• Title/Summary/Keyword: SRA concrete

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Study on Prediction of Drying Shrinkage of Concrete using Shrinkage Reducing Agent (수축저감제를 사용한 콘크리트의 건조수축 예측에 관한 연구)

  • Seo, Tae-Seok;Choi, Hoon-Jae
    • Journal of the Korea Institute of Building Construction
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    • v.16 no.4
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    • pp.297-303
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    • 2016
  • Shrinkage Reducing Agent(SRA) was developed in order to control drying shrinkage cracks in concrete, and the use of SRA is increasing since it can control drying shrinkage cracks and improve the quality of concrete structures. Although there are many types of prediction equations of drying shrinkage strain, there is no prediction method which can consider the effect of SRA up to the present. Therefore, it is impossible to predict the tensile stress generated by drying shrinkage of SRA concrete, and to investigate the quantitative serviceability limit state of SRA concrete. In this study, the drying shrinkage of SRA concrete was investigated by experiment and analysis in order to suggest the predictability of drying shrinkage of SRA concrete. As a result, AIJ model, ACI model, GL2000 model showed there was a correlation between the predicted values and the experimental values within the error range of ${\pm}10%$. However, CEB-FIP model and B3 model underestimated the experimental values.

Super Retarding Agent Affecting Setting Time of Concrete Using Mineral Admixture (혼화재를 사용한 콘크리트의 응결 시간에 미치는 초지연제의 영향)

  • Jeon Chung Keun;Kim Jong;Han Min Cheol;Shin Dong An;Oh Sean Kyo;Han Chean Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.11a
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    • pp.643-646
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    • 2005
  • This paper reports the influence of super retarding agent(SRA) on the setting time of concrete incorporating mineral admixture including fly ash(FA), expansive additive(EA), silica fume(SF), blast furnace slag(BS) and blast furnace slag along with fly ash(BS+FA). An increase in SRA resulted in retarding the setting time of control concrete, while the use of mineral admixture led to a delay of setting time markedly, compared with that of control concrete under no SRA content. Meanwhile, An increase in SRA in concrete with mineral admixture exhibited comparable setting delay with control concrete. Furthermore, in case of the use of BS and SF, acceleration of setting time was observed with increase of SRA content. It is considered that proper dosage of SRA of concrete with SF and BS to secure similar setting delay with control concrete require rather larger than that of control concrete. Accordingly, For concrete with mineral admixture, in order to decide the proper dosage of SRA, application of correction factors is needed.

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Physical Properties and Drying Shrinkage of Concrete Using Shrinkage Reducing Admixtures (수축저감제를 사용한 콘크리트의 물성변화 및 건조수축 저감 특성)

  • Han, Cheon-Goo;Song, Seung-Heon
    • Journal of the Korea Institute of Building Construction
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    • v.5 no.3 s.17
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    • pp.101-107
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    • 2005
  • This paper reports the contribution of Shrinkage reducing admixture(SRA) to the physical properties and drying shrinkage of concrete. Dosage of SRA is varied with. For the properties of fresh concrete, an increase in SRA dosage results in a decrease in fluidity and air content, while setting time is accelerated. For the properties of hardened concrete, the incorporation of mineral admixture leads to a decrease in compressive strength at early age, whereas after 28 days, the incorporation of fly ash(FA) and blast furnace slag(BS) has greater compressive strength than conventional concrete without admixture. The use of SRA results in a decrease in compressive strength. The incorporation of SRA with every $1\%$ increase causes the decrease of compressive strength by as much as $3\~6\%$. For drying shrinkage properties, the incorporation of FA and BS reduces drying shrinkage slightly. The use of SRA also decreases drying shrinkage. Every $1\%$ of increase in SRA dosage can reduce drying shrinkage by as much as $10\~15\%$

Properties of Shrinkage in Concrete Incorporating Shrinkage Reducing Agent and Expansive Additive (수축저감제와 팽창재를 병용 치환한 콘크리트의 수축 특성)

