Thermodynamic properties of C-S-H, C-A-S-H and M-S-H phases: Results from direct measurements and predictive modelling

Roosz, Cédric; Vieillard, Philippe; Blanc, Philippe; Gaboreau, Stéphane; Gailhanou, Hélène; Braithwaite, D.; Montouillout, V.; Denoyel, Renaud; Hénocq, Pierre; Madé, Benoı̂t

doi:10.1016/j.apgeochem.2018.03.004

Cited by 79 publications

(29 citation statements)

References 67 publications

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“…The solubility products of the crystalline clay minerals (red diamonds in Figure 8) were somewhat lower than those of M-A-S-H of similar compositions, consistent with the observation that M-A-S-H may be a poorly ordered precursor and thus slightly less stable than their crystalline analogues. Note that the data of vermiculite and saponite also show the same trend as M-A-S-H: the solubility decreases with increasing Mg/Si ratio [13,22,64] and varies only little with aluminum content.…”

mentioning

confidence: 57%

Aluminum incorporation into magnesium silicate hydrate (M-S-H)

Bernard

Lothenbach

Cau-dit-Coumes

et al. 2020

Cement and Concrete Research

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mentioning

confidence: 57%

Aluminum incorporation into magnesium silicate hydrate (M-S-H)

Bernard

Lothenbach

Cau-dit-Coumes

et al. 2020

Cement and Concrete Research

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“…Two model pastes were used in this study: a tricalcium silicate (C3S) paste (C/S = 3.0), namely a matrix of C-S-H embedding portlandite crystals and another one composed of C-S-H only with a target C/S ratio of 1.4. Note that the latter is more or less the highest value that can be obtained without precipitating portlandite [43][44][45][46][47][48][49]. The former is hereafter referred to as the C3S paste and the latter as the C-S-H paste.…”

Section: Methodsmentioning

confidence: 99%

Carbonation of model cement pastes: The mineralogical origin of microstructural changes and shrinkage

Kangni-Foli

Poyet

Bescop

et al. 2021

Cement and Concrete Research

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This study explored the reactive processes of atmospheric carbonation and the consequences with respect to cementitious materials. Two model pastes were used: hydrated C3S (including C-S-H and portlandite) and a paste prepared by hydrating a blend of C3S and nanosilica (including C-S-H only). The two pastes were carbonated under accelerated conditions in the laboratory. The resulting mineralogical assemblage was examined using X-ray diffraction, thermogravimetric analysis and nuclear magnetic resonance. The microstructural changes were studied by X-ray tomography and porosimetry, and their macroscopic impacts were evaluated through gas diffusion and shrinkage measurements. The use of model pastes allowed for the evaluation of the change in solid volume induced by the carbonation of C-S-H. C-S-H decalcification and subsequent silica chain polymerisation were found responsible for carbonation shrinkage (and potentially cracking). Finally, the results highlight the protective role of portlandite: portlandite helped in limiting C-S-H decalcification and then reducing carbonation shrinkage and cracking.

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“…The role of confined water in C-S-H micropores was demonstrated through molecular dynamic simulation [34,35]. Because of these points, understanding the distribution of water in C-S-H and their thermodynamic and hydration properties is of prime importance when considering the strength and transfer properties of cement materials [36][37][38][39][40][41]. Nonetheless, all the hydrates must be considered as they play a role in the cement-paste properties.…”

Section: Cement-based Materialsmentioning

confidence: 99%

Reinforced concrete structures: A review of corrosion mechanisms and advances in electrical methods for corrosion monitoring

Rodrigues

Gaboreau

Gance

et al. 2021

Construction and Building Materials

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Steel corrosion is the main cause of deterioration of reinforced concrete (RC) structures. We provide an up-to-date review on corrosion mechanisms and recent advances in electrical methods for corrosion monitoring. When assessing corrosion mechanism, the inherent heterogeneity of RC structures and the significant effect of environmental factors remain major issues in data interpretations. The steel surface condition and local inhomogeneities at the steel-concrete interface appear to have an important effect on corrosion initiation. Considering uniform corrosion in atmospherically exposed reinforced concrete, the two main influencing factors of the corrosion process are the water content and the pore structure at the steel-concrete interface. However, irrespective of the depassivation mechanism, i.e. carbonation or chloride-induced corrosion, nonuniform corrosion is expected to be the main process for RC structures due to local variations in environmental exposure or the presence of interconnected rebars with different properties. Future studies may then be focused on their effect on macrocell corrosion to gain further insights in the corrosion mechanisms of RC structures. Concerning corrosion monitoring using electrical methods, the half-cell potential technique with potential mapping is accurate for locating areas with a high corrosion risk. Recent developments in the measurement of concrete resistivity have shown that the use of electrical resistivity tomography allows to consider appropriately the inherent heterogeneity of concrete and provides more insights on transport phenomena (e.g. water and salts ingress) in the material. Nevertheless, during the corrosion propagation stage, the polarization resistance remains the most important parameter to be determined as it provides quantitative information of the corrosion rate. If conventional three-electrode configuration methods can supply an accurate determination in the case of uniform corrosion, they often fail in the case of macrocell corrosion in field experiments. Recent advances have shown that a four-electrode configuration without any connection to the rebar can rather be used for the non-destructive testing and evaluation of corrosion. If studies are still required to quantify the corrosion rate, this method appears sensitive to localized corrosion and thus more suitable to field investigations. Finally, the coupling of numerical simulations with complementary electrical and other non-destructive testing methods is essential for consolidating the results to provide a better diagnosis of the service life of RC structures.

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Thermodynamic properties of C-S-H, C-A-S-H and M-S-H phases: Results from direct measurements and predictive modelling

Cited by 79 publications

References 67 publications

Aluminum incorporation into magnesium silicate hydrate (M-S-H)

Aluminum incorporation into magnesium silicate hydrate (M-S-H)

Carbonation of model cement pastes: The mineralogical origin of microstructural changes and shrinkage

Reinforced concrete structures: A review of corrosion mechanisms and advances in electrical methods for corrosion monitoring

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