5-year chemico-physical evolution of concrete–claystone interfaces, Mont Terri rock laboratory (Switzerland)

Mäder, Urs; Jenni, Andreas; Lerouge, Cathérine; Gaboreau, Stéphane; Miyoshi, Seiji; Kimura, Yukinobu; Cloet, Veerle; Fukaya, Masaaki; Claret, Francis; Otake, Tsubasa; Shibata, Masahito; Lothenbach, Barbara

doi:10.1007/s00015-016-0240-5

Cited by 58 publications

(67 citation statements)

References 28 publications

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“…Mg-Al layered double hydroxide (LDH) type phases are structurally similar to hydrotalcite and typically occur as secondary reaction products in hydrated Portland cements [67] and in alkali-activated granulated blast furnace slag (GBFS) [68,69]. the data at 25°C are summarised in Figure 8A and B.…”

Section: Mg-al Layered Double Hydroxide (Hydrotalcite-like Phase)mentioning

confidence: 99%

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Cemdata18: A chemical thermodynamic database for hydrated Portland cements and alkali-activated materials

Lothenbach

Kulik

Matschei

et al. 2019

Cement and Concrete Research

796

319

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Thermodynamic modelling can reliably predict hydrated cement phase assemblages and chemical compositions, including their interactions with prevailing service environments, provided an accurate and complete thermodynamic database is used. Here, we summarise the Cemdata18 database, which has been developed specifically for hydrated Portland, calcium aluminate, calcium sulfoaluminate and blended cements, as well as for alkali-activated materials. It is available in GEMS and PHREEQC computer program formats, and includes thermodynamic properties determined from various experimental data published in recent years. Cemdata18 contains thermodynamic data for common cement hydrates such as C-S-H, AFm and AFt phases, hydrogarnet, hydrotalcite, zeolites, and M-S-H that are val-Cemdata18 includes a comprehensive selection of cement hydrates commonly encountered in Portland cement (PC) systems in the temperature range of to 100°C, including calcium silicate hydrate (C-S-H), magnesium silicate hydrate (M-S-H), hydrogarnet, hydrotalcite-like phases, some zeolites, AFm and AFt phases, and various solid solutions used to describe the solubility of these phases. Solubility constants have generally been calculated based on critical reviews of all available experimental data and from additional experiments made either to obtain missing data or to verify existing data. Additional solubility data were measured and compiled using temperatures ranging from 0 to 100°C in many instances, as documented in [9, 12, 27, 28]. Numerous solid solutions among AFm and AFt phases, siliceous hydrogarnets, hydrotalcite-like phases, C-S-H, and M-S-H have been observed and are included in Cemdata18. Several C-S-H solid solution models, as well as two models for hydroxide-hydrotalcite are available in Cemdata18. The CSHQ model from [11] and the OH-hydrotalcite end member with Mg/Al = 2 are well adapted for PC. Although the CSHQ model is able to describe the entire range of Ca/Si ratios encountered, it is best used for high Ca/Si C-S-H, as it still lacks the ability to predict aluminium uptake, which is of less importance for Portland cements than for blended cements. For alkali activated binders, the calcium (alkali) aluminosilicate hydrate (C-(N-)A-S-H) gel model, with lower calcium but higher aluminium and alkali content than in the C-S-H type phase which exists in hydrated PC, and a Mg-Al layered double hydroxide with variable Mg/Al ratio, are available. This paper summarises Cemdata18, which includes the most important additions to the Cemdata07 and Cemdata14 databases in recent years. It also discusses the relevance and implications of these additions, and compares Cemdata07 and Cemdata18, accounting for their main differences. Summaries

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Section: Mg-al Layered Double Hydroxide (Hydrotalcite-like Phase)mentioning

confidence: 99%

“…The formation of magnesium silicates hydrate (M-S-H) has been observed at the interfacial zone of cement paste with clays [67,108,109] and/or as secondary products from the degradation of cement pastes by groundwater or seawater [110][111][112]. Figure 11.…”

Section: Magnesium Silicate Hydratesmentioning

confidence: 99%

Cemdata18: A chemical thermodynamic database for hydrated Portland cements and alkali-activated materials

