Uniaxial tensile strength and tensile Young’s modulus of fly-ash concrete at early age

Yoshitake, Isamu; Zhang, Wenbo; Mimura, Yōichi; Saito, Tadashi

doi:10.1016/j.conbuildmat.2012.11.022

Cited by 23 publications

(7 citation statements)

References 3 publications

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“…It should be noted that the data shown in Figures 3(b-c) is acquired in compression -as such, while the elastic modulus of PCM-containing mixtures is noted to degrade with their increasing dosage, further work is needed to quantify changes in the tensile modulus of such systems, and any changes therein as a function of the stiffness of inclusions present due to complexities including interface debonding (N.B. : For typical cementitious formulations, the tensile and compressive elastic modulus are often within ± 30% of each other [53][54][55][56][57] Figure 4 shows the shrinkage response of the plain and inclusion-containing cementitious mixtures as a function of time for two drying regimes, i.e., partially sealed over the first 7 days, followed by: (i) drying at 50% RH (Figure 4a), and, (ii) 75% RH (Figure 4b) over the subsequent 3 days. Expectedly, both series of mixtures show a similar extent of free shrinkage and mass loss over the first 7 days.…”

Section: Results and Discussion 31 Strength Behavior: Contrasting Tmentioning

confidence: 99%

Restrained shrinkage cracking of cementitious composites containing soft PCM inclusions: A paste (matrix) controlled response

Wei¹,

Falzone²,

Das

et al. 2017

Materials & Design

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The addition of phase change materials (PCMs) has been proposed as a means to mitigate thermal cracking in cementitious materials. However, the addition of PCMs, i.e., soft inclusions, degrades the compressive strength of cementitious composites. From a strength-of-materials viewpoint, such reductions in strength are suspected to increase the tendency of cementitious materials containing PCMs to crack under load (e.g., volume instability-induced stresses resulting from thermal and/or hygral deformations). Based on detailed assessments of free and restrained shrinkage, elastic modulus, and tensile strength, this study shows that the addition of PCMs does not alter the cracking sensitivity of the material. In fact, the addition of PCMs (or other soft inclusions) enhances the cracking resistance as compared to a plain cement paste or composites containing equivalent dosages of (stiff) quartz inclusions. This is because composites containing soft inclusions demonstrate benefits resulting from crack blunting and deflection, and improved stress relaxation. As a result, although the tensile stress at failure remains similar, the time to failure (i.e., macroscopic cracking) is considerably extended in the case of PCM-containing composites. More generally, the outcomes indicate that dosages of soft(er) inclusions, and the resulting decrease in compressive strength does not amplify the cracking risk of cementitious composites.

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Section: Results and Discussion 31 Strength Behavior: Contrasting Tmentioning

confidence: 99%

Restrained shrinkage cracking of cementitious composites containing soft PCM inclusions: A paste (matrix) controlled response

Wei¹,

Falzone²,

Das

et al. 2017

Materials & Design

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“…Shafaatian et al studies the mechanism of fly ash action in reducing ASR effect. The experiments showed that fly ash reduces the amount of OHions in the solution, increases the strength of concrete specimens (Yositake et al, 2013), (Shafaatian et al, 2012) and reduces the dissolution of aggregates containing silica dioxide (Shafaatian et al, 2012).…”

Section: Experiments and Active Substancementioning

confidence: 99%

Research of Alkali Silica Reaction in Concrete With Active Mineral Additives

Grinys

Bocullo

Gumuliauskas

2014

Journal of Sustainable Architecture and Civil Engineering

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This paper analyses the effect of mineral additives on alkali-silica reaction. Amorphous SiO 2 contained in concrete aggregate is known for reactions with Na 2 O and K 2 O that cause concrete expansion and cracking. Concrete expansion is the result of silicates reaction (ASR). Alkali silica gel is a reaction product having expanding properties. Expanding silica gel creates stress that causes concrete cracking. The paper investigates the elimination of the negative effect of ASR by using fly ash as active mineral additive. In the tests active mineral additive (fly ash) is expected to reduce the effect of alkali-silica reaction and volumetric strain.

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“…The stress at the maximum strain in the uniaxial tensile test can be used to estimate the cracking stress of cement paste. 40 Therefore, in this section, uniaxial stress–strain tests were carried out on C0 and C007 cement paste samples cured at 50 and 500 °C, and the experimental results are shown in Figure 9 . Figure 9 a is the uniaxial stress–strain curve of the cement paste cured at 50 °C, and Figure 9 b is the uniaxial stress–strain curve of the cement paste cured at 500 °C.…”

Section: Resultsmentioning

confidence: 99%

“…According to the analysis of compressive strength and tensile strength of cement sample in sections and , it is found that when the graphite content is 0.07%, the cement paste has better mechanical properties at both low temperature and high temperature. The stress at the maximum strain in the uniaxial tensile test can be used to estimate the cracking stress of cement paste . Therefore, in this section, uniaxial stress–strain tests were carried out on C0 and C007 cement paste samples cured at 50 and 500 °C, and the experimental results are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Mechanical Properties of Graphite-Oil Well Cement Composites under High Temperature

2022

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Under the condition of heavy oil thermal recovery, the cement sheath is easy to crack in the high temperature environment, resulting in the decrease of cement paste strength, which may further cause sealing failure and oil and gas production safety accidents. In this paper, the influence of graphite on the mechanical properties of cement paste under the simulated thermal recovery of heavy oil was studied, and its mechanism is explored by testing and analyzing the microstructure. The phase composition and microstructure of graphite–cement composites were determined by X-ray diffraction analysis (XRD) and scanning electron microscope (SEM), and the thermogravimetric analyzer (TG/DTG) was used to analyze the heat resistance of the graphite–cement composites. The results show that the addition of graphite significantly improved the strength and deformation resistance of the Class G oil well cement at high temperature (300, 400, and 500 °C) and low temperature (50 °C), and the optimal addition amount is 0.07%. The microscopic analysis shows that the incorporation of graphite promoted the formation of hydration products, and played a role in filling pores and reducing microcracks in cement pastes. At the same time, due to the better thermal conductivity of graphite, it can balance the internal thermal stress of the cement pastes and inhibit the strength decline of cement pastes under high temperature environments. The integrity of cement pastes was guaranteed through the mechanism of “crack deflection” and “crack bridging”. The research results of this paper have presented a certain theoretical basis and new ideas for the development of cementing slurry systems in heavy oil thermal recovery wells.

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Uniaxial tensile strength and tensile Young’s modulus of fly-ash concrete at early age

Cited by 23 publications

References 3 publications

Restrained shrinkage cracking of cementitious composites containing soft PCM inclusions: A paste (matrix) controlled response

Restrained shrinkage cracking of cementitious composites containing soft PCM inclusions: A paste (matrix) controlled response

Research of Alkali Silica Reaction in Concrete With Active Mineral Additives

Mechanical Properties of Graphite-Oil Well Cement Composites under High Temperature

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