• Title, Summary, Keyword: Super Retarding Agent

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A Method on the Control of Hydration Heat of Mass Concrete Considering the Difference of Setting Time (응결시간차를 활용한 매스콘크리트의 수화열 조정공법)

  • 심보길;윤치환;한민철;김기철;오선교;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.379-384
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    • 2001
  • This Paper Presents field application test results of mass concrete using super retarding agent. The field test was carried out at mat foundation(thickness 1m) of newly constructed information center of Chongju university. Placing lift composed of 2 layers, and each layer is 50cm. Fly ash and flowing method is also applied. Difference of setting time of concrete between with super retarding agent and without super retarding agent is considered. Concrete without super retarding agent is placed at upper layer and with super retarding agent at lower layer According to test results, the reducing method of hydration heat considering difference of setting time with super retarding agent can reduce the highest temperature about 3~4$^{\circ}C$, and delay the peak time about 3~4days. Compressive strength using super retarding agent is somewhat higher than that of normal concrete. Accordingly, super retarding agent does not affect the strength development.

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Setting and Mechanical Properties of Concrete Under Various Types and Contents of Super retarders (초지연제의 종류 및 혼입율 변화에 따른 콘크리트의 응결 및 역학적 특성)

  • 심보길;윤치환;전충근;한민철;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.1195-1198
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    • 2000
  • In this paper, setting and strength properties of concrete with contents of super retarding agent are discussed. Gluconic acid and sucrose and used for super retarding agent. According to experimental results, as super retarding agent content increases, slump show to be increased, while air content decrease about 1~2%. In case of setting properties, as super retarding agent content increases, setting time delays considerable. When gluconic acid and sucrose is added about 0.3%, it delays more than 10days. Compressive strength of concrete of concrete with super retarding agent shows to be higher than that without it. Retarding of setting time of concrete using gluconic acid is longer than that using sucrose.

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Estimation of the Strength Development of the Super Retarding Concrete Incorporating Fly Ash and Blast Furnace Slag (플라이애시와 고로슬래그를 조합 사용한 초지연 콘크리트의 강도증진)

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.5
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    • pp.119-125
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    • 2008
  • In this paper, the estimation of super retarding concrete incorporating mineral admixtures at the same time including fly ash(FA), blast furnace slag(BS) are studied based on maturity method. The setting time was retarded, as super retarding agent contents increase and curing temperature decreases. In addition, apparent activation energy by Arrhenius function was ranged from $24\sim35$ KJ/mol with slightly difference along with mixture proportion. This value is smaller than existing value $30\sim50$ KJ/mol. Based on strength development estimation. it exhibited comparable relativity between prediction value and measurement value. Therefore, this study provided effective strength development prediction value with super retarding agent contents and mineral admixture combination. Strength development prediction equation provided herein is possibly valid for estimating accurate strength development of the super retarding concrete at the job site.

Estimation of the Setting Time of the Super Retarding Concrete Combining Mineral Admixtures (혼화재를 조합 사용한 초지연 콘크리트의 응결시간 추정)

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.3
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    • pp.111-117
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    • 2008
  • This study provides the setting time prediction method of super retarding concrete incorporating mineral admixtures at the same time including fly ash(FA), blast furnace slag(BS) based on maturity method. The setting time was retarded, as super retarding agent contents increase and curing temperature decreases. In addition, apparent activation energy by Arrhenius function was ranged from $24{\sim}35KJ/mol$ with slightly difference along with mixture proportion. This value is smaller than existing value $30{\sim}50KJ/mol$. It is Indicated that equivalent age using setting time can be a proper method to predict setting time and it also exhibited comparable relativity between prediction value and measurement value. Therefore, this study provided setting time prediction value with super retarding agent contents and mineral admixture combination. Setting time prediction equation provided herein is possibly valid for estimating precise setting time of the super retarding concrete at the job site.

Construction Considering the Difference of Setting Time of Super Retarding Agent for Reduction of Hydration Heat of Footing Mass Concrete (기초 매스콘크리트의 수화열 저감을 위한 초지연제 응결시간차 공법의 현장 적용)

  • 황인성;배정렬;윤석명;김기철;오선교;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.95-98
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    • 2003
  • This paper presents the results of field experiment to apply the difference of setting tine method using super retarding agent for reducing hydration heat of mass concrete of foundation. According to the results, as the properties of fresh concrete, base concrete satisfies aimed slump and air content, and there is no difference of slump and air content with mixture of super retarding agent. The mixing ratio of super retarding agent is determined for setting time to be retarded by 12 hours in comparison with base concrete, but because the temperature of the air and concrete is low, the difference of setting time is retarded to 24 hours. In man concrete of foundation to which the difference of setting time method is applied, crack by hydration heat is not seen because the lower concrete of super retarding agent generates heat after generation of hydration heat of the upper concrete.

