Mitigation on the autogenous shrinkage of ultra-high performance concrete via using MgO expansive agent

Li, Shunkai; Mo, H. J.; Deng, Min; Cheng, Shi

doi:10.1016/j.conbuildmat.2021.125422

Cited by 49 publications

(11 citation statements)

References 46 publications

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“…In cementitious materials, pores smaller than 50 nm are closely related to autogenous shrinkage (Shah, et al, 1992). R-MEA essentially increases the sizes of pores <50 nm in the UHPC, which is beneficial in reducing its early shrinkage and is consistent with previous observations (Li et al, 2021). From Figures 10B-D, it can be seen that the porosity of the cumulative connected pores increases gradually with the increase of R-MEA doping.…”

Section: Mercury Intrusion Porosimetrysupporting

confidence: 86%

Mitigating shrinkage in ultra-high performance concrete using MgO expansion agents with different activity levels

Zhang

Li²,

Chen³

et al. 2022

Front. Mater.

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To mitigate the shrinkage properties of ultra-high performance concrete (UHPC), MgO expansion agents (MEAs) with different activity levels (R-MEA, M-MEA, and S-MEA) were prepared and incorporated into UHPC. The effect of MEA activity on the mechanical properties and volumetric stability of UHPC were evaluated by using hydration heat tests, XRD-Rietveld quantitative analysis, MIP, X-CT and SEM. The results showed that MEA addition reduces the mechanical properties of UHPC, especially at high activity levels. However, it is beneficial for compensating early shrinkage. By combining MIP and X-CT analyses, it was found that MEA effectively increases the porosity of UHPC, with R-MEA (with the strongest activity) increasing it most. The w/b ratio had a greater effect on MEA hydration than the activity level. At lower w/b ratios, R-MEA reduced autogenous shrinkage even less effectively than M-MEA. Considering both the mechanical properties and shrinkage-reducing effect, it is recommended to prepare shrinkage-reducing UHPC with a w/b ratio of 0.18 and moderately reactive M-MEA.

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Section: Mercury Intrusion Porosimetrysupporting

confidence: 86%

Mitigating shrinkage in ultra-high performance concrete using MgO expansion agents with different activity levels

Zhang

Li²,

Chen³

et al. 2022

Front. Mater.

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“…Figure 9 shows the TG/DTG curves of cement specimens mixed with MEA for 3 d and 7 d. As shown in Figure 9b,d, there are three different weight loss peaks on the DTG curve at 310-400 • C, 400-460 • C, and 650-750 • C, which correspond to the decomposition of Mg(OH) 2 , Ca(OH) 2 , and CaCO 3 , respectively. The degree of hydration of Mg(OH) 2 and MgO(H MgO) was calculated using Equations ( 2) and (3), respectively, according to the literature [33,34].…”

Section: Hydration Degree Of Mgomentioning

confidence: 99%

Effect of Working Temperature Conditions on the Autogenous Deformation of High-Performance Concrete Mixed with MgO Expansive Agent

et al. 2023

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Currently, mass concrete is increasingly utilized in various engineering projects that demand high physical properties of concrete. The water-cement ratio of mass concrete is comparatively smaller than that of the concrete used in dam engineering. However, the occurrence of severe cracking in mass concrete has been reported in numerous engineering applications. To address this issue, the incorporation of MgO expansive agent (MEA) in concrete has been widely recognized as an effective method to prevent mass concrete from cracking. In this research, three distinct temperature conditions were established based on the temperature elevation of mass concrete in practical engineering scenarios. To replicate the temperature increase under operational conditions, a device was fabricated that employed a stainless-steel barrel as the container for concrete, which was enveloped with insulation cotton for thermal insulation purposes. Three different MEA dosages were used during the pouring of concrete, and sine strain gauges were placed within the concrete to gauge the resulting strain. The hydration level of MEA was studied using thermogravimetric analysis (TG) to calculate the degree of hydration. The findings demonstrate that temperature has a significant impact on the performance of MEA; a higher temperature results in more complete hydration of MEA. The design of the three temperature conditions revealed that when the peak temperature exceeded 60 °C in two cases, the addition of 6% MEA was sufficient to fully compensate for the early shrinkage of concrete. Moreover, in instances where the peak temperature exceeded 60 °C, the impact of temperature on accelerating MEA hydration was more noticeable.

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“…However, Materials 2022, 15, 7412 2 of 22 it is unable to shrink because of surrounding elements and thus this is the most common within the initial days after casting [18]. Additionally, it is reported that the effect of several shrinkage mechanisms contributes to total shrinkage in concrete including autogenous shrinkage, chemical shrinkage, carbonation shrinkage, drying shrinkage, plastic shrinkage, and thermal shrinkage [16,[19][20][21]. Furthermore, the effect of autogenous shrinkage has a major influence on HPC and UHPC during the initial days after casting [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, it is reported that the addition of silica fume in a high-performance cementitious matrix significantly affects the mechanism of autogenous shrinkage and thus there is a need for its proper monitoring in these composite matrixes [ 29 ]. Moreover, the intrusion of 5–10% of silica fume in the matrix significantly increases the mechanism of autogenous shrinkage [ 20 ]. This is governed mainly due to the following reasons: (i) refined pore structure, (ii) improved CSH synthesis with a porous structure due to portlandite consumption, and (iii) accelerated hydration and water adsorption around silica fume particles.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Autogenous Shrinkage of Concrete Incorporating Super Absorbent Polymer and Waste Materials through Individual and Ensemble Machine Learning Approaches

Qureshi

Saleem²,

Javed

et al. 2022

Materials

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The use of superabsorbent polymers, sometimes known as SAP, is a tremendously efficacious method for reducing the amount of autogenous shrinkage (AS) that occurs in high-performance concrete. This study utilizes support vector regression (SVR) as a standalone machine-learning algorithm (MLA) which is then ensemble with boosting and bagging approaches to reduce the bias and overfitting issues. In addition, these ensemble methods are optimized with twenty sub-models with varying the nth estimators to achieve a robust R2. Moreover, modified bagging as random forest regression (RFR) is also employed to predict the AS of concrete containing supplementary cementitious materials (SCMs) and SAP. The data for modeling of AS includes water to cement ratio (W/C), water to binder ratio (W/B), cement, silica fume, fly ash, slag, the filer, metakaolin, super absorbent polymer, superplasticizer, super absorbent polymer size, curing time, and super absorbent polymer water intake. Statistical and k-fold validation is used to verify the validation of the data using MAE and RMSE. Furthermore, SHAPLEY analysis is performed on the variables to show the influential parameters. The SVM with AdaBoost and modified bagging (RF) illustrates strong models by delivering R2 of approximately 0.95 and 0.98, respectively, as compared to individual SVR models. An enhancement of 67% and 63% in the RF model, while in the case of SVR with AdaBoost, it was 47% and 36%, in RMSE and MAE of both models, respectively, when compared with the standalone SVR model. Thus, the impact of a strong learner can upsurge the efficiency of the model.

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Mitigation on the autogenous shrinkage of ultra-high performance concrete via using MgO expansive agent

Cited by 49 publications

References 46 publications

Mitigating shrinkage in ultra-high performance concrete using MgO expansion agents with different activity levels

Mitigating shrinkage in ultra-high performance concrete using MgO expansion agents with different activity levels

Effect of Working Temperature Conditions on the Autogenous Deformation of High-Performance Concrete Mixed with MgO Expansive Agent

Prediction of Autogenous Shrinkage of Concrete Incorporating Super Absorbent Polymer and Waste Materials through Individual and Ensemble Machine Learning Approaches

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