Lothenbach

Kulik

Matschei

et al. 2019

Cement and Concrete Research

796

319

View full text Add to dashboard Cite

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“…The formation of magnesium silicates hydrate (M-S-H), has been observed at the interfacial zone of cement-based materials in contact with clays (Dauzères et al, 2016;Garcia Calvo et al, 2010;Jenni et al, 2014;Lerouge et al, 2017;Mäder et al, 2017) and/or as secondary products from the degradation of cementitious materials by groundwater or seawater (Bonen and Cohen, 1992;Jakobsen et al, 2016;Santhanam et al, 2002). The combination of leaching and carbonation induces a pH decrease at the surface of the cement sample, resulting in the decalcification of calcium silicate hydrate (C-S-H) and the formation of amorphous silica which then reacts with magnesium to yield a Mg-enriched phase referred as magnesium silicate hydrate (M-S-H) (Bonen and Cohen, 1992;Dauzères et al, 2016;De Weerdt and Justnes, 2015;Jakobsen et al, 2016;Jenni et al, 2014;Lerouge et al, 2017;Mäder et al, 2017;Santhanam et al, 2002). M-S-H phases have been synthesized in the laboratory (Brew and Glasser, 2005;d'Espinose de Lacaillerie et al, 1995;Nied et al, 2016;Roosz et al, 2015;Walling et al, 2015); its structure has also been investigated by molecular modelling (Pedone et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Magnesium and calcium silicate hydrates, Part I: Investigation of the possible magnesium incorporation in calcium silicate hydrate (C-S-H) and of the calcium in magnesium silicate hydrate (M-S-H)

Bernard

Lothenbach

Cau-dit-Coumes

et al. 2018

Applied Geochemistry

110

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Calcium silicate hydrate (C-S-H) and magnesium silicate hydrate (M-S-H) have been described as two separate phases. This work investigates their stability domains and the possible uptake of small amounts of magnesium by C-S-H or, reversely, the uptake of small amounts of calcium by M-S-H. The phases, synthesized by co-precipitation, are characterized using a large panel of techniques (thermogravimetry analysis, X-ray diffraction, X-ray pair distribution function analysis, 29 Si MAS-NMR spectroscopy, 17 measurement of zeta potential and cation exchange capacity) while the compositions of the solutions at 18 equilibrium are determined by ion chromatography and pH measurements. Syntheses of C-S-H samples 19 in the presence of magnesium ((Ca+Mg)/Si = 0.8 and Mg/Si = 0.05 or 0.10) yield two separate phases: 20

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“…Experimental literature documents chemical and mineralogical changes at claycement interfaces [1][2][3][4][5][6][7][8][9][10]. Local decalcification (instability of portlandite, calcium silicate hydrate (C-S-H), and ettringite) is the main alteration of the cement.…”

Section: Introductionmentioning

confidence: 99%

Reactive Transport Simulation of Low-pH Cement Interacting with Opalinus Clay Using a Dual Porosity Electrostatic Model

Jenni

Mäder

2021

Minerals

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Strong chemical gradients between clay and concrete porewater lead to diffusive transport across the interface and subsequent mineral reactions in both materials. These reactions may influence clay properties such as swelling behaviour, permeability or radionuclide retention, which are relevant for the safety of a radioactive waste repository. Different cement types lead to different interactions with Opalinus Clay (OPA), which must be understood to choose the most suitable material. The consideration of anion-depleted porosity due to electrostatic repulsion in clay modelling substantially influences overall diffusive transport and pore clogging at interfaces. The identical dual porosity model approach previously used to predict interaction between Portland cement and OPA is now applied to low-alkali cement—OPA interaction. The predictions are compared with corresponding samples from the cement-clay interaction (CI) experiment in the Mont Terri underground rock laboratory (Switzerland). Predicted decalcification of the cement at the interface (depletion of C–S–H and absence of ettringite within 1 mm from the interface), the Mg enrichment in clay and cement close to the interface (neoformation of up to 17 vol% Mg hydroxides in concrete, and up to 6 vol% in OPA within 0.6 mm at the interface), and the slightly increased S content in the cement 3–4 mm away from the interface qualitatively match the sample characterisation. Simulations of Portland cement—OPA interaction indicate a weaker chemical disturbance over a larger distance compared with low-pH cement—OPA. In the latter case, local changes in porosity are stronger and lead to predicted pore clogging.

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5-year chemico-physical evolution of concrete–claystone interfaces, Mont Terri rock laboratory (Switzerland)

Cited by 58 publications

References 28 publications

Cemdata18: A chemical thermodynamic database for hydrated Portland cements and alkali-activated materials

Cemdata18: A chemical thermodynamic database for hydrated Portland cements and alkali-activated materials

Magnesium and calcium silicate hydrates, Part I: Investigation of the possible magnesium incorporation in calcium silicate hydrate (C-S-H) and of the calcium in magnesium silicate hydrate (M-S-H)

Reactive Transport Simulation of Low-pH Cement Interacting with Opalinus Clay Using a Dual Porosity Electrostatic Model

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