanics modellings of Ghabezloo (2011) which show the reduction of the drained thermal expansion coefficient with the porosity increase for cement pastes with different water-to-cement ratios.…”

Section: Figuresupporting

confidence: 91%

“…In a simplified view, a completely hydrated cement paste can be seen as a mixture of C-S-H, Portlandite (CH) and porosity. The thermo-elastic properties of the C-S-H solid are not clearly known, however an indirect estimation of these parameters has been done by Ghabezloo ( , 2011 by the back analysis of the results of macro-scale experimental study of Ghabezloo et al (2008) using a micromechanics model. The bulk modulus and volumetric thermal expansion coefficient of the C-S-H solid have been evaluated respectively equal to 25 GPa and 42 × 10 −6 ( • C) −1 .…”

Section: Figurementioning

confidence: 99%

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Effect of Porosity on the Thermal Expansion Coefficient of Porous Materials

Ghabezloo

2013

Poromechanics V

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The effect of porosity on the thermal expansion coefficient of porous materials is studied for two different cases. The first case concerns the thermo-elastic evolution of the porosity of a given material for which it is shown that the drained thermal expansion coefficients increases with the porosity increase. The second case concerns porous materials with similar solid phase and different porosity which is studied using the homogenization method. A parametric study shows the coupled effect of the thermal expansions and bulk moduli of the solid constituents on the thermal expansion coefficient-porosity relationship. Depending on the combination of the parameters, the thermal expansion coefficient can increase or decrease with the porosity. The effective thermal expansion increases with the porosity when a solid constituent has higher thermal expansion but lower rigidity than the other constituent. Generally, there is no unique thermal expansion-porosity relationship that can be applied to all porous materials.

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Section: Figuresupporting

confidence: 91%

Section: Figurementioning

confidence: 99%

Effect of Porosity on the Thermal Expansion Coefficient of Porous Materials

Ghabezloo

2013

Poromechanics V

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“…microthermoporomechanics backanalysis [70]. The CSH density is found to decrease with increasing Ca∶Si ratio, 2.55 g=cm 3 > ρ CSH > 2.35 g=cm 3 .…”

Section: Nanoscale Heat-capacity Calculationsmentioning

confidence: 87%

Physical Origins of Thermal Properties of Cement Paste

2015

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Despite the ever-increasing interest in multiscale porous materials, the chemophysical origin of their thermal properties at the nanoscale and its connection to the macroscale properties still remain rather obscure. In this paper, we link the atomic-and macroscopic-level thermal properties by combining tools of statistical physics and mean-field homogenization theory. We begin with analyzing the vibrational density of states of several calcium-silicate materials in the cement paste. Unlike crystalline phases, we indicate that calcium silicate hydrates (CSH) exhibit extra vibrational states at low frequencies (< 2 THz) compared to the vibrational states predicted by the Debye model. This anomaly is commonly referred to as the boson peak in glass physics. In addition, the specific-heat capacity of CSH in both dry and saturated states scales linearly with the calcium-to-silicon ratio. We show that the nanoscale-confining environment of CSH decreases the apparent heat capacity of water by a factor of 4. Furthermore, full thermal conductivity tensors for all phases are calculated via the Green-Kubo formalism. We estimate the mean free path of phonons in calcium silicates to be on the order of interatomic bonds. This satisfies the scale separability condition and justifies the use of mean-field homogenization theories for upscaling purposes. Upscaling schemes yield a good estimate of the macroscopic specific-heat capacity and thermal conductivity of cement paste during the hydration process, independent of fitting parameters.

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“…In a similar approach, Sun and Scherer (2010a and b) excluded the volume of interlayer water in their evaluation of the active porosity of mortar samples. Ghabezloo et al (2008) and Ghabezloo (2010 and2011) also demonstrated that only a proportion of the total porosity of cement, corresponding to the mercury intruded porosity, was to consider when dealing with its poroelastic response. This extension to claystones of findings on other porous material in which mineral/water interactions are also significant confirms the similarity between both materials.…”

Section: Biot Effective Stress Coefficientsmentioning

confidence: 99%

Active porosity in swelling shales: insight from the Callovo-Oxfordian claystone

Belmokhtar

Delage

Ghabezloo

et al. 2018

Géotechnique Letters

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In swelling claystones, significant clay-water interactions take place along the faces of the smectites minerals contained in the clay fraction, giving rise to the distinction between free water and adsorbed water. Further insight was recently gained by means of microstructure investigations, showing that the hydration mechanisms of pure or compacted smectites also hold to explain the hydration and swelling behaviour of the Callovo-Oxfordian (COx) claystone, a possible host rock for deep radioactive waste disposal in France. In this rock, the proportion of water molecules adsorbed in intra-platelets pores was recently estimated to around 25% of the total porosity, with 75% of the porosity containing free water. Based on these findings, the data of high precision poroelastic measurements conducted in an isotropic compression cell showed that the porosity to account for a proper calculation of the Skempton parameter is not the total porosity, but the 75% proportion corresponding to free water. This conclusion is believed to be of some interest with respect to the prediction of the rock response around the disposals at great depth, given that hydromechanical numerical simulations are often carried out within the framework of poroelasticity.

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Micromechanics analysis of thermal expansion and thermal pressurization of a hardened cement paste

Cited by 59 publications

References 42 publications

Effect of Porosity on the Thermal Expansion Coefficient of Porous Materials

Effect of Porosity on the Thermal Expansion Coefficient of Porous Materials

Physical Origins of Thermal Properties of Cement Paste

Active porosity in swelling shales: insight from the Callovo-Oxfordian claystone

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