Development of low pH cement systems forming magnesium silicate hydrate (M-S-H)

Zhang, Ting Ting; Cheeseman, Christopher R.; Vandeperre, Luc

doi:10.1016/j.cemconres.2011.01.016

Cited by 278 publications

(186 citation statements)

References 13 publications

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“…The latter two were included as these crystalline materials have Mg:Si ratios similar to M-S-H gel [7,8,12].…”

Section: Mg 2+ (Aq) + 2oh -(Aq) → Mg(oh)2(s)mentioning

confidence: 99%

“…The experimental measurements of pH and solution chemistry were compared as much as possible with predictions made using Visual MINTEQ 2.6 [11], a windows implementation of the MINTEQA2 algorithm [12] for calculation of geochemical aqueous equilibria, which uses the thermochemical data contained within [20]. Unfortunately no information was found for the interaction of sodium hexametaphosphate with magnesium.…”

Section: Thermodynamic Modelling Of the Solution Chemistrymentioning

confidence: 99%

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Role of sodium hexametaphosphate in MgO/SiO2 cement pastes

Jia

Wang

et al. 2016

Cement and Concrete Research

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The extent of reaction between magnesium oxide (MgO) and silica fume (SiO2) is normally limited and mixes require high water contents to give suitable rheology. The use of considerably lower water contents and the formation of magnesium silicate hydrate (M-S-H) gel as a binding phase is made possible by adding sodium hexametaphosphate (Na-HMP) to the mix water prior to the addition of MgO and SiO2. This results in the formation of extensive reaction products and cured samples with high compressive strength and low porosity. In this work, the effect of Na-HMP on the hydration of MgO/SiO2 mixes is investigated using high water to solids ratio samples to allow monitoring of pH and the solution chemistry during hydration. It is shown that a relatively small amount of Na-HMP inhibits the formation of Mg(OH)2 when MgO is hydrolyzed. It is proposed that this is due to adsorption of phosphate species on the MgO which inhibits the nucleation of the Mg(OH)2.. This gives rise to high Mg 2+ species in solution and elevated pH (>12) conditions relative to when Mg(OH)2 forms. In contrast, the phosphate does not suppress formation of M-S-H gel. In combination with the enhanced dissolution rate of SiO2 at high pH, M-S-H gel can form quickly without competition for Mg 2+ ions by Mg(OH)2 precipitation. Incorporating the optimum concentration of Na-HMP into the mix water therefore transforms the properties of cement paste and mortar samples formed by reacting MgO and SiO2.

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“…The latter two were included as these crystalline materials have Mg:Si ratios similar to M-S-H gel [7,8,12].…”

Section: Mg 2+ (Aq) + 2oh -(Aq) → Mg(oh)2(s)mentioning

confidence: 99%

Section: Thermodynamic Modelling Of the Solution Chemistrymentioning

confidence: 99%

Role of sodium hexametaphosphate in MgO/SiO2 cement pastes

Jia

Wang

et al. 2016

Cement and Concrete Research

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“…The evolution of pH over time in MgO-SiO 2 slurries representing the cement samples was measured following the procedures of previous studies [20]. 10 g of blended powders, in ratios according to One of the key criteria used to select the best formulation was mechanical performance.…”

Section: Selection Of the Optimal Binder Matrixmentioning

confidence: 99%

“…In initial studies of this system, a high content of bonding M-S-H was achieved with satisfactory mechanical properties [19]. Whereas this type of cement historically attracted limited interest, during the last decade it has become an attractive alternative to Portland cement in specific applications, such as this, due to its low alkalinity (pH < 11) [20,21] and potentially good mechanical performance [22,23].…”

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confidence: 99%

Optimization of the MgO SiO2 binding system for fiber-cement production with cellulosic reinforcing elements

et al. 2016

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“…Literature has indicated that the hydration products of MgO-SiO 2 -H 2 O system are primarily composed of Mg(OH) 2 and MSH gel, which is formed by the reaction of MgO and amorphous silica in the presence of sodium hexametaphosphate (Na-HMP) [1][2][3]. The properties of magnesium silicate hydrate cement have also been studied by some scholars [4,5].…”

Section: Introductionmentioning

confidence: 99%

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

Zhang¹,

He²,

Wu³

et al. 2018

Proceedings of the 4th Annual International Conference on Material Engineering and Application (ICMEA 2017)

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Abstract-The main purpose of this paper is to study the chloride ion penetration resistance and pore structure of magnesium silicate hydrate cement (MSH) mortars. The chloride ion penetration resistance of MSH mortars with different water-to-cement ratios (0.5, 0.55, 0.6) and different sand rates (25%, 50%, 75%) was studied and compared to ordinary Portland cement (OPC) mortars. The pore structure of magnesium silicate hydrate mortar was tested using mercury intrusion porosimetry (MIP). The results indicate that the chloride ion diffusion coefficient becomes larger with an increase in the water-to-cement ratio and sand rate; the coefficient of MSH mortars is much smaller than that of OPC mortars. The results of MIP show that MSH mortars generally have gel pores measuring less than 10nm; however, the pore size of OPC mortars is dominated by pores measuring 10nm to 100nm. Finally, MSH mortars were found to be less porous than OPC mortars.

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Development of low pH cement systems forming magnesium silicate hydrate (M-S-H)

Cited by 278 publications

References 13 publications

Role of sodium hexametaphosphate in MgO/SiO2 cement pastes

Role of sodium hexametaphosphate in MgO/SiO2 cement pastes

Optimization of the MgO SiO2 binding system for fiber-cement production with cellulosic reinforcing elements

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

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