• Title/Summary/Keyword: 수화수축

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Effects of Specimen Shape on Hydration Heat and Autogenous shrinkage at an early (시험체 형상에 따른 고강도 콘크리트의 수화열 및 자기수축 초기특성 분석)

  • Lee, Eui-Bae;Koo, Kyung-Mo;Kim, Young-Sun;Kim, Young-Duck;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.915-918
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    • 2008
  • Hydration heat and autogenous shrinkage are generated essentially by the same hydration. Many researchers have studied the close relationship between hydration temperature and autogenous shrinkage but hardly any research has been undertaken to explain the specific numerical relation. In this study, early age properties of hydration heat and autogenous shrinkage of specimen whose section size was changed were analyzed, and relationship between hydration heat and autogenous shrinkage was investigated. In the results of the study, inner temperature and autogenous shrinkage increased as the section size increased. And rise and rise ratio of hydration temperature and autogenous shrinkage in hydration heating section and autogenous shrinking section are increased too. Temperature rise and autogenous shrinkage rise increased respectively, as hydration heating velocity and autogenous shrinking velocity increased. And autogenous shrinkage rise and autogenous shrinking velocity increased as hydration heating velocity increased.

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The Analysis of Early Age Properties of Hydration Heat and Autogenous Shrinkage according to Specimen Size and Retardation of Hydration (시험체 크기 및 수화지연 효과에 따른 초기재령 수화발열 및 자기수축 특성 분석)

  • Kim, Gyu-Yong;Koo, Kyung-Mo;Lee, Hyoung-Jun;Lee, Eui-Bae
    • Journal of the Korea Concrete Institute
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    • v.21 no.4
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    • pp.481-488
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    • 2009
  • It has been reported that the magnitude and the development rate of autogenous shrinkage of cement paste, mortar and concrete were affected by history and magnitude of inner temperature at an early age. But it was not enough to explain the relation between hydration heat and autogenous shrinkage at an early age, because there was no certain analysis on histories of hydration heat and autogenous shrinkage in previous studies. In our prior study, to understand the relationship between hydration heat and autogenous shrinkage of concrete at an early age, the analysis method for histories of hydration heat and autogenous shrinkage was suggested. Based on this method, early age properties of hydration heat and autogenous shrinkage of high strength concrete with different sizes and hydration retardation were investigated in this study. As a result of the study, properties of hydration temperature and autogenous shrinkage were different according to specimen size and hydration retardation. However, there was a close relationship between hydration temperature and autogenous shrinkage at an early age, especially between HHV and ASV as linear slopes of the sections where hydration temperature and autogenous shrinkage increase rapidly; the higher HHV, the higher ASV and the greater ultimate autogenous shrinkage. And it was found that, among the setting time, bend point and temperature increasing point, they were close relationship each other on cement hydration process.

A Fundamental Study on the Correlationship between Hydration Heat and Autogenous Shrinkage of High Strength Concrete at an Early Age (초기재령 고강도콘크트의 수화발열과 자기수축 특성의 상관관계에 관한 기초적 연구)

  • Kim, Gyu-Yong;Lee, Eui-Bae;Koo, Kyung-Mo;Choi, Hyeong-Gil
    • Journal of the Korea Concrete Institute
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    • v.20 no.5
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    • pp.593-600
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    • 2008
  • In this study, to analyze the correlation between hydration heat and autogenous shrinkage of high strength concrete at an early age, hydration heating velocity and autogenous shrinking velocity as quantitative coefficients which represent the main properties of hydration heat and autogenous shrinkage were proposed. Two coefficients were calculated by statistical analysis and were equal with the regression coefficient. The complemented semi-adiabatic temperature rise test as test method to evaluate the hydration heat and autogenous shrinkage of concrete were proposed. In results of proposed test and analysis method, it was possible that early age properties of hydration heat and autogenous shrinkage of concrete were expressed numerically, and autogenous shrinkage was represented by equation with coefficients of hydration heat.

