Strength development and micro-mechanism of magnesium oxychloride cement concrete

Qiao, Huimin; Zhu, Bowu; Shi, Yan; Dong, Jinmei; Wanjiru, M. Elizabeth

doi:10.1179/1432891715z.0000000001401

Cited by 12 publications

(5 citation statements)

References 9 publications

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“…All of these properties develop in quite a short curing time, so the material is suitable for quick repairs. Further, MOC is not affected by oils, grease, or paint [8][9][10][11], and it is less alkaline (pH~10) than PC, making it appropriate for use with glass fibers and preventing the aging process as well as with other fillers and aggregates such as tire rubber, synthetic resin, and wood particles [12]. The advantage of MOC also lies in the fact that it has a high bonding capacity with different types of filers including secondary raw materials coming from industrial processes.…”

Section: Introductionmentioning

confidence: 97%

Carbon Dioxide Uptake by MOC-Based Materials

et al. 2020

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In this work, carbon dioxide uptake by magnesium oxychloride cement (MOC) based materials is described. Both thermodynamically stable magnesium oxychloride phases with stoichiometry 3Mg(OH)2∙MgCl2∙8H2O (Phase 3) and 5Mg(OH)2∙MgCl2∙8H2O (Phase 5) were prepared. X-ray diffraction (XRD) measurements were performed to confirm the purity of the studied phases after 7, 50, 100, 150, 200, and 250 days. Due to carbonation, chlorartinite was formed on the surface of the examined samples. The Rietveld analysis was performed to calculate the phase composition and evaluate the kinetics of carbonation. The SEM micrographs of the sample surfaces were compared with those of the bulk to prove XRD results. Both MOC phases exhibited fast mineral carbonation and high maximum theoretical values of CO2 uptake capacity. The materials based on MOC cement can thus find use in applications where a higher concentration of CO2 in the environment is expected (e.g., in flooring systems and wall panels), where they can partially mitigate the harmful effects of CO2 on indoor air quality and contribute to the sustainability of the construction industry by means of reducing the carbon footprints of alternative building materials and reducing CO2 concentrations in the environment overall.

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Section: Introductionmentioning

confidence: 97%

Carbon Dioxide Uptake by MOC-Based Materials

et al. 2020

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“…This is in line with the findings of Sun and Qiao. that MOC develops rapidly and with high strength in the early stages and grows slowly in the later stages 27 , 31 . Therefore, the MOC-stabilized crushed stone material must use the 28-day curing age unconfined compressive strength as its final strength.…”

Section: Design Of Mixed Materials Composition Based On Response Surf...mentioning

confidence: 92%

“…For the mixed-material design of inorganic binder-stabilized materials, the "Technical Guidelines for Construction of Highway Roadbases" (JTG/T F20-2015) stipulates a 7D unconfined compressive strength as the control indicator. However, existing studies have reported that MOC-stabilized materials exhibit characteristics of rapid early strength growth, high proportions, and poor water resistance [31][32][33][34][35][36] . The suitable material ratio for the actual pavement base requirements may not be accurately determined by directly applying this indicator, and its water resistance cannot be considered.…”

Section: Determination Of Control Indicators For Mixed Materials Comp...mentioning

confidence: 99%

Mixture composition design of magnesium oxychloride cement-stabilized crushed stone materials applied as a pavement base

Zhang,

Luo,

Sun

2024

Sci Rep

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Conventional binding materials, such as silicate cement and lime, present high energy consumption, pollution, and carbon emissions. Therefore, we utilize crushed stone as a stabilization material. Magnesium oxychloride cement (MOC) is modified and used as an inorganic admixture owing to its eco-friendly nature and low carbon content. We analysed the control indicators of an integrated design of MOC-stabilized crushed stone by conducting unconfined compressive strength and water-resistance tests. The optimum mixing composition of the MOC-stabilized crushed stone was determined through the response surface methodology. We determined the best approach and dosage for improving the water resistance of MOC-stabilized crushed stone by comparing the effects of four modification methods: fly ash, citric acid + silica fume, phosphoric acid + waterborne polyurethane, and dihydrogen phosphate potassium salt. We also perform a comparison with 5% ordinary silicate cement-stabilized crushed stone. The results indicate that the MOC-stabilized crushed stone exhibits a rapid increase in strength in the early stage, but this rate reduces after 28 days. The mixing design employs the 4-day unconfined compressive strength and 1-day water resistance coefficient as the technical indicators. The best mixing composition includes a 4.27% MOC dosage and a molar ratio of MgO/MgCl2 of 5.85. We use 1% citric acid + 10% silica fume in equal amounts to replace the MOC dopant method for composite modification of the MOC stabilized crushed stone. Consequently, the 1-day water resistance coefficient before water immersion is significantly increased from 0.78 to 0.91 and its 4-day unconfined compressive strength is only reduced by 0.10 MPa. This significantly improves the water resistance of the MOC-stabilized crushed stone and ensures that its strength remains unaffected, which is the optimal modification method. However, this method must ensure that a small amount of citric acid and silica fume are uniformly distributed in the MOC-stabilized crushed stone, which increases the construction difficulty of the road base.

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“…Qiao et al [76] substituted MgO with GGBFS to develop an MOC cement-based composite and revealed mostly promising findings regarding the development of compressive strength. The compressive strength increased progressively over time, reaching approximately 48 MPa at 1 d of curing, followed by 51 MPa and 57 MPa, respectively, at 14 d and 28 d curing age.…”

Section: Effect Of Ggbfs On Mocmentioning

confidence: 99%

Magnesium Oxychloride Cement: Development, Opportunities and Challenges

Ahmad,

Rawat,

Zhang

2024

Applied Sciences

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Magnesium oxychloride cement (MOC), an alternative to ordinary Portland cement (OPC), has attracted increasing research interest for its excellent mechanical properties and its green and sustainable attributes. The poor water resistance of MOC limited its usage mainly to indoor applications; nevertheless, recent advances in water-resistant MOC have expanded the material’s potential applications from indoor to outdoor. This review aims to showcase recent advances in MOC, including water-resistant MOC and ductile fiber-reinforced MOC (FRMOC), exploring their potential applications including in sustainable construction for future generations. The mechanism under different curing procedures such as normal and CO2 curing and the effect of different inorganic and organic additives on the water resistance of MOC composites are discussed. In particular, the review highlights the recent developments in achieving over 100% strength retention under water at 28 days as well as advancements in FRMOC, where tensile strength has surpassed 10 MPa with a remarkable strain capacity ranging from 4–8%. This paper also sheds light on the potential applications of MOC as a fire-resistant coating material, green-wood-MOC composite building material, and in reducing solid waste industrial byproduct accumulations. Finally, this study suggests future research directions to enhance the practical application of MOC.

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Strength development and micro-mechanism of magnesium oxychloride cement concrete

Cited by 12 publications

References 9 publications

Carbon Dioxide Uptake by MOC-Based Materials

Carbon Dioxide Uptake by MOC-Based Materials

Mixture composition design of magnesium oxychloride cement-stabilized crushed stone materials applied as a pavement base

Magnesium Oxychloride Cement: Development, Opportunities and Challenges

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