In situ measurement of coefficient of thermal expansion in hardening concrete and its effect on thermal stress development

Yeon, Jung Heum; Choi, Seongcheol; Won, Moon

doi:10.1016/j.conbuildmat.2012.07.111

Cited by 44 publications

(21 citation statements)

References 22 publications

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“…Results from several studies [18][19][20][21][22][23][24][25][26] show that the CTE is strongly dependent on the concrete age. It rapidly decreases from a rather high value for fresh concrete to values of 10-30 × 10 −6 /K at the time near to final setting, as summarized by Zhutovsky and Kovler.…”

Section: The Evolution Of Cte Of Hardening Concrete-an Overview Of mentioning

confidence: 99%

“…• The "saw-tooth temperature" method, in which the sample is subjected to heating-(holding)-cooling cycles. [18][19][20][21][22][23] The CTE is calculated from the volumetric 18 or length change. [19][20][21][22][23] One heating-(holding)-cooling cycle takes 60 min 18 up to 8 hr 23 depending on the sample dimensions.…”

Section: The Evolution Of Cte Of Hardening Concrete-an Overview Of mentioning

confidence: 99%

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Investigations on the coefficient of thermal expansion of a low‐calcium fly ash‐based geopolymer concrete

Dehn

2017

Structural Concrete

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In this paper, the deformation of a sealed low‐calcium fly ash‐based geopolymer concrete during heat curing was investigated. The sealed sample underwent thermal deformation due to temperature change and possible autogenous deformation related to alkaline activation of the fly ash. For the separation of the both deformation types the coefficient of thermal expansion (CTE) is a paramount issue. The CTE evolution of the geopolymer concrete from plastic to hardened state was determined by means of a new method proposed in this paper. Based on the experimental results, the CTE is mathematically described as a function of the so‐called equivalent time. The thermal dilation during heat curing was then calculated using the CTE equation. The autogenous shrinkage of the fly ash‐based geopolymer concrete is comparatively low. The thermal dilation during the heat curing cannot completely reverse, if the concrete is cooled down to its temperature at the beginning of the heating. After the heat curing no further autogenous deformation was observed on sealed samples continuously cured at room temperature.

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Section: The Evolution Of Cte Of Hardening Concrete-an Overview Of mentioning

confidence: 99%

Section: The Evolution Of Cte Of Hardening Concrete-an Overview Of mentioning

confidence: 99%

Investigations on the coefficient of thermal expansion of a low‐calcium fly ash‐based geopolymer concrete

Dehn

2017

Structural Concrete

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“…If tri-or βdicalcium silicate is placed in a magnesium sulphate solution, formation of gypsum crystals occurs rapidly. The hydrated calcium silicates react in the following general manner: The reason why this reaction proceeds completely, while with sodium sulphate does not occur, is to be found in the low solubility of magnesium hydroxide and resulting low pH value of its saturated solution (Greene, 1962;Mohammed et al, 2014b;Radwan et al, 2012a;Yeon et al, 2013;Radwan et al, 2012b;Fiertak and Stryszewska, 2013). The hydrated magnesium silicate appears to have no binding power, in contrast to calcium silicate hydrate and its formation represents therefore a final stage in the deterioration of concrete attacked by magnesium sulphate solution.…”

Section: Aggressive Attack On Cement Pastesmentioning

confidence: 99%

Effect of Sulfonated Acetone Formaldehyde (SAF) on the Firing Resistance and Aggressive Attach of SRC-SF Composite Cement Pastes

Osman¹,

Al-Masry²

2015

American Journal of Engineering and Applied Sciences

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This work aimed to study the effect of the dosage of laboratory synthesized Sulfonated Acetone Formaldehyde (SAF) on the physicmechanical characteristics and durability of SF-SRC cement pastes immersed in 4% MgCl 2 or 4% MgSO 4 solutions or at elevated temperatures up to 800°C. The compressive strength of thermally treatment cement pastes with 1.5% SAF increases up to 600°C, then decreases up to 800°C. Presence of 2.0% SAF works to produce a compact cementing structure, which decreases the accessibility of the penetration of chloride as well as sulphate ion penetration and enhances the durability, hence the total chloride and sulphate contents diminished.

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“…l em (17) where: ρ -degree of reinforcement, l Em -length of relaxation zone, v o -half crack width in concrete element, m De -parameter describing stable state of cracking. Based on expressions (16), (17) a general formula for the calculation of the distance between reinforcing bars was provided, assuming bar diameter ϕ, maximum crack width and parameter m De…”

Section: Cracks Controlmentioning

confidence: 99%

The Influence of Ambient Temperature on RC Tank Walls Watertightness in Research and Theory

Zych

2015

Period. Polytech. Civil Eng.

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IntroductionThe direct cause of semi-massive RC tank walls cracking is the decrease in wall temperature after a rapid hydration process [1]. Early-age cracking could be avoided by application of air cooled pipes [2]. The degree of temperature decrease in walls depends, among other things, on weather conditions which accompany the construction process. Moreover, ambient conditions are the most difficult factors to predict for a designer and a contractor. Eurocode Standard [3] guidelines define the way of providing reinforcement taking into account imposed strain in two element types, i.e. those restrained on two opposite ends or those restrained only by their foundation. With regard to the latter option, "it has not been studied so systematically and there appears to be little published guidance". One of the first studies on walls restrained along the bottom edge was conducted by Stoffers [4]. During his experiments deformations were not induced by temperature change but by controlled uploading of a post-tensioned beam. Owing to a large number of tested elements with various percentage and various distribution of reinforcement, crack morphology was presented depending on reinforcement percentage and the curvature of a given element. However, the elements had small dimensions and were made of micro-concrete, i.e. concrete with scaled-down granulometric composition. This concrete had an average compressive strength of about 30 MPa. Other researchers Rostásy and Henning [5], Ivanyi [6] Paas [7] formulated models to calculate the crack width in the walls restrained along their bottom edge (based at least partially on experimental investigations [4] adopting in their models the possibility of crack occurrence spaced at (1÷1.5) H. These models show the percentage of reinforcement needed to satisfy the condition of watertightness, i.e. limitation of through cracks to the value of w lim . ACI 207. 2R-95 [8] and , present the mechanism of crack development which depends on the wall height to length ratio. It should be emphasised that this approach focus on the mechanism of cracking, but not on the problem of watertightness as these structures have a low percentage of reinforcement. Zych [10] analyses various engineering models in terms of crack formation caused by imposed deformation in RC walls, comparing

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In situ measurement of coefficient of thermal expansion in hardening concrete and its effect on thermal stress development

Cited by 44 publications

References 22 publications

Investigations on the coefficient of thermal expansion of a low‐calcium fly ash‐based geopolymer concrete

Investigations on the coefficient of thermal expansion of a low‐calcium fly ash‐based geopolymer concrete

Effect of Sulfonated Acetone Formaldehyde (SAF) on the Firing Resistance and Aggressive Attach of SRC-SF Composite Cement Pastes

The Influence of Ambient Temperature on RC Tank Walls Watertightness in Research and Theory

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