• 제목/요약/키워드: Frost damage at early age

검색결과 35건 처리시간 0.022초

열선 전력 용량에 따른 극한온도 조건에서의 콘크리트 온도이력 특성 (Temperature History of Concrete exposed to Extremely Cold Weather with the Variation of Capacity of Heating Coil)

  • 정은봉;정상현;안상구;고경택;한민철;한천구
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2012년도 추계 학술논문 발표대회
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    • pp.51-53
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    • 2012
  • This paper is to report the results of mock-up test for concrete during severe cold weather. The temperature is fixed at -20℃. The mock-up specimens were fabricated simulating slab, wall and column. Heating coil with different heat capacity with 5 W and 15 W were embedded at slab specimen. Test results revealed that at -20℃, temperature dropped below 0℃ since around 70 hours. It takes 7 days to gain 45°D·D of maturity for avoiding frost damage at early age.

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양생온도 -10℃에서 거푸집 재료 변화에 따른 콘크리트의 압축강도 특성 (Compressive Strength Properties of Concrete by the Form Material Change at 10 below Zero)

  • 최시현;이한승
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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    • pp.107-108
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    • 2016
  • When the construction in a low temperature, the concrete performance is deteriorated by frost damage at early age. In this study, the form utilizing heating sheet and insulation is measured the performance to prevent frost damage at 10 below zero. It produced five types of the form and to measure the temperature history and compressive strength. At first, form attached heating sheet showed the highest temperature. But the form attached vacuum insulation showed the highest temperature ever since 12hours. In the case of compressive strength, the form attached heating sheet + isopink(polystyrene foam board) showed the highest compressive strength. It was followed by vacuum insulation. As a result, the form utilizing insulation and heating sheet helped to prevent frost damage.

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열선 매입과 열선 및 버블시트 조합의 개량형 버블시트를 포설한 슬래브 콘크리트의 온도이력 특성 (Temperature History of the Slab Concrete applying Revised Bubble Sheet with Heating Cable)

  • 정은봉;안상구;정상현;고경택;한민철;한천구
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2013년도 추계 학술논문 발표대회
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    • pp.23-25
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    • 2013
  • In this study, the results are compared with the case of the concrete with embedded heating wire to verify the performance of the IB made in order to improve the workability and affordability, and to determine the effectiveness of early frost damage prevention. The IB was made using the 5W heating wire and layed on the upper surface of the concrete. The temperature was reduced to below 0℃ approximately within 24 hours, then approached the external temperature thereafter. On the other hand, when the 20W heating wire was used to make the IB and applied the same way, the temperature remained around -2 to 3℃ on the average even through the temperature was reduced to below 0℃, due to the heating wire with relatively large heating capacity. It appeared to reach 85% of the direct heating by embedding the heating wire relatively deeper in the concrete. However, it was determined that using the IB made with the 20W heating wire will prevent the early frost damage to some degree in -10℃.

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한중콘크리트 시공시 표면 단열재 변화에 따른 콘크리트의 온도이력 특성 (The Properties of Temperature History of Concrete with Surface Insulating Material in Cold Weather Concreting)

  • 문학용;신동안;김경민;김기철;오선교;한천구
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2003년도 학술.기술논문발표회
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    • pp.7-11
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    • 2003
  • This study investigate the hydration heat history with variation of surface insulating material in cold weather concreting. According to the results, the temperature of concrete lowers below zero in 24hours, so early frost damage occurs in the case of exposure and 1 fold bubble sheet, but the lowest temperature keeps above zero, so a adiabatic effect is very favorable in the case of double bubble sheet and 부직포. Compressive strength of core specimen at 7 and 28 days is highest In the case of double bubble sheet and 부직포. But, considering convenience of construction and economical efficiency, it is thought that the most effective surface insulating material is 1 fold bubble sheet +blanket.

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The Effect of Heat Curing Methods on the Protection against Frost Damage at Early Age of the Concrete Under Extremely Cold Climate

  • Jung, Eun-Bong;Shin, Hyun-Sup;Han, Min-Cheol
    • 한국건축시공학회지
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    • 제13권6호
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    • pp.513-521
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    • 2013
  • This study aimed to examine whether heat curing methods of concrete subjected to $-10^{\circ}C$ could be effective by varying the combination of heating cable and surface heat insulations. Three different concrete specimens incorporating 30% fly ash with 50% W/B were fabricated to simulate wall, column and slab members with dimensions of $1600{\times}800{\times}200$ mm for slab, $800{\times}600{\times}200$ mm for wall and $800{\times}800{\times}800$ mm for column. For heat curing combinations, Type-1 specimens applied PE film for slab, plywood for wall and column curing. Type-2 specimens applied double layer bubble sheet (2LB) and heating coil for slab, and 50 mm styrofoam for wall and column curing. Type-3 specimen applied 2LB for slab, electrical heating mat for wall and column inside heating enclosure. The test results revealed that the temperature of Type 1 specimen dropped below $0^{\circ}C$ beginning at 48 hours after placement due to its poor heat insulating capability. Type 2 and 3 specimens maintained a temperature of around $5{\sim}10^{\circ}C$ after placement due to favorable heat insulating and thermal resistance.