The statistical method for quantitative analysis of hydration heat and autogenous shrinkage of concrete (콘크리트 수화발열 및 자기수축 특성의 정량적 분석을 위한 통계적 방법)

  • Lee, Eui-Bae;Lee, Hyung-Jun;Koo, Kyung-Mo;Na, Chul-Sung;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.645-648
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    • 2008
  • In this study, to evaluate the correlation between hydration heat and autogenous shrinkage of high strength concrete in early age, statistical method present numerically hydration heat and autogenous shrinkage was studied. First of all, hydration heating velocity and autogenous shrinking velocity as quantitative coefficients which represent the main properties of hydration heat and autogenous shrinkage were proposed. Two coefficients were calculated by statistical analysis and were equal with the regression coefficient. To verify the validity of the proposed statistical analysis method, data of hydration heat and autogenous shrinkage gathered by a real experiment were analyzed by it. In results, properties of hydration heat and autogenous shrinkage of high strength concrete in early age were analyzed quantitatively. Also evaluation and comparison of the correlation between hydration heat and autogenous shrinkage with numerical value were possible.

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A Statistical Analysis on Hydration Heat and Autogenous Shrinkage of High Strength Concrete in Early Age Using Blast Furnace Slag (고로슬래그 미분말을 다량 사용한 고강도 콘크리트의 초기 수화발열 및 자기수축 특성에 관한 통계적 분석)

  • Koo, Kyung-Mo;Nam, Jeong-Soo;Lee, Eui-Bae;Kim, Young-Duck;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.657-660
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    • 2008
  • In this study, quantitative analysis on effect of hydration heat and autogenous shrinkage of concrete using BFS was studied. Especially, it analyze section data statistically which hydration heat and autogenous shrinkage rise, and it appeared the correlation of hydration heat and autogenous shrinkage as well as quantitative coefficients of the main properties. As a result, the section which hydration heat and autogenous shrinkage of BFS-50 rise rapidly is delayed than OPC, but the slope of hydration heat and autogenous shrinkage in that section appeared similar shape in each mixing. Finally it will be possible to control the amount of autogenous shrinkage because hydration heating velocity and autogenous shrinking velocity are decreased by using BFS.

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Properties of Hydration Heat and Autogenous Shrinkage of High-Strength Mass Concrete with Latent Heat Material (잠열재를 사용한 고강도 매스 콘크리트의 수화열 및 자기수축 특성)

  • Lee, Eui-Bae;Koo, Kyung-Mo;Nam, Jeong-Soo;Kim, Young-Sun;Kim, Young-Duck;Kim, Gyu-Yong
    • Proceedings of the Korea Concrete Institute Conference
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    • 2009.05a
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    • pp.315-316
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    • 2009
  • In this study, latent heat material was used to reduce hydration heating velocity of high-strength mass concrete. And the properties of hydration heat and autogenous shrinkage, and the relationship between hydration heat and autogenous shrinkage of high-strength mass concrete were numerically investigated.

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A Study on the Hydration Reaction Model of Expansive Additive of Ettringite-Gypsum Type (에트링가이트-석탄 복합계 팽장재의 수화반응 모델에 관한 연구)

  • Park Sun Gyu;Takahumi Noguchi;Kim Moo-Han
    • Journal of the Korea Concrete Institute
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    • v.17 no.4 s.88
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    • pp.581-586
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    • 2005
  • High-performance concrete (HPC), which is particularly sensitive to self-desiccation, is required to be durable even in severe environmental conditions, i.e. costal area, cold district, etc. However, in recent years, some attention was particularly given to cracking sensitivity of high performance concrete at early age. It has been argued and demonstrated experimentally that such concrete undergoes autogenous shrinkage due to self-desiccation at early age under restrained condition, nd, as a result, internal tensile stress may develop, leading to micro cracking and macro cracking. This shrinkage-introduced crack produces a major serviceability problem for concrete structures. One possible method to reduce cracking due to autogenous shrinkage is the addition of expansive additive. Tests conducted by many researches have shown the beneficial effects of addition of expansive additive for reducing the risk of autogenous shrinkage-introduced cracking. However, the research on hydration model of expansion additive has been hardly researched up to now. This paper presents a study of the hydration model of Ettringite-Gypsum type expansive additive. As a result of comparing forecast values with experiment value, proposed model is shown to expressible of hydration of expansive additive.

