Chloride Ion Penetration Resistance and Pore Structure of Magnesium Silicate Hydrate (M-S-H) Mortars

Zhang, Tingting; He, Ziming; Wu, Zhenlin; Han, Junnan

doi:10.2991/icmea-17.2018.36

Cited by 3 publications

(2 citation statements)

References 14 publications

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“…Porosity and permeability properties in M-S-H cements were found to be similar or even more favourable compared to Portland cement products [115,116]. Pore sizes somewhat smaller, and chloride diffusion coefficients much lower compared to Portland cement have been reported [117]. Towards ingress of calcium ions, M-S-H seems to be quite stable as well, at least at low pH, only a very slow ingress of Ca ions has been observed [38].…”

Section: Durabilitymentioning

confidence: 82%

MgO‐based binders

Lothenbach,

Bernard,

German

et al. 2023

ce papers

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To limit global temperature rise to below 2°C, we need to radically and rapidly change the way we build and use materials, since construction is responsible for 20‐40% of industrial CO2 emissions. Magnesium carbonate‐based cements have the potential to become a major carbon sink in construction industry, as CO2 will not be emitted during their production, but CO2 will rather be bound during hardening. Two different reaction mechanisms lead to setting and hardening of such HMC cements: i) hydration of MgO‐Mg‐carbonate, also in blends with silica and other mineral additions, in the presence of water or salt solutions (such as sodium bicarbonate solution) at ambient conditions or ii) carbonation hardening of MgO‐based systems at increased CO2 partial pressure and/or at increased temperatures.However, the utilization of hydrated magnesium carbonate and magnesium silicate cements is currently hampered by the lack of systematic experiments and of fundamental understanding of the factors affecting the hardening process, mechanical properties, long‐term behavior and durability. In particular, the role of temperature, relative humidity and addition of supplementary cementitious materials and/or industrial by‐products has not been systematically investigated. We need knowledge both on the practical side through systematic experiments with pastes, mortars and concretes as well as on a fundamental level through solubility and sorption experiments and thermodynamic modelling. In addition, reaction kinetics need to be optimized as well as the early formation of the preferred phases (stability enhancement) to develop efficient HMC cements for construction. Due to the socio‐economic relevance of cement and concrete, the impact of such “carbon”‐negative cements may go beyond a purely scientific one and lead to technological breakthroughs to the benefit of environment and society.

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Section: Durabilitymentioning

confidence: 82%

MgO‐based binders

Lothenbach,

Bernard,

German

et al. 2023

ce papers

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“…6,7,21,22 The hydrated M-S-H paste is reported to have a microstructure dominated by pores smaller than 10 nm, as measured using mercury intrusion porosimetry (MIP). 23,24 However, information on the evolution of microstructure with hydration and the effect of initial mix composition is sparse. Tran et al 25 carried out a preliminary investigation on the development of pore structure characteristics of M-S-H binder concrete with age using different durability indicators.…”

Section: Introductionmentioning

confidence: 99%

Pore structure characteristics of MgO–SiO₂binder

2021

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This paper reports on an investigation into the pore structure characteristics of MgO-SiO 2 binders. Paste specimens were prepared using two MgO/SiO 2 ratios (1 and 1.5), two silica sources (Silica fume-SF and Metakaolin-MK), two water to binder ratios (0.5 and 0.6) and compared to a portland cement (PC) control mix. Mercury intrusion porosimetry was used to understand the evolution of pore structural features of the binder with hydration period. A continued reduction in porosity and refinement of pores was observed with the progress in hydration irrespective of the type of the silica source or the initial MgO/SiO 2 ratio. The MgO-MK mixes exhibited a finer and denser microstructure as compared to the equivalent MgO-SF mixes. The formation of hydrotalcite in addition to M-S-H in MgO-MK mixes was postulated to be the primary reason for the difference in microstructural characteristics, compared to MgO-SF mixes. The space-filling capacity of hydration products of MgO-MK binder was found to be better than PC.

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Research progress on magnesium silicate hydrate phases and future opportunities

Bernard

2022

RILEM Tech Lett

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This short letter summaries the latest research on the structure and thermodynamic modelling of the magnesium silicate hydrates (M-S-H) phases. M-S-H structure is comparable to hydrated clays, with a smaller and rounder microstructures compared to clay platelets. Similar to clay minerals, M-S-H can incorporate ions such as aluminium and hydrated exchangeable cations to compensate the negative surface charge. This fundamental understanding of M-S-H structure allowed to develop structure-based thermodynamic models, which can further help to optimise the conditions for M-S-H formation and its use as cementitious materials. Optimized binders containing M-S-H have the advantages of presenting: i) good mechanical properties, ii) dense microstructure and potentially good resistances to leaching and iii) low pH values. These types of binders could therefore be used for cement products with non-steel reinforcement, for the encapsulation of specific wastes, for products containing natural fibres or for the clay stabilisation, etc.

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Chloride Ion Penetration Resistance and Pore Structure of Magnesium Silicate Hydrate (M-S-H) Mortars

Cited by 3 publications

References 14 publications

MgO‐based binders

MgO‐based binders

Pore structure characteristics of MgO–SiO₂binder

Research progress on magnesium silicate hydrate phases and future opportunities

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Chloride Ion Penetration Resistance and Pore Structure of Magnesium Silicate Hydrate (M-S-H) Mortars

Cited by 3 publications

References 14 publications

MgO‐based binders

MgO‐based binders

Pore structure characteristics of MgO–SiO2binder

Research progress on magnesium silicate hydrate phases and future opportunities

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Pore structure characteristics of MgO–SiO₂binder