Effect of Molar Ratios on Compressive Strength of Modified Magnesium Oxysulfate Cement

Li, Zhenguo; Ji, Zesheng

doi:10.14257/ijhit.2015.8.6.09

Cited by 11 publications

(7 citation statements)

References 8 publications

(9 reference statements)

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“…Further increase of H gives accumulation of MH and gradually results in the collapse of paste structure, demonstrating the low water-resistance of MOS cement paste. Similar experimental results have been reported in [56], in which XRD results exhibits stronger peak intensity of Phase 517 and weaker peak intensity of MH when H = 20 than H = 28, indicating the decomposition of Phase 517 and generation of more MH. It is suggested that when H is around 14-16, the only equilibrium phase is Phase 517, which is favorable to the strength development for MOS cement paste.…”

Section: Influence Of Molar Ratios On Hydrated Productssupporting

confidence: 88%

“…Further increase of H gives accumulation of MH and gradually results in the collapse of paste structure, demonstrating the low water-resistance of MOS cement paste. Similar experimental results have been reported in [56], in which XRD results exhibits stronger peak intensity of Phase 517 and weaker peak intensity It can be observed that large M makes for the formation of Phase 517 and MH in Figure 4. When M is equal to 3, Phase 517 begins to appear in the MOS paste.…”

Section: Influence Of Molar Ratios On Hydrated Productssupporting

confidence: 87%

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Fractal Analysis on Pore Structure and Hydration of Magnesium Oxysulfate Cements by First Principle, Thermodynamic and Microstructure-Based Methods

Huang

et al. 2021

Fractal Fract

121

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Magnesium oxysulfate (MOS) cement is a typical eco-friendly cementitious material, which presents excellent performances. In this work, a novel multiscale modeling strategy is proposed to simulate the hydration and pore structure of MOS cement system. This work collected and evaluated the Gibbs free energy of formation for main hydrates and equilibrium constant of main reactions in MOS cement system based on a first principle calculation using Material Studio. Followingly, the equilibrium phase compositions of MOS cement system were simulated through PHREEQC to investigate the molar ratio dependence of equilibrium phase compositions. Results showed that large M (MgO/MgSO4) was beneficial for the formation of 5Mg(OH)2·MgSO4·7H2O (Phase 517) and large H (H2O/MgSO4) tended to decompose MOS cement paste and cause leaching. The microstructure-based method visualized the hydration status of MOS cement systems at initial and ultimate stages via MATLAB and the results showed that large M was significant to reduce porosity, and similar results for the case of small H. Fractal analysis confirms that fractal dimension of pore structure (Df) was significantly decreased after the hydration of MOS and was positively correlated to the porosity of the paste. In addition, it can be referred that large M and small H were beneficial for modifying the microstructure of MOS paste by decreasing the value of Df.

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Section: Influence Of Molar Ratios On Hydrated Productssupporting

confidence: 88%

“…Further increase of H gives accumulation of MH and gradually results in the collapse of paste structure, demonstrating the low water-resistance of MOS cement paste. Similar experimental results have been reported in [56], in which XRD results exhibits stronger peak intensity of Phase 517 and weaker peak intensity It can be observed that large M makes for the formation of Phase 517 and MH in Figure 4. When M is equal to 3, Phase 517 begins to appear in the MOS paste.…”

Section: Influence Of Molar Ratios On Hydrated Productssupporting

confidence: 87%

Fractal Analysis on Pore Structure and Hydration of Magnesium Oxysulfate Cements by First Principle, Thermodynamic and Microstructure-Based Methods

Huang

et al. 2021

Fractal Fract

121

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“…According to previous studies, the mechanical properties of cement depend on the phase composition, the microscopic appearance of the hydration products of the cement slurry and the raw material ratio. According to Li's report [24], the selection of the M was limited by the rheology (upper limit) and processability (lower limit) of the mixture. This section primarily studies the effects of the M on the performance of the MOCFC.…”

