Effect of Fly Ash and Slag Powder on Coefficient of Thermal Expansion of Concrete

Gao, Guohua; Qian, Chunxiang; Wang, Yong Wei

doi:10.4028/www.scientific.net/amr.374-377.1230

Cited by 4 publications

(3 citation statements)

References 5 publications

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“…The measurement results in Table 5 show that the thermal expansion coefficient initially increases and then decreases with the increase of MEA doping rate. According to the research conducted by Gui Bo Gao [ 40 ] and other teams, it is known that the coefficient of thermal expansion is related to the density of the material, and materials with a compact and dense structure tend to have higher coefficients of thermal expansion. In mixtures with lower initial content, the delayed hydration property of MgO contributes to filling the cracks in the cement particles, resulting in a denser cement structure and improving the coefficient of thermal expansion to some extent.…”

Section: Resultsmentioning

confidence: 99%

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Research on the Early-Age Cracking of Concrete Added with Magnesium Oxide under a Temperature Stress Test Machine

Li,

Chen,

et al. 2023

Materials

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Concrete cracking is a significant issue in the global construction industry, and the restraint stress of concrete is a crucial contributing factor to early concrete cracking. The addition of magnesium oxide additive (MEA) to concrete is a method to enhance its crack resistance. In this paper, concrete specimens with four different contents of MEA were tested with a temperature stress testing machine. The deformation characteristics and mechanical properties of concrete with varying contents of MEA were investigated using both free deformation tests and fully constrained deformation tests. The prediction model for the early restrained stress of concrete was developed by integrating the stress relaxation phenomenon of concrete with models for autogenous shrinkage, temperature deformation, and elastic modulus. According to the results, (1) the thermal expansion coefficient exhibits a pattern of initially increasing and subsequently decreasing with the increasing ratio of MEA; (2) the addition of 3% and 8% MEA can offset 23% and 35.1% of the concrete’s self-shrinkage, respectively. Nevertheless, when the added MEA content is 5%, the self-shrinkage of concrete increases by 6%; (3) the addition of 3–8% MEA can result in a 0.5–1.67 times increase in the maximum expansion stress of concrete, as well as a 0.5–0.95 times increase in cracking stress; (4) as the MEA content continues to increase, the stress relaxation level of concrete also increases. In comparison to concrete mixed without MEA, the maximum increase in the stress relaxation level of concrete is 65.5%, thereby enhancing the concrete’s anti-cracking ability. However, when the MEA dosage reaches a certain threshold, the stress relaxation enhancement brought about by the addition of MEA will no longer be significant; (5) when compared to the experimental data, the established model of early-age constraint stress accurately predicts the tensile constraint stress of concrete.

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Section: Resultsmentioning

confidence: 99%

“…The measurement results in Table 5 show that the thermal expansion coefficient initially increases and then decreases with the increase of MEA doping rate.. According to the research conducted by Gui Bo Gao [40] and other teams, it is known that the coefficient of thermal…”

Section: Effect Of Mea On the Expansion Coefficient Of Concretementioning

confidence: 96%

Research on the Early-Age Cracking of Concrete Added with Magnesium Oxide under a Temperature Stress Test Machine

Li,

Chen,

et al. 2023

Materials

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“…On the other hand, when increasing the porosity in the paste containing fly ash and slag, they observed reduced CTE of the paste, while increasing porosity in the paste containing silica fume increased the CTE. Moreover, Gao et al [28] added fly ash to concrete and concluded that it caused a significant decline in CTE. However, the addition of the slag resulted in growth at an early age.…”

Section: Introductionmentioning

confidence: 99%

Modeling Concrete Thermal Expansion Based on the Packing Density Theory

2021

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In this study, the effects of supplementary cementitious materials with changes in the structure of the concrete pores have been examined on the coefficient of thermal expansion (CTE) at different ages. The results indicated a descending trend for the CTE of the reference concrete up to 60 days (diminishing by about 12%), after which it remained constant. In contrast, an opposite trend was observed for the slagcontaining concrete, i.e., the descending trend started after 60 days, and its CTE declined by 10% up to 120 days. In the following, two equations are presented for the concrete to estimate the CTE of the concrete during its lifetime based on its CTE at the age of seven days. Across all the concretes, the reduction of CTE was associated with lowered porosity. Moreover, evaluating the distribution of the pore size showed that when the pore diameter decreased, the CTE decreased as well, indicating a strong relationship between the median diameter of the pores and the CTE. Considering the fact that the concrete's CTE depends on 2 aggregates and the cement paste, a model was presented based on the CTE of the cement paste and its packing density to estimate the CTE of the concrete.

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Influence of ground granulated blast furnace slag on cracking potential of high performance concrete at early age

Shen

Jiao

Gao

et al. 2020

Construction and Building Materials

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Effect of Fly Ash and Slag Powder on Coefficient of Thermal Expansion of Concrete

Cited by 4 publications

References 5 publications

Research on the Early-Age Cracking of Concrete Added with Magnesium Oxide under a Temperature Stress Test Machine

Research on the Early-Age Cracking of Concrete Added with Magnesium Oxide under a Temperature Stress Test Machine

Modeling Concrete Thermal Expansion Based on the Packing Density Theory

Influence of ground granulated blast furnace slag on cracking potential of high performance concrete at early age

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