Expansion Mechanism and Properties of Magnesium Oxide Expansive Hydraulic Cement for Engineering Applications

Li, Siqi; Feng, Yecheng; Yang, Jinmeng

doi:10.1155/2021/5542072

Cited by 8 publications

(5 citation statements)

References 65 publications

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“…The primary limitation of this construction method is that the induction of preloading stress is contingent upon the expansion rate and the interstitial distance of the expansive strengthening band. The expansion rate of the concrete within the expansive strengthening band is capped at 0.8% (Li et al, 2021). If the expansion rate surpasses this threshold, the alterations in porosity induced by expansion can compromise the mechanical attributes and longevity of the concrete.…”

Section: Introductionmentioning

confidence: 99%

Investigation into the seamless construction for hundred-meter scale super-length raft structure based on magnesia expansive agent concrete

Han,

Wang,

Liao

et al. 2024

Front. Mater.

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This research introduces an innovative construction method based on magnesia expansive agent concrete for the seamless construction of hundred-meter scale super-length raft structures, corroborated by the on-site test. The basic principle of this construction method is to use the pre compression stress generated by magnesia expansive agent to offset temperature and shrinkage stress. A temperature-strain monitoring system was employed to gather data, affirming the technique’s applicability and safety. Through the examination of temperature and strain dispersion trends in super-length raft structure, recommendations for the configuration of temperature-strain sensors have been put forth. Through the scrutiny of the temporal evolution pattern of temperature, the specific temporal and spatial coordinates that warrant particular vigilance during the surveillance of the raft’s inner-surface temperature difference were identified. Upon evaluating the correlation between strain dispersion and strain-temperature differential in the raft’s thickness dimension, a novel temperature control index (the bottom-surface temperature difference) was introduced. The threshold for this metric was established at 30°C, derived from empirical test outcomes conducted on-site. Furthermore, the critical regions for monitoring the bottom-surface temperature difference were specified.

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Section: Introductionmentioning

confidence: 99%

Investigation into the seamless construction for hundred-meter scale super-length raft structure based on magnesia expansive agent concrete

Han,

Wang,

Liao

et al. 2024

Front. Mater.

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“…Meanwhile, the shrinkage reduction effect is more economical and effective than that of traditional additives. Therefore, MgO is commonly used in practical civil engineering [ 1 , 2 ]. Due to the large volume of hydration products (Mg(OH) 2 ), the shrinkage of the materials can be reduced [ 3 , 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

The Influence of CaO and MgO on the Mechanical Properties of Alkali-Activated Blast Furnace Slag Powder

et al. 2022

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CaO and MgO are both reported as effective activators for blast furnace slag. However, the synergistic effect of these two components on the mechanical properties of alkali-activated blast furnace slag remains unclear. In this study, the flexural and compressive strengths of alkali-activated blast furnace slag powder with MgO and CaO range from 0% to 30% by the mass ratio of alkali-activated blast furnace slag powder are investigated. Moreover, the dry shrinkage rate of alkali-activated blast furnace slag powder is measured. One percent refractory fibers by volume of binder materials are added in the alkali-activated blast furnace slag. Some refractory fibers are treated with water flushing, meanwhile, some refractory fibers are directly used without any treatment. Finally, the scanning electron microscope, the thermogravimetric analysis curves and the XRD diffraction spectrums are obtained to reflect the inner mechanism of the alkali-activated blast furnace slag powder’s mechanical properties. The water-binder ratios of the alkali-activated blast furnace slag powder are 0.35 and 0.42. The curing ages are 3 d, 7 d and 28 d. The measuring temperature for the specimens ranges from 20 °C to 800 °C. Results show that the flexural and compressive strengths increase with the increased curing age, the decreased water-binder ratio and the addition of refractory fibers. The water-treated refractory fibers can improve the mechanical strengths. The mechanical strengths increase in the form of a quadratic function with the mass ratio of MgO and CaO, when the curing age is 3 d, the increasing effect is the most obvious. A higher water-binder ratio leads to an increasing the drying shrinkage rate. The activated blast furnace slag powder with CaO shows a higher drying shrinkage rate. The mechanical strengths decrease with the increasing testing temperature.

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“…[9]. BFS and FA are common industrial wastes in our daily life, showing high production and wide distribution [11]. A large amount of BFS and FA have polluted the atmosphere, causing smog.…”

Section: Introductionmentioning

confidence: 99%

The Influence of CO2 Curing on the Mechanical Performance and the Corresponding Chloride Ion Resistance of Alkali-Activated Compound Mineral Admixtures

et al. 2022

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In this paper, the mechanical properties (the flexural strength, compressive strength and the drying shrinkage rate) of CO2-cured alkali-activated compound mineral admixtures (blast furnace slag powder (BFS) and fly ash (FA)) are investigated. In addition, the corresponding chloride ion mobility coefficient is measured. Additionally, the freeze–thaw cycles with an NaCl concentration of 3% is studied. Thermogravimetric analysis and scanning electron microscopy are applied in analyzing the mechanical properties. The curing ages of the alkali-activated compound mineral admixtures are 1 day, 3 days and 28 days. Results show that the mechanical strengths are decreased by the addition of FA and increased by the increasing curing age and CO2 curing. The maximum reducing rates of flexural and compressive strengths by FA are 47.6% and 42.3%. Meanwhile, the corresponding increasing rates by CO2 curing are 26.5% and 23.1%, respectively. The improving effect of alkali-activated BFS by CO2 curing is higher than that of FA. Furthermore, the drying shrinkage rate is increased by the increasing dosages of BFS, the increasing curing ages and CO2 curing. Additionally, CO2 curing and the increasing dosage of BFS leads to decreasing the chloride ion mobility coefficient. Finally, CO2 curing and the addition of BFS can effectively improve the resistance of NaCl freeze–thaw cycles. The compactness of the hydration products is improved by the addition of BFS and the roughness of hydration products is increased by CO2 curing.

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Expansion Mechanism and Properties of Magnesium Oxide Expansive Hydraulic Cement for Engineering Applications

Cited by 8 publications

References 65 publications

Investigation into the seamless construction for hundred-meter scale super-length raft structure based on magnesia expansive agent concrete

Investigation into the seamless construction for hundred-meter scale super-length raft structure based on magnesia expansive agent concrete

The Influence of CaO and MgO on the Mechanical Properties of Alkali-Activated Blast Furnace Slag Powder

The Influence of CO2 Curing on the Mechanical Performance and the Corresponding Chloride Ion Resistance of Alkali-Activated Compound Mineral Admixtures

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