저온 환경하에서의 혼화재 종류 및 대체율에 따른 콘크리트의 강도발현특성에 관한 연구 (An Experimental Study on the Property of Strength for kinds and Replacement ratio of Admixture under Low Temperature)

  • 김호수;전순제;반성수;최성우;류득현
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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    • pp.687-690
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    • 2005
  • Recently, to consider financial and constructive aspect, usage of Admixture, like Blast- Furnace Slag and Fly-Ash, are increased. These mineral admixtures, a by-product of steel industry, have many advantage, to reduce the heat of hydration, increase in ultimate strength, improve workability and etc. But it also reduces early-age strength, so it is prevented from using of Blast-Furnace Slag at cold-weather-concrete. In this study, for the purpose of increasing usage of mineral admixtures, like Blast-Furnace Slag and Fly ash, it is investigated the strength properties of concrete subjected to under low temperature According to this study, if early curing is carried out before having frost damage, the strength of concrete, subjected to frost damage, is recovered. And to consider increasing effect of strength, it is more effective to use of mineral admixtures, especially to use blast furance slag.

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초기동해를 입은 콘크리트의 압축강도에 미치는 영향인자에 관한 연구 (A Study of Influencing Factors on Compressive Strength of Concrete Frozen at Early Ages)

  • 배수원;김진근;권기주;정원섭
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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    • pp.527-532
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    • 2003
  • When fresh concrete is exposed to sufficiently low temperature, the free water in the concrete is cooled below its freezing point and transforms into ice, which causes decrease in compressive strength of concrete. Of the many influencing factors on the loss of compressive strength, the age of concrete at the beginning of freezing, water-cement ratio, and cement-type are significantly important. The objective of this study is to examine how the these factors affect the compressive strength of concrete frozen at early ages. The results from the tests showed that as age at the beginning of freezing is delayed and water-cement ratio is low, the loss of compressive strength decreases. In addition, concrete made with high-early-strength cement is less susceptible to frost damage than concrete made with ordinary portland cement.

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초기동해를 받은 고로슬래그 다량 혼입 콘크리트의 강도발현 및 동결융해 저항성 (Strength Development and Freeze-Thaw Resistance of Concrete Incorporating High Volume Blast-Furnace Slag Subjected to Initial Frost Damage)

  • 고경택;류금성
    • 한국건설순환자원학회논문집
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    • 제6권3호
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    • pp.79-87
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    • 2011
  • 고로슬래그를 다량으로 혼입한 콘크리트를 동절기에 시공할 경우에는 배합에 따라서 응결과 경화가 현저히 지연되어 초기동해를 받을 위험성이 높다. 따라서 이 연구에서는 동절기에 고로슬래그를 다량으로 혼입한 콘크리트가 재령 초기에 동결을 받은 경우를 상정하여 초기동해가 콘크리트의 압축강도와 동결융해 저항성에 미치는 영향을 검토하였다. 그 결과, 고로슬래그를 다량으로 혼입한 콘크리트는 초기동해를 받음으로써 압축강도와 동결융해 저항성 모두가 현저히 저하되고, 고로슬래그를 혼입하지 않은 일반콘크리트에 비해서 특히 동결융해 저항성이 크게 저하되는 것으로 나타났다.

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극저온 조건에서의 양생방법 변화에 따른 실구조체 콘크리트의 강도발현 특성 (Strength Development of Mock-up Concrete Structure subjected to Extremely Low Temperature Condition Due to Curing Methods)

  • 정은봉;정상현;안상구;고경택;한민철;한천구
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2012년도 추계 학술논문 발표대회
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    • pp.47-49
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    • 2012
  • Under this study, the characteristics of concrete intensity condition following the curing method under the extremely low temperature environment have been contemplated, and as a result, in the event of insulation + heat cable curing, the intensity and accumulated temperature accomplishment period is required for two times of requiring initial frost damage prevention than the case of heating + heat insulation curing method due to the insufficient calories supplied in general.

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시멘트 산지 및 자기발열분체 사용에 따른 모르타르 및 콘크리트의 저온에서의 압축강도성능 평가 (Evaluation on Compressive Strength of Mortar and Concrete at Early Age Using Variable Cement and Self-heating Binder)

  • 홍석범;김우재;유조형
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2016년도 추계 학술논문 발표대회
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    • pp.152-153
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    • 2016
  • In this research, we evaluate the performance for preventing frost damage at early age of mortar using variable cement and self-heating binder. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature without heat curing. We compare the compressive strength of mortar and concrete using variable cements and self-heating binder in low temperature.

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