  • 김광화;문학룡;심영태;이병상;정용희;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2004.05a
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    • pp.61-64
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    • 2004
  • This study is to investigate the engineering and shrinkage properties of concrete incorporating shrinkage reducing agent(SRA) and expansive additive(EA) in order to reduce shrinkage of concrete. According to results, as for the properties of fresh concrete, increase in, SRA and EA content leads to reduce the fluidity but to increase the air content, and as for setting time, there is little difference. For strength properties, it decreased with an increase in SRA dosage and increased up to 5% of EA content. For the properties of drying shrinkage, it shows decline tendency with an increase in SRA and EA content reiteratively. It alto reduces significantly with the combination of SRA-EA systems due to the combined effect of the admixture. In the scope of this paper, it is found that the use of SRA with 0.5% and EA with 5% has optimum effects on the various properties of concrete. And under the combination of SRA and EA, it can reduce drying shrinkage about 37%.

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Mock-up Test on the Reduction of Drying Shrinkage Crack in Structural Concrete (구조체 콘크리트의 건조수축 균열저감에 관한 Mock-up 실험)

  • Yoon Seob;Song Seung Heon;Han Min Cheol;Kim Kyeong Hwan;Jong Young Hee;Han Cheon Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.393-396
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    • 2005
  • This paper presents the results of drying shrinkage of concrete using shrinkage-reducingadmixture(DSRA) studied by the authors through mock-up test. DSRA is proportioned by expansive admixture and shrinkage reducing agent(SRA). Flowing concrete method is also applied to assist the concrete to reduce drying shrinkage by decreasing water content at the same time. The use of EA and SRA does not affect fluidity, bleeding and setting time. Compressive strength of concrete using EA along with SRA exhibited less than that of plain concrete. However, The compressive strength with combination of EA-SRA along with flowing concrete method shows comparable to that of plain concrete. The application of developed method can contribute to reducing drying shrinkage by as much as 30-40$\%$ compared with that of plain concrete.

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Drying Shrinkage of Concrete Combining Expansive Additives and Shrinkage Reducing Agent (팽창재와 수축저감제를 병용한 콘크리트의 건조수축 특성)

  • Han, Cheon-Goo;Han, Min-Cheol;Song, Seung-Heon;Yoon, Seob
    • Journal of the Korea Concrete Institute
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    • v.18 no.3 s.93
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    • pp.397-404
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    • 2006
  • This paper investigates experimentally the effect of combined addition of expansive additive and shrinkage reducing agent(SRA) on setting time, compressive strength and drying shrinkage of concrete. An increase of EA and SRA content leads to a reduction in flowability, which causes the increase of superplasticizer dosage, while air content increases. For setting time, in spite of increased superplasticizer dosage, with the increase of EA and SRA, setting time shortens. This is due to the presence of alkali ion by SRA and the faster formation of ettringite. At dosage of 5.0% of EA, concrete has the highest compressive strength and above that dosage, compressive strength decreased. On the contrary, the increase of SRA dosage results in a decrease in compressive strength. Combined addition of EA of 5.0% and SRA of 1.0% shows a comparable strength with control concrete. For drying shrinkage, as expected, the increase of EA and SRA dosage leads to reduction of drying shrinkage markedly. Moreover, combined addition of EA and SRA has better drying shrinkage reduction effect than individual use of EA and SRA by as much as $5{\sim}16%$. Optimal combination of EA and SRA is fixed at 5.0% of EA and 0.5% of SRA based on the consideration of the effect of EA and SRA on fresh state, compressive strength and shrinkage of concrete.

