• Title/Summary/Keyword: 발열양생

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Fundamental Properties of Low-Heat Concrete According to the Mixing Rate of Super Retarding Agent (초지연제 혼입률에 따른 저발열 콘크리트의 양생온도별 기초물성평가)

  • Park, Byoung-Joo;Choi, Yoon-Ho;Hyun, seung-Yong;Kim, Jong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.06a
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    • pp.90-91
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    • 2020
  • As the construction site has become narrower recently, the importance of mass concrete is naturally being highlighted as skyscrapers become popular. However, it is not possible to install the entire volume per day if the mass concrete is installed due to the Remicon 8⦁5 system and the 52-hour workweek system. When the mass concrete base is divided into several days, cold joints occur because the consolidation of joints is not integrated due to different degree of hardening in the case of the previous layer and the next day. As a result, existing research has shown that if super retarding agent are mixed into Ready Mixed Concrete (hereinafter referred to as Remicon) using sugar as a raw material to delay the curing time of concrete, cold joints are inhibited and cracks are inhibited by reducing the initial hydration heat.

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A Study on Properties of Early Strength Development of the Concrete (콘크리트의 조기강도 발현특성에 관한 연구)

  • Kang, Chang-Woon;Lee, Jae-Sam;Kim, Jung-Sik;Sung, Yong-Hwan;Ryu, Deug-Hyun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.541-544
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    • 2008
  • Recently, due to the increase of high-rise buildings construction, many researches for making harden of concrete earlier and remove of forms faster are being performed to reduce construction period. The purpose of this study is to analysis which mixing condition and curing temperature of early strength concrete. Porperties of concrete by the different factors, such as the type of active admixtures, mineral admixtures, curing temperature, the amount of binder, etc. Through the test of concrete using the different type of admixture, PC type was more excellent than PNS type admixture. The concrete Strength remarkably will be able to confirm that decreases from temperature below 12$^{\circ}C$.

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Effect of Steam Curing on Compressive Strength of Slag Binder Concrete (증기양생이 고로슬래그 콘크리트의 압축강도에 미치는 영향)

  • Lim, Byung-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.8
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    • pp.338-343
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    • 2017
  • In this study, blast furnace slag powder was used in concrete to help reduce carbon dioxide emissions and to recycle industrial waste. Blast furnace slag powder is a byproduct of smelting pig iron and is obtained by rapidly cooling molten high-temperature blast furnace slag. The powder has been used as an admixture for cement and concrete because of its high reactivity. Using fine blast furnace slag powders in concrete can reduce hydration heat, suppress temperature increases, improve long-term strength, improve durability by increasing watertightness, and inhibit corrosion of reinforcing bars by limiting chloride ion penetration. However, it has not been used much due to its low compressive strength at an early age. Therefore, this study evaluates the effects of steam curing for increasing the initial strength development of concrete made using slag powder. The relationship between compressive strength, SEM observations, and XRD measurements was also investigated. The concrete made with 30% powder showed the best performance. The steam curing seems to affect the compressive strength by destroying the coating on the powder and by producing hydrates such as ettringite and Calcium-Silicate-Hydrate gel.

An Experimental Study on the Application in-situ of Curing Method by Planar Surface Heater for Cold Weather Concreting (전기발열시트 표면가열 양생공법의 현장적용 연구)

  • 김형래;조호규;김찬수;지남용
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2003.05a
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    • pp.19-22
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    • 2003
  • The purpose of this study is to analyze the curing effect of planar surface heater for concreting in cold weather. Some experiments were conducted to evaluate the temperature history of concrete structures cured with heating sheets. Results are as follows ; (1) The temperature of concrete showed continuously rising trend with the heating by planar surface heater under the cold environmental condition of 3~-12$^{\circ}C$. And after about 24 hours the maximum temperature of concrete was reached at 25~3$0^{\circ}C$. (2) The temperature of slab concrete heated by planar surface heater of 130W/$m^2$ was at least $25^{\circ}C$ higher than that of an exterior air, and the curing performance was much more effective than heating by hot wind machine. (3) Through the curing by planar surface heater for 48 hours, the concrete maturity of about 1.5 times to heating by hot wind machine was acquired.

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

  • Choi, Si-Hyun;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2016.05a
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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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Science Technology - 세계 1등 기술 10년간 한국 먹여 살린다

  • Kim, Hyeong-Ja
    • TTA Journal
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    • s.144
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    • pp.18-19
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    • 2012
  • 최근 지식경제부 산하 산업기술연구회가 앞으로 10년간 한국을 먹여 살릴 최고 수준의 기술 14가지를 발표했다. 산업기술연구회 산하 7개 출연연구기관은 지난해부터 매년 '세계 1등 연구과제'를 지정받아 세계 최고 수준의 성과를 내놓고 있다. 이 가운데 세계 1위를 달리고 있는 기술은 한국생산기술연구원의 '에코 알루미늄 에코 마그네슘'과 '해조류 셀룰로오스 등을 이용한 연료 생산 기술', 한국전자통신연구원의 '100배 빠른 광인터넷 기술', 한국건설기술연구원의 '세상에서 가장 긴 콘크리트 교량 기술', 한국철도기술연구원의 '콘크리트 발열 촉진 양생 기술'을 비롯해 '저심도 도시철도 시스템 기술'과 초경량 유리섬유 복합소재 전동차 대차 프레임', 한국화학연구원의 '하이브리드 나노세공체 응용 연구' 등 8가지이다. 이 중 몇 가지 기술을 살펴보자.