Prediction of Autogenous Shrinkage on Concrete by Unsaturated Pore Compensation Hydration Model (불포화 공극 보정 수화도 모델을 이용한 콘크리트의 자기수축 예측)

  • Lee, Chang Soo;Park, Jong Hyok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5A
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    • pp.909-915
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    • 2006
  • To predict autogenous shrinkage of concrete, unsaturated pore compensation factor could be calculated by experiments of autogenous shrinkage of cement paste on the assumption that the differences between degree of hydration and strain rate of autogenous shrinkage are unsaturated pore formation rate. Applying unsaturated pore compensation factor on modified Pickket model considering contribution factor and non-contribution factor to autogenous shrinkage of concrete, experimental data and existing model were compared. From the results modified Pickket model was verified to present similar tendency between Tazawa model and experimental data, but CEB-FIP model might be corrected because this model uses ultimate autogenous shrinkage underestimated and the same autogenous time function of concrete material properties considering only compressive strength.

Properties of Autogenous Shrinkage according to Hydration Heat Velocity of High Strength Concrete Considering Mass Member (매스부재를 고려한 고강도콘크리트의 수화발열상승속도 조절에 따른 자기수축 특성)

  • Koo, Kyung-Mo;Kim, Gyu-Yong;Hong, Sung-Hyun;Nam, Jeong-Soo;Shin, Kyoung-Su;Khil, Bae-Su
    • Journal of the Korea Institute of Building Construction
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    • v.12 no.4
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    • pp.369-376
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    • 2012
  • In this study, to reduce the hydration heat velocity (HHV) of high-strength mass concrete at early ages, phase change materials (PCM) that could absorb hydration heat were applied, and the changes in autogenous shrinkage were investigated, as well as the relationship between the hydration temperature and autogenous shrinkage. The acceleration of the cement hydration process by the PCM leads to an early setting and a higher development of the compressive strength and elastic modulus of concrete at very early ages. The function of PCM could be worked below the original melting point due to the eutectic effect, while the hydration temperature and HHV of high-strength mass concrete can be decreased through the use of the PCM. A close relationship was found between the hydration temperature and autogenous shrinkage: the higher the HHV, the greater the ultimate autogenous shrinkage.

A Study On the Chemical shrinkage and Autogenous Shrinkage of High strength Concrete (고강도 콘크리트의 수화수축과 자기수축의 실험연구)

  • Heo, Woo-Young;Kim, Wha-Jung
    • Journal of the Korea Institute of Building Construction
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    • v.4 no.2
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    • pp.81-88
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    • 2004
  • The purpose of this study is to investigate the chemical shrinkage and autogenous shrinkage of high strength cement paste and silica fume and fly ash and sand to cement ratio by the method of volumetric tests, and also investigate the autogenous shrinkage of high measurement method, and compare the results of volumetric test and linear length measurement test. A series of cement paste which have W/C ratio of 25%, 35%, 45% respectively were planed to study the effect of the W/C ratio to the shrinkages, and a series of cement paste which were replaced the cement by the silica fume and fly ash with 5%, 10%, 15% as the mass of cement respectively were planed to investigate the effects of poazolana to the shrinkages. A series of mortar which have a C/S ratio of 1:1, 1:1.5, 1:2 respectively were planed to investigate the shrinkage resistant effect of aggregate.