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Setting md Mechanical Properties of Concrete Using Saccharic Type Super Retarding Agent (당분류의 초지연제를 이용한 콘크리트의 응결 및 역학적 특성)

  • 한천구;한민철;윤치환;심보길
    • Journal of the Korea Concrete Institute
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    • v.14 no.4
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    • pp.589-596
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    • 2002
  • In this paper, setting and strength performances of concrete containing saccharic type super retarding agents are investigated under various kinds and contents of super retarding agents. According to test results, as super retarding agents contents increase, slump shows to be increased, while air contents decrease about 1∼2%. Setting time shows to be retarded considerably with increase of super retarding agents. It takes 20 days after mixing to reach final setting in case of concrete containing gluconic acid more than 0.3%. And 10 days after mixing in case of enhancing sucrose, white and brown sugar. Compressive strength of concrete containing super retarding agents is lower than that of plain concrete at early age. However, it keeps up with and exceeds the compressive strength of plain concrete at later age. White sugar md brown sugar shows positive performances in delaying setting time and strength compared to existing super retarding agents. n further investigations on durability are conducted, it is thought that application of white sugar as super retarding agent is available.

A Fundamental Study on the Control of Hydration Heat of Mass Concrete Using Setting Time Difference (응결시간차를 활용한 매스콘크리트의 수화열 조정에 관한 기초적 연구)

  • 배정렬;윤치환;김기철;한민철;오선교;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.41-45
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    • 2002
  • Placing lift is applied to place mass concrete in order to reduce thermal cracks by hydration heat. But they results in cold joint between placing lifts, which bring about the loss of strength, water tightness and undesirable appearance. Therefore, in this paper, mechanical and hydration heat of mass concrete using super retarding agent developed through previous study are investigated in order to reduce the hydration heat and place it without place lift. According to test results, placing lifts combined with normal concrete and concrete containing super retarding agent have positive effects on reducing hydration heat. Especially, the crack index by thermal stress of the concrete containing super retarding agent less than a quarter, compared to that of plain concrete without placing lifts, and less than a half, compared to that of plain concrete with placing lifts.

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A Study on the Control of Hydration Heat of Mass Concrete Using Super Retarding Agent (초지연제를 이용한 매스콘크리트의 수화열 조정에 관한 연구)

  • 유동수;심보길;윤치환;한민철;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.515-520
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    • 2001
  • Mass concrete is placed considering placing lifts in order to reduce thermal cracks by hydration heat. But they results in cold joint between placing lifts, which bring about the loss of strength, water tightness and undesirable appearance. Therefore, in this paper, mechanical and hydration heat of mass concrete using super retarding agent developed through previous study are investigated in order to reduce the hydration heat and place it without place lift. According to test results, placing lifts combined with normal concrete and concrete containing super retarding agent have positive effects on reducing hydration heat. Especially, the crack index by thermal stress of the concrete containing super retarding agent less than a quarter, compared to that of plain concrete without placing lifts, and less than a half, compared to that of plain concrete with placing lifts.

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A Study on the Control of Hydration Heat of Mass Control Using Super Retarding Agent (초지연제를 이용한 매스콘크리트의 수화열 조정에 관한 연구)

  • 유동수;심보길;윤치환;한민철;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.469-474
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    • 2001
  • Mass concrete is placed considering placing lifts in order to reduce thermal cracks by hydration heat. But they results in cold joint between placing lifts, which bring about the loss of strength, water tightness and undesirable appearance. Therefore, in this paper, mechanical and hydration heat of mass concrete using super retarding agent developed through previous study are investigated in order to reduce the hydration heat and place it without place lift. According to test results, placing lifts combined with normal concrete and concrete containing super retarding agent have positive effects on reducing hydration heat. Especially, the crack index by thermal stress of the concrete containing super retarding agent less than a quarter, compared to that of plain concrete without placing lifts, and less than a half, compared to that of plain concrete with placing lifts.

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Field Application of Mass Concrete Using Setting Time Difference of Super Retarding Agent for Reduction of Hydration Heat (초지연제의 응결시간차를 이용한 매스 콘크리트의 수화열 저감을 위한 현장 적용)

  • 전충근;심보길;손성운;신동안;오선교;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.11-14
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    • 2004
  • In this paper, field application of mass concrete using setting time difference of super retarding agent is reported to reduce hydration heat of concrete placed at newly constructed apartment house in Busan. Horizontal placing lift is applied. According to test results. slump and air content meets the requirement of target values. For compressive strength, it exceeds the nominal strength ordered by the costumer. Compressive strength of concrete cured in place is achieved more than the values of nominal strength at l4days. For temperature history, maximum temperature of center at top section shows 58.5$^{\circ}C$, and at bottom section, 62.6$^{\circ}C$. According to naked eye's investigation, no hydration heat crack is observed at the surface of concrete.

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