Combined impact of silicate-amorphicity and MgO-reactivity on the performance of Mg-silicate cement

Abdel‐Gawwad, Hamdy A.; El-Aleem, S. Abd; Amer, Atef M.; El-Didamony, H.; Arif, Mohamed A.

doi:10.1016/j.conbuildmat.2018.08.171

Cited by 59 publications

(8 citation statements)

References 37 publications

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“…With progress in hydration, the band is clearly visible in SF mixes at 28 days confirming the formation of M-S-H. The intense bands in the region of ∼1250 to 1000 cm −1 are associated with Si-O-Si vibrations (Brew and Glasser, 2005;Tonelli et al, 2016;Abdel-Gawwad et al, 2018). The Si-O-Si internal vibrations linked to unreacted silica are generally centered at the higher end of the band.…”

Section: Ftir Analysismentioning

confidence: 74%

“…The SF mixes at 7 days displayed peaks centered at ∼1100 cm −1 , which are a result of the lower reactivity of the SF to form M-S-H. At 28 days, the peak for SF mixes aligns with RS mixes indicating formation of M-S-H. The disappearance of the peak at ∼800 cm −1 associated with Si-O-Si internal vibrations of unreacted silica from 7 to 28 days for SF mixes confirms conversion to M-S-H (Abdel- Gawwad et al, 2018;Bhagath Singh et al, 2020). Similar changes corresponding to the peak shift on continued hydration have been reported for MgO-SiO 2 binder system (Brew and Glasser, 2005;Bhagath Singh et al, 2020).…”

Section: Ftir Analysismentioning

confidence: 82%

“…The structural form of the two are somewhat different with C-S-H typically having a dreierketten structure whereas M-S-H has a layered silicate structure similar to clay minerals (Bernard et al, 2017). The specific characteristics of the M-S-H is affected by the physical and chemical properties of the constituent raw materials (MgO and SiO 2 ), mix design and curing conditions (Jia et al, 2017;Tran and Scott, 2017;Abdel-Gawwad et al, 2018;Li et al, 2018;Sonat and Unluer, 2019;Dhakal et al, 2021;Shah and Scott, 2021b). MgO-SiO 2 binders have shown potential for applications in: waste immobilization/encapsulation where a lower pH (< 10.5) environment is required; as refractory castables because of high melting temperature; and as building materials due to excellent mechanical properties (Zhang et al, 2012, Zhang et al, 2014Walling et al, 2015;Walling and Provis, 2016;Tran and Scott, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Use Of Olivine For The Production Of MgO-SiO2 Binders

Nye

Shah

Oze

et al. 2021

Front. Built Environ.

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The potential for using MgO and SiO2, recovered from olivine, was investigated for use as a cementitious binder system. The MgO to SiO2 proportion for the binder was fixed at 1:1. The nature of the hydration products were characterized using a variety of techniques including isothermal calorimetry, XRD, FTIR, and SEM. The primary binding component of the paste was determined to be magnesium silicate hydrate (M-S-H). The recovered silica exhibited faster reactivity compared to commercially available silica fume. Compressive strengths in excess of 20 MPa were obtained using the materials recovered from olivine.

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Section: Ftir Analysismentioning

confidence: 74%

Section: Ftir Analysismentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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Use Of Olivine For The Production Of MgO-SiO2 Binders

Nye

Shah

Oze

et al. 2021

Front. Built Environ.

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“…1,2 The rate of formation and the properties of M-S-H formed are influenced by various parameters such as the reactivity of MgO, source of SiO 2 , initial MgO/ SiO 2 ratio, and curing conditions. [3][4][5][6][7][8][9] A wide range of studies have looked at the potential of using M-S-H for different applications including, encapsulation of trace metal contaminants in waste, refractory castables, building materials, and off-Earth construction. [10][11][12] M-S-H binders offer an exciting prospect from an environmental standpoint for the cement industry, which accounts for ~7% of global CO 2 emissions.…”

Section: Introductionmentioning

confidence: 99%

“…13 Unlike portland cement (PC), which requires a temperature of 1400-1500℃ for its production, MgO is typically obtained from the calcination of magnesite (MgCO 3 ) at a lower temperature (700-800℃), resulting in potential energy savings. 5,14 A further reduction in energy savings and reduction in CO 2 emission is possible if MgO could be efficiently extracted from the widely available magnesium silicate minerals. 1,15,16 Studies have shown that M-S-H binders could exhibit excellent mechanical properties with compressive strength in excess of 50 MPa, 6,17 although limited information is available on the pore structural features of the M-S-H binder system.…”

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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Effect of fly ash on mechanical properties of magnesium oxychloride cement under water attack

Guo

Zhang

Soe³

et al. 2019

Structural Concrete

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As an eco‐friendly construction material, magnesium oxychloride cement (MOC) has attracted much research interest in recent decades, however, its mechanical properties degrade severely under water attack, which has prevented its wide application in engineering structures. As a widely used mineral waste, fly ash has been applied in civil engineering for decades. The active SiO2 in fly ash is considered to be conductive to improve the water resistance of MOC. In this paper, the influence of fly ash on the mechanical properties of MOC is investigated, especially when subject to water attack. First, the basic mix design of the MOC with a suitable combination of the molar ratios of MgO/MgCl2 and H2O/MgCl2 is developed, and the developed basic MOC mix is modified by adding fly ash to improve its water resistance. Second, the physical and mechanical properties of both the basic MOC and the fly ash modified MOC, such as compressive strength, Young's modulus, flexural strength cured at room temperature, and immersed in water for 28 days at room temperature (25°C) are determined. It is found that the incorporation of fly ash decreases the workability or fluidity, retards the setting time, but improves the compressive strength and water resistance of the MOC. The techniques of X‐ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis/differential scanning calorimetry, scanning electron microscopy, and mercury intrusion porosimetry are applied to the MOC specimens to discover the mechanism by which fly ash affects on the water resistance of MOC. The microscale analysis shows that the addition of fly ash optimizes the pore distribution in MOC resulting in a denser structure, which contributes to the water repellence.

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Combined impact of silicate-amorphicity and MgO-reactivity on the performance of Mg-silicate cement

Cited by 59 publications

References 37 publications

Use Of Olivine For The Production Of MgO-SiO2 Binders

Use Of Olivine For The Production Of MgO-SiO2 Binders

Pore structure characteristics of MgO–SiO₂binder

Effect of fly ash on mechanical properties of magnesium oxychloride cement under water attack

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Combined impact of silicate-amorphicity and MgO-reactivity on the performance of Mg-silicate cement

Cited by 59 publications

References 37 publications

Use Of Olivine For The Production Of MgO-SiO2 Binders

Use Of Olivine For The Production Of MgO-SiO2 Binders

Pore structure characteristics of MgO–SiO2binder

Effect of fly ash on mechanical properties of magnesium oxychloride cement under water attack

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Product

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Pore structure characteristics of MgO–SiO₂binder