Factors analysis on autogenous volume deformation of MgO concrete and early thermal cracking evaluation

Chen, Xia; Yang, Hua-Qian; Li, Wenwei

doi:10.1016/j.conbuildmat.2016.02.093

Cited by 39 publications

(16 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Generally, several strategies are utilized to control temperature and prevent cracks in practical engineering, including the adoption of pre-cooling aggregate and ice water, a pipe cooling method by circulating cold water through internal pipes during the concrete hardening stage [11], and the usage of a certain dosage of fly ash [12][13][14][15], fibers [16][17][18][19][20][21][22][23], and a magnesia expansion agent (abbreviated as MgO thereafter) [24][25][26][27][28][29][30]. However, the pre-cooling method and pipe cooling method need some additional labor as well as more construction time and cost [11].…”

Section: Introductionmentioning

confidence: 99%

“…MgO, which is manufactured by calcining magnesite or any other magnesium ore, is reported to be used in mass concrete of dozens of dams in the past few decades to minimize or eliminate the expensive temperature control measures in dam construction [27,31]. This is because the reaction of MgO tends to produce a certain volume expansion that could compensate part of or all of the shrinkage of concrete [25][26][27][28], which could consequently lower the cracking risks of structure [24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of MgO on the Hydration and Shrinkage Behavior of Low Heat Portland Cement-Based Materials via Pore Structural and Fractal Analysis

Wang

Liu

et al. 2022

Fractal Fract

View full text Add to dashboard Cite

Currently, low heat Portland (LHP) cement is widely used in mass concrete structures. The magnesia expansion agent (MgO) can be adopted to reduce the shrinkage of conventional Portland cement-based materials, but very few studies can be found that investigate the influence of MgO on the properties of LHP cement-based materials. In this study, the influences of two types of MgO on the hydration, as well as the shrinkage behavior of LHP cement-based materials, were studied via pore structural and fractal analysis. The results indicate: (1) The addition of reactive MgO (with a reactivity of 50 s and shortened as M50 thereafter) not only extends the induction stage of LHP cement by about 1–2 h, but also slightly increases the hydration heat. In contrast, the addition of weak reactive MgO (with a reactivity of 300 s and shortened as M300 thereafter) could not prolong the induction stage of LHP cement. (2) The addition of 4 wt.%–8 wt.% MgO (by weight of binder) lowers the mechanical property of LHP concrete. Higher dosages of MgO and stronger reactivity lead to a larger reduction in mechanical properties at all of the hydration times studied. M300 favors the strength improvement of LHP concrete at later ages. (3) M50 effectively compensates the shrinkage of LHP concrete at a much earlier time than M300, whereas M300 compensates the long-term shrinkage more effectively than M50. Thus, M300 with an optimal dosage of 8 wt.% is suggested to be applied in mass LHP concrete structures. (4) The addition of M50 obviously refines the pore structures of LHP concrete at 7 days, whereas M300 starts to refine the pore structure at around 60 days. At 360 days, the concretes containing M300 exhibits much finer pore structures than those containing M50. (5) Fractal dimension is closely correlated with the pore structure of LHP concrete. Both pore structure and fractal dimension exhibit weak (or no) correlations with shrinkage of LHP concrete.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of MgO on the Hydration and Shrinkage Behavior of Low Heat Portland Cement-Based Materials via Pore Structural and Fractal Analysis

Wang

Liu

et al. 2022

Fractal Fract

View full text Add to dashboard Cite

show abstract

“…[13,14]. Due to the action of the expansive agent, the volume of grout will expand during the hydration process [15,16]; the constrained stress generated by the volume expansion of the grout causes the fractured rock masses in the grouting area to squeeze together, and then a complete stone mass is formed under the bonding action of the expansive grout, resulting in a "squeezing before bonding" grouting reinforcement effect, which improves the overall reinforcement strength [14,17,18].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Strength Enhancement of Expansive Grout

Wang

Yao

et al. 2022

Materials

View full text Add to dashboard Cite

Adding an expansive agent to ordinary grout can cause an expansion in volume, but also reduces its strength. In order to improve the strength of expansive grout, quartz sand is used as the strength enhancement additive. In this study, the expansion behavior and mechanical properties of the expansive grout with quartz sand are explored, through expansion development monitoring, uniaxial compression strength (UCS), acoustic emission (AE), SEM and XRD test methods. The results showed that: (1) The final expansion ratio and expansion development of the samples are related to the use of an expansive agent, but not affected by quartz sand. With the increase in expansion agent content, the average expansion ratios of the samples are 0.03%, 0.16%, 0.67%, 1.06% and 1.48%; (2) The UCS of the samples decreases with the increase in expansive agent content but increases with the increase in quartz sand content. Compared with no quartz sand, and with the increase in quartz sand content, the average strength of the samples increased by 10.51%, 29.88%, and 37.92%; (3) Quartz sand does not effectively participate in the hydration reaction, but it can effectively enhance the strength of the expansive grout without affecting its volume expansion, which makes it an ideal expansive grout strength enhancement additive.

show abstract

“…In order to restrain concrete cracking and enhance its durability, researchers have proposed three methods. One is to compensate for shrinkage of cement-based materials during hydration by adding expansion agents, such as CaO-type, MgO-type, and AFt-type expansion agents, which can reduce shrinkage cracks [1,2,3,4,5]. The other is to improve the crack resistance of concrete by adding fibers, such as polypropylene (PP) fibers, polyvinyl alcohol (PVA) fibers, and steel fibers, which can reduce plastic cracks and improve the ductility of concrete [6,7,8,9].…”

Section: Introductionmentioning

confidence: 99%

Deformation and Compressive Strength of Steel Fiber Reinforced MgO Concrete

Jiang

Mao²,

Deng³

et al. 2019

Materials

View full text Add to dashboard Cite

To reduce the cracking caused by shrinkage and avoid the brittle behavior of concrete, MgO expansion agent and steel fibers were used in this paper. Firstly, the effect of MgO and steel fibers on the compressive strength of concrete was compared. The results showed that the compressive strength of steel fibers reinforced concrete (SC) and steel fiber reinforced MgO concrete (SMC) was significantly improved. Compared with ordinary concrete (OC), SMC’s 28 days compressive strength increased by 19.8%. Secondly, the influence of MgO and steel fibers with different contents on the self-volumetric deformation of concrete was compared through the experiment. The results showed that as a result of the hydration expansion of MgO, MC and SMC both showed obvious expansion, and their 190 days expansion was 335 με and 288 με, respectively. Lastly, through a scanning electron microscope (SEM) test, it was found that the constraint effect of steel fibers changed the expansion mode of MgO from outward expansion to inward extrusion, thus improving the interfacial bond strength of concrete.

show abstract

Factors analysis on autogenous volume deformation of MgO concrete and early thermal cracking evaluation

Cited by 39 publications

References 6 publications

Influence of MgO on the Hydration and Shrinkage Behavior of Low Heat Portland Cement-Based Materials via Pore Structural and Fractal Analysis

Influence of MgO on the Hydration and Shrinkage Behavior of Low Heat Portland Cement-Based Materials via Pore Structural and Fractal Analysis

Experimental Study on Strength Enhancement of Expansive Grout

Deformation and Compressive Strength of Steel Fiber Reinforced MgO Concrete

Contact Info

Product

Resources

About