A study of the system magnesium oxide-magnesium chloride-water and the heat of formation of magnesium oxychloride

Newman, Edwin S.

doi:10.6028/jres.054.039

Cited by 12 publications

(9 citation statements)

References 7 publications

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“…Dinnebier et al postulated that the 9‐1‐4 phase was rapidly formed during MOC hydration and eventually transformed into phase 3. Phase 5 was also proposed to exist as a metastable phase at room temperature, before converting to the stable phase 3 . This was confirmed by Melanie, who studied the solubility equilibria of the ternary system Mg(OH) 2 ‐MgCl 2 ‐H 2 O at temperatures from 298 to 393 K applying equilibration periods of up to 3.5 years.…”

Section: Phase Composition In Mgo‐mgcl2‐h2o Systemmentioning

confidence: 78%

“…Phase 5 was also proposed to exist as a metastable phase at room temperature, before converting to the stable phase 3. 33,35,36 This was confirmed by Melanie 37 , who studied the solubility equilibria of the ternary system Mg(OH) 2 -MgCl 2 -H 2 O at temperatures from 298 to 393 K applying equilibration periods of up to 3.5 years. The adjustment of equilibrium was realized by isothermal saturation method 37 .…”

Section: Phase Composition In Mgo-mgcl -H O Systemmentioning

confidence: 82%

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Recent development in magnesium oxychloride cement

Guo

Zhang

Soe³

et al. 2018

Structural Concrete

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This paper presents a review for the key literatures on magnesium oxychloride cement (MOC) to establish a comprehensive and insightful understanding of MOC. The main aim of this review is to identify the most common problems in the development and application of the MOC and the various methods to solve these problems. The characteristics of MOC including composition of hydration phases, strength development, and durability are reviewed. In particular, the various factors influencing the water resistance of MOC, the most critical characteristics of MOC, such as the reactivity of magnesium oxide, additives, and curing conditions are reviewed. Finally, the methods to improve water resistance and its related issues of MOC from the literature are summarized and future research is proposed.

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Section: Phase Composition In Mgo‐mgcl2‐h2o Systemmentioning

confidence: 78%

Section: Phase Composition In Mgo-mgcl -H O Systemmentioning

confidence: 82%

Recent development in magnesium oxychloride cement

Guo

Zhang

Soe³

et al. 2018

Structural Concrete

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MgO + {normalH}^{+} (aq) \to {Mg}^{2 +} (aq) + {OH}^{-} (aq)

x {Mg}^{2 +} (aq) + (z + y) {normalH}_{2} O \overset{{OH}^{-}}{false⟶} {(][, {Mg}_{x} {(OH)}_{y} {({normalH}_{2} O)}_{z})}^{()(, 2 x - y)} (aq) + y {normalH}^{+} (aq)

{(][, {Mg}_{x} {(OH)}_{y} {({normalH}_{2} O)}_{z})}^{()(, 2 x - y)} (aq) + {Cl}^{-} (aq) + {OH}^{-} (aq) + {normalH}_{2} O \to gel

gel \to {(][, {Mg}_{3} {(OH)}_{5} {({normalH}_{2} O)}_{m})}^{+} {Cl}^{-} \cdot (4 - m) {normalH}_{2} O (5 - phase)

…”

Section: Resultsmentioning

confidence: 99%

“…Higher ALC content indicates that the reaction of the MOC slurry yielded more the gel phase, and less the crystalline oxychloride phases. According to the previous researches [17][18][19][20][21][22]29 , The occurrence of these reactions is dominantly governed by the total concentration of Mg 2+ and Cl − ions in the liquid phase of MOC slurry and the pH value of the liquid phase, [17][18][19][20][21][22]29 which actually depends on initial MgO/MgCl 2 and H 2 O/MgCl 2 molar ratios in the system. 22,23 The dissolution of MgO in a higher concentration of MgCl 2 solution increased the total concentrations of Mg 2+ in the solution and raised the pH value of the solution, Equation (1), leading to the formation of 5-phase first through the reactions (2)(3)(4).…”

Section: Alc Value Of Common Samplesmentioning

confidence: 99%

“…It has early been concluded that the aqueous reactions between MgO and MgCl 2 in the system MgO‐MgCl 2 ‐H 2 O can yield Mg 3 (OH) 5 Cl·4H 2 O (5‐phase), Mg 2 (OH) 3 Cl·4H 2 O (3‐phase), Mg(OH) 2 , the gel and mixtures thereof, which are highly dependent on the precursor molar ratios, temperature, and MgO reactivity (ie, the reaction rate of MgO in MgCl 2 solution) 17‐23 . Besides, the equilibrium phases in the system also involve unreacted MgO and residual chlorides.…”

Section: Introductionmentioning

confidence: 99%

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Effect of alcohol leachable chloride on strength of magnesium oxychloride cement

Huang

Liu

et al. 2020

J Am Ceram Soc

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The major crystalline phases in magnesium oxychloride cement (MOC) have been extensively studied, but the other phases have not been studied due to the difficulty in identifying them. In the current study, we focused on the effect of chlorine‐containing phases other than crystalline oxychlorides on the strength of cured MOC materials. The alcohol leachable chloride (ALC) was proposed to characterize the other phases containing chlorine, and the absolute ethanol leaching test was developed to determine ACL content in a cured MOC paste. The results showed that either decreasing MgO/MgCl2 molar ratio or increasing H2O/MgCl2 molar ratio led to an increase in ALC content in cured MOC slurry, but adding a small amount of phosphoric acid resulted in very little or almost no ALC in the modified MOC slurry. In addition, increasing ALC content has been shown to significantly reduce the compressive strength of hardened MOC pastes. Thus, the modified MOC pastes had high strength, compared with the corresponding common MOC pastes. According to the experimental results, the relationship between the ALC content and the compressive strength of cured MOC materials was established. Therefore, a low ALC content was proposed as a characteristic index of high‐quality MOC materials.

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Petrographic and thermal evaluation of dolomites for the manufacture of magnesium oxychloride cement

Kacker¹,

Mehrotra²,

Rai³

1970

J. Appl. Chem.

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In the preparation of magnesium oxychloride cement from MgO and MgC12.6Ha0 solution, MgO is sometimes replaced by partially calcined dolomite, MgO.CaC0,. In this paper, the suitability of dolomites for this purpose was studied by use of petrographic, d.t.a. and X-ray diffraction techniques. It is shown that for making good oxychloride cement, the dolomite should be compact and microcrystallhe. Impurities such as siderite, haematite, magnetite and clayey matter which are generally present in dolomites, form a coating over the MgO particles during partial calcination at 750" and make the fired material less reactive and generally unsuitable for making oxychloride cement.

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A study of the system magnesium oxide-magnesium chloride-water and the heat of formation of magnesium oxychloride

Cited by 12 publications

References 7 publications

Recent development in magnesium oxychloride cement

Recent development in magnesium oxychloride cement

Effect of alcohol leachable chloride on strength of magnesium oxychloride cement

Petrographic and thermal evaluation of dolomites for the manufacture of magnesium oxychloride cement

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