Section: Molar Ratio (M)mentioning

confidence: 99%

Properties of Foam Concrete Prepared From Magnesium Oxychloride Cement

Zhou¹

2020

Ceramics - Silikaty

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To broaden the application of magnesium oxychloride cement (MOC) in thermal insulation materials, lightly burned magnesia powder and magnesium chloride hexahydrate were used as the main raw materials of cement and a chemical foaming method was used to prepare a magnesium oxychloride cement foam concrete (MOCFC) with fast hardness and early strength. By changing the molar ratio (M) of the MOCFC and adding different dosages of hydrogen peroxide (H 2 O 2 ), fly ash (FA), potassium dihydrogen phosphate (KDP) and other admixtures, while measuring and observing the compressive strength and flexural strength at 3, 7, and 28 days, the thermal conductivity, dry apparent density, volume water absorption, softening coefficient, and other parameters, combined with its hydration phase composition and microscopic appearance, the effect of the molar ratio and the admixtures on the properties of MOCFC were studied. The results show that with an increase in the molar ratio and the dosage of H 2 O 2 , FA and KDP, the internal pore structure of the slurry changes significantly, which affects its mechanical properties, water resistance, and thermal insulation performance.Water absorption, Wt (% by volume) 15 16 22

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“…However, only the acid solubility and plugging ability of the MOC cement were studied. Magnesium oxysulfate (MOS) cement has low hygroscopicity, making it easier to transport and giving it a longer shelf life. , Commonly, the strength of the MOS cement is lower due to the limited solubility of MgSO 4 ·7H 2 O at ambient temperature. However, this can be effectively improved by raising temperatures or by adding modifying additives. , Cui et al studied the fundamental properties and plugging performance of the MOS cement.…”

Section: Introductionmentioning

confidence: 99%

“…Magnesium oxysulfate (MOS) cement has low hygroscopicity, making it easier to transport and giving it a longer shelf life. 25 , 26 Commonly, the strength of the MOS cement is lower due to the limited solubility of MgSO 4 ·7H 2 O at ambient temperature. However, this can be effectively improved by raising temperatures or by adding modifying additives.…”

Section: Introductionmentioning

confidence: 99%

Magnesium Oxychloride and Magnesium Oxysulfate Cements as Temporary Plugging Agents in Geothermal Drilling

Yan,

Pang,

Dong

et al. 2023

ACS Omega

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The development and utilization of geothermal resources are effective ways to alleviate the current haze situation, adjust the energy structure, and achieve energy conservation and emission reduction. Geothermal formations typically contain extensive fracture networks, with fracture openings. These fracture networks can result in substantial losses of the drilling fluid and increased costs for geothermal drilling. Temporary plugging cements are used to solve the problem of lost circulation due to their high strength and high acid solubility. In this paper, two types of temporary plugging materials, magnesium oxysulfate (MOS) cement and magnesium oxychloride (MOC) cement, were prepared. The influence of the plugging agent on the flow field and the force exerted on the solid under the action of the fluid was analyzed using fluid−solid coupling software. The simulation results show that when subjected to a flow rate of 10 m/s, the edge of the cement experiences a significant force, while the stress is not widely transmitted to the middle and rear of the cement. This indicates that the cement has a strong resistance to the fluid flow. The fundamental characteristics of MOC cement and MOS cement, such as compressive strength and setting time, were investigated. The test results show that adjusting the molar ratio of the two types of cements can shorten the setting time by 60% and increase the compressive strength to up to 23 MPa. In addition, the acid solubility of the cement with different ratios of raw materials is above 95%. The plugging performance of these two cements as loss circulation materials was evaluated by using a physical simulation device. The pressure bearing capacity of the MOC cement with different MgO/MgCl 2 •6H 2 O/H 2 O molar ratios ranged between 13.4 and 23.6 MPa. The maximum bearing capacity of the MOS cement can reach up to 18.6 MPa. The results showed that both cements possess excellent plugging and pressure bearing capacity.

show abstract

Effect of Molar Ratios on Compressive Strength of Modified Magnesium Oxysulfate Cement

Abstract: To determine the effect of molar ratios on compressive strength of magnesium oxysulfate cement (MOS)

Cited by 11 publications

References 8 publications

Fractal Analysis on Pore Structure and Hydration of Magnesium Oxysulfate Cements by First Principle, Thermodynamic and Microstructure-Based Methods

Fractal Analysis on Pore Structure and Hydration of Magnesium Oxysulfate Cements by First Principle, Thermodynamic and Microstructure-Based Methods

Properties of Foam Concrete Prepared From Magnesium Oxychloride Cement

Magnesium Oxychloride and Magnesium Oxysulfate Cements as Temporary Plugging Agents in Geothermal Drilling

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