Physical Properties of Concrete Using Shrinkage Reducing Admixture and Expansive Additive (수축저감제와 팽창재를 혼입한 콘크리트의 물리적 특성)

  • Jung, Yang-Hee;Song, Young-Chan;Kim, Yong-Ro;Han, Hyung-Sub;Kim, Ook-Jong;Lee, Do-Bum
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.919-922
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    • 2008
  • This paper reports the physical and shrinkage properties of concrete using expansive additive(E) and three shrinkage reducing admixtures(SRA1, 2, 3) in order to reduce shrinkage of concrete. For the properties of fresh concrete, the use of SRA1, 2, 3 results in a increase in fluidity and decrease in the dosage of super plasticizer as much as 0.05$\sim$0.1%. And For the properties of hardened concrete, the use of SRA1, 2, 3 results in a decrease in compressive, tensile and flexural strength slightly. For drying shrinkage properties, the use of SRA3 is the most effective for reduction of shrinkage, and the next best way to reduce shrinkage is combination with expansive additive(E) and shrinkage reducing admixture(SRA) or the using of expansive additive(E).

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Execution of Mass Concrete for Mat Foundation Using Setting Time Difference with Super Retarding Agent for Reducing Hydration Heat (초지연제의 응결시간차 공법을 이용한 기초 매트 콘크리트의 수화열 저감 시공)

  • Jeon Chung Keun;Yoon Chi Whan;Song Seung Heon;Shin Dong An;Oh Seon Gyo;Han Cheon Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.144-147
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    • 2004
  • In this paper, field application of mass concreting using super retarding agent(SRA) are discussed based on setting. time difference with SRA in big discount market in Chongju. Mechanical and physical properties of .concrete are investigated. Temperature history of concrete is also measured. Slump and air content meet the requirement of target value. Compressive strength of concrete exceeded the nominal strength with 24MPa. Compressive strength of SRA concrete is higher than that of plain concrete by about $3\~4\%$. For temperature history, peak temperature of concrete at middle section at top concrete layer reached $49.6^{\circ}C$ within 24hours, and at bottom concrete layer, $54.6^{\circ}C$ within 42hours. Based on the naked eye's observation, no crack was found at mass concrete.

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Study for Curling Control of Plain Concrete in Underground Parking Lot (지하주차장 무근콘크리트 컬링제어를 위한 연구)

  • Seo, Tae-Seok;Choi, Hoon-Jae
    • Journal of the Korea Institute of Building Construction
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    • v.18 no.3
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    • pp.243-249
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    • 2018
  • The study for curling control of plain concrete in underground parking lot was conducted in this study. The shrinkage reducing agent(SRA) was used to minimize the curling deformation of plain concrete in underground parking lot. For the quantitative curling control, the simplified prediction method applying the deflection theory of cantilever beam was proposed too, and the validity of prediction method was examined through the comparison between the experimental values and predictive values. In result, the curling of SRA 1.0% concrete was about 30% less than that of SRA 0.0% concrete, and the possibility of curling estimation by the simplified prediction method was confirmed through the comparison between the experimental values and predictive values.

Effect of Expanding Admixture and Shrinkage Reducing Agent on the Shrinkage Reducing Properties of Ultra High Performance Cement Mortar (팽창재 및 수축저감제가 초고성능 시멘트 모르타르의 수축특성에 미치는 영향)

  • Han, Dong-Yeop;Yu, Myoung-Youl;Lee, Hyun-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.61-64
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    • 2006
  • Comparing with traditional high performance concrete, ultra high performance concrete (UHPC) has the property of high-tenacity. However, drying shrinkage and autogenous shrinkage can be arisen as the major defect to UHPC. In this study, therefore, it was tested to reduce drying shrinkage and autogeneous shrinkage by adding expanding admixture (EA) and shrinkage reducing agent (SRA). As a result, for a case drying shrinkage, the shrinkage was decreased by 94% when EA was exchanged, and it was decreased by 64% when SRA was added. For the case of autogenous shrinkage, the mortar was expanded at early age and the shrinkage was decreased by 87% when EA was exchanged, and the shrinkage was decreased by 70% when SRA was added.

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