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Effect of Curing Sheet Conbined with Bubble Sheet and Heat generating Materias under Light Source on Surface Temperature of Cement Mortar (광발열소재와 버블시트를 조합한 양생시트가 모르타르의 표면온도 이력에 미치는 영향)

  • Kim, Su-Hoo;Hu, Win-Yao;Beak, Sung-Jin;Han, Jun-Hui;Kim, Jong;Han, Min-Cheol
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.04a
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    • pp.160-161
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    • 2022
  • This study is to investigate the temperature history over time of the cement mortar to confirm the bubble sheet insulation effect using the heat generat sheet. As a result of the experiment, it was confirmed that the heating effect was 6℃ higher on average than other types of sheets when the heating sheet is attached on the bottom of the double layered bubble sheet. For future research, it is planned to verify the heating performance by using the heating sheet under the same environmental conditions as the heating performance will be verified.

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Mathematical Modeling of Degree of Hydration and Adiabatic Temperature Rise (콘크리트의 수화도 및 단열온도상승량 예측모델 개발)

  • 차수원
    • Journal of the Korea Concrete Institute
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    • v.14 no.1
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    • pp.118-125
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    • 2002
  • Hydration is the main reason for the growth of the material properties. An exact parameter to control the chemical and physical process is not the time, but the degree of hydration. Therefore, it is reasonable that development of all material properties and the formation of microstructure should be formulated in terms of degree of hydration. Mathematical formulation of degree of hydration is based on combination of reaction rate functions. The effect of moisture conditions as well as temperature on the rate of reaction is considered in the degree of hydration model. This effect is subdivided into two contributions: water shortage and water distribution. The former is associated with the effect of W/C ratio on the progress of hydration. The water needed for progress of hydration do not exist and there is not enough space for the reaction products to form. The tatter is associated with the effect of free capillary water distribution in the pore system. Physically absorption layer does not contribute to progress of hydration and only free water is available for further hydration. In this study, the effects of chemical composition of cement, W/C ratio, temperature, and moisture conditions on the degree of hydration are considered. Parameters that can be used to indicate or approximate the real degree of hydration are liberated heat of hydration, amount of chemically bound water, and chemical shrinkage, etc. Thus, the degree of heat liberation and adiabatic temperature rise could be determined by prediction of degree of hydration.

Compressive Strength Generation Properties of Concrete using a Large Amount of Industrial Byproduct (산업부산물을 다량 사용한 콘크리트의 압축강도 발현 특성 검토)

  • Kim, Yong-Ro;Song, Young-Chan;Park, Jong-Ho;Jeong, Yong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.2
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    • pp.67-73
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    • 2011
  • In this study, it was investigated compressive strength generation of concrete using high volume mineral admixture obtaining fundamental data for the application of concrete structure in construction field. For this, it was evaluated compressive strength with unit binder contents($310{\sim}410kg/m^3$), replacement ratio of mineral admixture(70~90%), unit water contents($140{\sim}150kg/m^3$) and curing temperature in the normal strength range. Also, after producing mock-up structure, hydration heat and compressive strength generation was evaluated to examine properties in the concrete member. In case of concrete using a large amount of industrial byproducts which was reviewed in this study, it is possible to secure compressive strength more than 24MPa at age 28days with about $13^{\circ}C$ ambient temperature of curing condition and that is considered to be applied to structure at construction site.

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Setting Behavior of Polystyrene Mortars with Elapsed Curing Time (폴리스티렌 모르타르의 양생재령에 따른 경화거동)

  • Choi Nak-Woon;Kim Han-Sang
    • Journal of the Korea Concrete Institute
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    • v.16 no.1 s.79
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    • pp.54-60
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    • 2004
  • This study deals with the setting behavior of polystyrene mortars using waste expanded polystyrene(EPS) solution-based binders. The binders for polystyrene mortars are made by mixing crosslinking agent with EPS solutions prepared by dissolving EPS in styrene. Polystyrene mortars are prepared with various EPS concentrations of EPS solutions and crosslinking agent contents, subjected to a dry curing, and tested for working life, peak exotherm temperature and 10h-length change. From the test results, He working lives of polystyrene mortars are shortened with raising EPS concentration of EPS solution and crosslinking agent content. Low-shrinkage or non-shrinkage polystyrene mortars could be obtained by adjusting EPS concentration of EPS solution and crosslinking agent content.