The microstructure of concrete cured at elevated temperatures

Patel, Harshkumar; Bland, C. H.; Poole, A. B.

doi:10.1016/0008-8846(95)00036-c

Cited by 70 publications

(32 citation statements)

References 7 publications

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“…The accelerated curing conditions include using elevated temperatures [36] and accelerated carbonation [37]. It must be stated that predicting the behavior of stabilized materials, such as the rate of release of contaminants, is not easy.…”

Section: Discussionmentioning

confidence: 99%

Stabilization treatment of contaminated soil: a field-scale application in Shanghai, China

Zhang

Luo

Geng

et al. 2010

Front. Environ. Sci. Eng. China

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Stabilization is one of the best demonstrated available technologies for treating toxic pollutants in soils and has been used worldwide but is rarely used for treatment of contaminated sites in China despite many bench-scale studies. Here, a field-scale application of stabilization treatment in Shanghai, China was summarized to demonstrate the whole engineering process and the key technical issues regarding stabilization of contaminated soil. A site contaminated with arsenic (As) and polycyclic aromatic hydrocarbons (PAHs), formerly used as a lighting plant in Shanghai, was chosen as the demonstration site. Stabilizing measures were taken to treat the contaminated soil to reuse the site for residential purposes. The whole engineering remediation process consisted of phase I environmental site assessment (ESA) and phase II ESA, quantitative human health risk assessment, remediation alternatives evaluation, benchscale testing, remedial design, engineering implementation, and post-remediation assessment. A third party conducted evaluation monitoring indicated desirable results were achieved via the stabilization treatment. In addition, some technical obstacles related to soil stabilization treatment were discussed, including soil quality evaluation, stabilization effectiveness validation, and soil reuse assessment.

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Section: Discussionmentioning

confidence: 99%

Stabilization treatment of contaminated soil: a field-scale application in Shanghai, China

Zhang

Luo

Geng

et al. 2010

Front. Environ. Sci. Eng. China

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“…It was because recycled aggregate was more porous and weaker compared with natural aggregates as indicated by the results of the MIP and the 10% fines value. The detrimental effects of steam curing on the compressive strength of concrete were attributed to 30,31,22 : (a) accelerated temperature resulted in a coarse pore structure,(b) hydration products did not have enough time to diffuse evenly before hardening, and (c) the differences in the thermal expansion coefficients of different concrete constituents (i.e. especially air) led to formation of microcracks.…”

Section: Compressive Strengthmentioning

confidence: 98%

Influence of steam curing on hardened properties of recycled aggregate concrete

Poon

Kou

Chan

2006

Magazine of Concrete Research

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The effects of steam curing on the hardened properties of recycled aggregate concrete were investigated. In this study, two series of concrete mixtures with water/cement ratios of 0 . 55 and 0 . 45 were prepared. Recycled aggregates were used as 0, 20, 50 and 100% by volume replacements of natural coarse aggregate in the concrete mixtures. The concrete specimens underwent standard water-curing and steam-curing regimes. The test results showed that the strength of concrete decreased as the recycled aggregate content increased. An initial steam-curing regime increased the one-day strength of the concrete, but the corresponding 28-and 90-day strengths decreased. Furthermore, steam curing reduced the static modulus of elasticity of concrete compared with that of the water cured concrete. However, the negative effect of steam curing diminished as the recycled aggregate content increased. Moreover, steam curing decreased the drying shrinkage and increased the resistance against chloride ion penetration of the recycled aggregate concrete. The results demonstrate that one of the practical ways to utilise a higher percentage of recycled aggregates in concrete is 'precasting' with an initial steam curing stage immediately after casting. IntroductionRecycled aggregate (RA) has been used as a replacement of the natural aggregate for a number of years. The potential benefits and drawbacks of recycled aggregate concrete, when compared with equivalent concrete using natural aggregate, have been quite extensively studied. 1-11 The use of recycled aggregate generally increases the drying shrinkage, creep, carbonation rate and water sorptivity and decreases the compressive strength, modulus of elasticity and resistance to freezing and thawing of concrete compared with those of natural aggregate concrete. Hasaba et al. 12 reported that the drying shrinkage of concrete prepared with coarse recycled aggregate and natural sand was 50% higher than that of conventional concrete. When both coarse and fine recycled aggregates were used, the drying shrinkage of recycled aggregate concrete was as much as 70% higher than that of conventional concrete. Hansen and Boegh 13 reported that recycled aggregate concrete had 15 to 30% lower modulus of elasticity and 40 to 60% higher shrinkage than those of conventional concrete. Olorunsogo and Padayachee 14 found that the water sorptivity of concrete prepared with 100% recycled aggregate (by weight replacement) was approximately 39% greater than that of natural aggregate concrete at the curing age of 28 days. Dhir et al. 15 showed that the reduction in compressive strength of water-cured RC 30 (characteristic strength of 30 MPa) concrete measured at one year was less than 6 MPa regardless of the coarse recycled aggregate content.The negative effects of recycled aggregate on concrete quality limit the use of this material in structural concrete. However, the disadvantages of using recycled aggregate can be minimised in the precast concrete industry since it is easier to ensure the quality of such ...

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“…Glass fibers are the most susceptible to degradation without the absence of moisture and alkalinity [13]. The reaction of GFRP composite with the alkali in concrete is a major durability concern.…”

Section: Glass Transition Temperaturementioning

confidence: 99%

“…Many researchers revealed that the alkaline concrete will increase the additional stress, surface crack, and porosity under the steam-curing of high temperature and humidity [11][12][13][14][15]. Therefore, the influence of the curing system on GFRP bars embedded in concrete cannot be neglected.…”

Section: Introductionmentioning

confidence: 99%

Combined Effects of Curing Temperatures and Alkaline Concrete on Tensile Properties of GFRP Bars

Yang

Zhang

et al. 2017

International Journal of Polymer Science

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A significant number of studies have been conducted on the tensile properties of GFRP bars embedded in concrete under different environments. However, most of these studies have been experimentally based on the environmental immersion test after standard-curing and the lack of influence on the tensile properties of GFRP bars embedded in concrete during the curing process of concrete. This paper presents the results of the microscopic structures through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and tensile properties of GFRP bars, which were employed to investigate the combined effects of curing temperatures and alkaline concrete on tensile properties of GFRP bars. The results showed that the higher curing temperature aggravated the influence of the alkaline concrete environment on GFRP bars but did not change the mechanisms of mechanical degradation of the GFRP bars. The influence of different curing temperatures on the tensile strength of GFRP bars was different between the bare bar and bars in concrete. Finally, the exponential correlation equation of two different test methods was established, and the attenuation ratio of the tensile strength of GFRP bars embedded in concrete under different curing temperatures was predicted by the bare test.

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The microstructure of concrete cured at elevated temperatures

Cited by 70 publications

References 7 publications

Stabilization treatment of contaminated soil: a field-scale application in Shanghai, China

Stabilization treatment of contaminated soil: a field-scale application in Shanghai, China

Influence of steam curing on hardened properties of recycled aggregate concrete

Combined Effects of Curing Temperatures and Alkaline Concrete on Tensile Properties of GFRP Bars

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