Research on the preparation and properties of MgO expansive agent

Li, F.X.; Chen, Y.Z.; Long, S. Z.; Wang, B.; Li, G.G.

doi:10.1680/adcr.2008.22.1.37

Cited by 9 publications

(4 citation statements)

References 11 publications

(8 reference statements)

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“…Much higher curing and service temperature and pressure, coupled with more stringent technical requirements such as avoidance of micro-annuli and good bonding strength at cementing interfaces lays the prominent distinguishments of applying the cementitious materials downhole from the civil construction above the ground. Enlightened by the hydration expansion property of magnesia (Thomas J. et al, 2014;Mo et al, 2015;Ye et al, 2015;Temiz et al, 2015;Sherir et al, 2016;Jafariesfad et al, 2016;Qureshi et al, 2016;Sherir et al, 2017;Cao et al, 2018b,a;Srivastava et al, 2018;José et al, 2020;Li et al, 2010;Mo and Al-Tabbaa, 2020) and successful bulk shrinkage prevention case of Baishan dam construction (Mo et al, 2014), incorporating magnesia into Portland cement to address/mitigate its shrinkage issue arouses people's interest rather than simply categorizing magnesia as the detrimental role for the unsoundness of Portland cement application.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Magnesia Blended Cement Studies for Geotechnical Well Construction—A Review

et al. 2021

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The current paper presents a literature review on the studies of incorporation of magnesia (magnesium oxide) into Portland cement material from the geotechnical well construction perspective. Starting with a comparison of application conditions between civil construction and geotechnical well cementing, this work reviewed the Portland cement categorizations, magnesia manufacturing routes at first. Then, the physical-chemical-mechanical properties were investigated which includes the reactivity of magnesia, expansion influence from its hydration, and carbonation/dehydroxylation of magnesia blended Portland cement. The development of cement material hydration modeling methods is also summarized. Moreover, the experimental characterization methods have also been elucidated including composition determination, particle size analysis, volumetric variation measurement, compressive strength testing, shear-bond strength testing, transition state analysis, etc. Meanwhile, the results and conclusions were extracted from the literature. Through this route, a comprehensive understanding of the scientific research progress on magnesia blended Portland cement development for geotechnical well construction is derived. Additionally, it is concluded that incorporating magnesia into Portland cement can provide benefits for this material utilization in geotechnical well constructions provided the reasonable tuning among the characteristics of magnesia, the downhole surrounding conditions, and the formulation of the cement slurry. Satisfying these pre-conditions, the effective expansion not only mitigates the micro-annulus issues but also increases the shear bonding strength at the cementing interfaces. Moreover, the caustic magnesia introduction into Portland cement has the potential advantage on carbon dioxide geological sequestration well integrity compared with the Portland cement sheath without it because of the denser in-situ porous matrix evolvement and more stable carbon fixation features of magnesium carbonate. However, since the impact of magnesia on Portland cement strongly depended on its properties (calcination conditions, particle size, reactivity) and the aging conditions (downhole temperature, pressure, contacting medium), it should be noted that some extended research is worth conducting in the future such as the synchronized hydration between magnesia and Portland cement, the dosage limit of caustic magnesia in Portland cement in terms of CO2 sequestration and the corresponding mechanical properties analysis, and the hybrid method (caustic magnesia, Portland cement, and other supplementary cementitious materials) targeting the co-existence of the geothermal environment and the corrosive medium scenario.

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Section: Introductionmentioning

confidence: 99%

Recent Advances in Magnesia Blended Cement Studies for Geotechnical Well Construction—A Review

et al. 2021

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“…To this end, scientists and technicians have carried out fruitful research on the causes of cracks, cracking mechanisms, anti-cracking measures, and evaluation of anti-cracking effect from the aspects of raw materials, mix proportion, structural design, construction methods, and service environment (Nagataki and Gomi, 1998;Wang et al, 2021a;Kabir and Hooton, 2020;Chen et al, 2011b;Li and Burrows, 2013;Qureshi et al, 2018;Qureshi et al, 2019;Wang et al, 2020b;Wang et al, 2021b). In particular, scientific and technical personnel have conducted a large number of pioneering creative studies on the performance and production of magnesium oxide expansion agent (MgO) used in cement mortar and concrete (Liu et al, 1991;Gao et al, 2008;Li et al, 2010;Cao et al, 2018b), the performance of cement-based materials containing MgO (Li 1999a;Chen et al, 2010;Lu et al, 2011;Sherir et al, 2016;Sherir et al, 2017;Chen et al, 2017a;Liu et al, 2019;Wang et al, 2020a;Cao and Yan, 2019), and the expansion mechanism of MgO mortar and concrete (Mehta and Pirtz, 1980;Chatterji 1995;Deng et al, 1990;Cao et al, 2018b). The results show that MgO concrete, which is formed by mixing MgO expansion agent with concrete, can produce excellent delayed micro-expansion deformation.…”

Section: Introductionmentioning

confidence: 99%

Influence of Specimen Size on Autogenous Volume Deformation of Long-Aged MgO-Admixed Concrete

et al. 2021

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The transformation law of autogenous volume deformation of MgO-admixed concrete with specimen size was revealed through continuous observation on standard-size (Φ200 mm × 500 mm), medium-size (Φ250 mm × 500 mm), and large-size specimens (Φ250 mm × 600 mm) over 6 years. Besides, the pore parameters of concrete core samples obtained from autogenous volume deformation specimens in the 1st, 3rd, and 6th years of age were investigated. The results show that the autogenous volume deformation of MgO-admixed concrete increases with the increase in the MgO content or age. The expansion rate of the concrete specimen decreases after the age of 360 days, and the autogenous volume expansion deformation of the specimen tends to be stable after about 2 years. When the size of the specimen changes, the autogenous volume deformation of MgO-admixed concrete decreases with the increase of specimen size. During the age of 2–6 years, the expansion of medium- and large-size specimens is reduced by 6–10 and 15–20%, respectively, compared with the standard-size specimens under the same MgO content. With the condition of an appropriate MgO content, regardless of the size of the specimen, the pore structure of the concrete becomes better and better with the growth of age, the concrete becomes denser and denser, and the expansion caused by MgO hydration will not cause damage to concrete structures.

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“…We can improve the processing of cement at the clinkering stage by a better scientific understanding of the action of grinding aids (Assaad et al, 2010). We can also modify the properties of cement matrices in a number of ways: by controlling dimensional stability (Li et al, 2010), by adding fibres which strengthen the cement matrix (Park et al, 2010) and by achieving a better understanding of the pore structures in hardened cement (Zhang et al, 2010).…”

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confidence: 99%

Editorial

Glasser¹

2010

Advances in Cement Research

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Research on the preparation and properties of MgO expansive agent

Cited by 9 publications

References 11 publications

Recent Advances in Magnesia Blended Cement Studies for Geotechnical Well Construction—A Review

Recent Advances in Magnesia Blended Cement Studies for Geotechnical Well Construction—A Review

Influence of Specimen Size on Autogenous Volume Deformation of Long-Aged MgO-Admixed Concrete

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