자연 및 인위적 처리방법 변화에 따른 순환잔골재의 pH저감

한천구,한민철,한상윤,Han, Cheon-Goo,Han, Min-Cheol,Han, Sang-Yoon 한국건설순환자원학회 2011 한국건설순환자원학회지 Vol.6 No.1

본 연구는 폐콘크리트로부터 발생한 성토 복토용 순환잔골재의 pH 저감을 목적으로 자연적 처리 방법 및 인위적 처리 방법을 이용하여 순환잔골재의 pH 저감특성을 비교 분석 하고자 하였는데, 그 결과를 요약하면 다음과 같다. 실내방치된 순환잔골재의 경우는 사람의 호흡 등 대기중 높은 $CO_2$농도로 인해 실외방치된 순환잔골재보다, 또한 쌓기 두께가 얇을수록 pH를 저감시킨 것으로 분석된다. 공기투과의 경우 비교적 순환잔골재의 pH저감이 효과적이었는데 이는 고압의 환풍기로 인해 순환잔골재에 원활한 $CO_2$ 공급으로 pH를 저감시킨 것으로 판단된다. 살수처리의 경우 미수화 시멘트의 수화반응을 촉진시켜 수산화칼슘을 용해시키고, 건조과정중 대기중 $CO_2$에 의한 중성화로 pH를 크게 저감시키는 것으로 나타났으며 침수처리에서는 pH 저감 효과가 미흡하였다. $CO_2$촉진의 경우 순환잔골재의 pH저감 효과가 가장 우수한 것으로 나타났는데, 이는 원활한 $CO_2$공급이 가능하기 때문인 것으로 분석된다. 이상의 실험 결과를 종합하면, pH 저감성능, 경제성 및 작업성 측면을 고려할 경우 순환잔골재 질량비 1: 0.5 비율로 살수한 다음, 강제적인 $CO_2$가스의 처리로 건습을 반복한다면 순환잔골재의 pH저감에 가장 효과적인 방법이 될 것으로 분석된다. This study is to comparatively analyze the characteristics of pH decrease in recycled fine aggregates for embankment and landfill produced from waste concrete by using natural process and artificial process. The result was as follows In case of recycled fine aggregates left outdoor, it was found that pH level was decreased if the thickness of embankment becomes thinner, or the materials left outdoors owing to high concentration of $CO_2$ in atmosphere caused by respirations of people. When the air was permeated, pH level was decreased more effectively. It was analyzed that this phenomenon was caused by efficient supply of $CO_2$ in the recycled fine aggregates owing to high-pressure ventilators. In case of water spraying treatment, sprayed water facilitated hydration of unhydrated cement to dissolve calcium hydroxides which neutralized $CO_2$ in the atmosphere during desiccation process and decrease pH level by a considerable margin. In case of Immersed treatment, decrease of pH was not sufficient. When facilitating the supply of $CO_2$, pH level of the recycled fine aggregates was decreased by the largest margin. It was analyzed that this phenomenon was caused by efficient supply of $CO_2$. From the above results, it was analyzed that the most effective method of reducing pH level of the recycled fine aggregates from the aspects of pH reduction performance, economic efficiency and workability was repeated wet-dry cycles of spraying water to the aggregates in the proportion of 1:0.5 by weight and then treating by forcefully blowing $CO_2$ gas into the aggregates.

레미콘 회수수에 안정화 처리한 콘크리트의 공학적 특성

한천구,이세현,우종환,이문환,Han, Cheon-Gu,Lee, Se-Hyeon,U, Jong-Hwan,Lee, Mun-Hwan 한국레미콘공업협회 2007 레미콘 Vol.1 No.-

배합요인에 따른 제치장 콘크리트의 표면 광택 특성

한천구,전충근,Han, Cheon-Gu,Jeon, Chung-Geun 한국레미콘공업협회 2002 레미콘 Vol.4 No.-

석회암 순환잔골재를 사용한 고강도 콘크리트의 공학적 특성

한천구,김현우,Han, Cheon-Goo,Kim, Hyun-Woo 한국건설순환자원학회 2007 한국건설순환자원학회지 Vol.3 No.1

This study investigates the engineering properties of concrete incorporating lime stone crushed fine aggregate(Ls), which has been abandoned about 20% of total production due to the low purity. Test results showed that increase of Ls had favorable fluidity and slightly decreased air content. Bleeding capacity of all specimens was not appeared as those were high strength mixture proportion, but the specimens using more Ls accelerated initial and final setting. For the mechanical properties, specimens incorporating higher ratio of Ls, overall, resulted in increase of compressive strength, and exhibited very small inclined tendency in a dynamic elasticity modulus test In addition, for the durability properties, specimens incorporating higher Ls dramatically decreased a drying shrinkage and showed similar tendency in a frost & thaw test, as well as showing no more change in an accelerated neutralization test from the beginning. In conclusion, as it was confirmed in the experimental test, the high strength concrete applying Ls did not showed any problems in the aspects of engineering properties and mostly exhibited even more excellent quality than the specimens using natural fine aggregate.

팽창재를 이용한 고성능 콘크리트의 특성과 건조수축 및 자기수축 저감에 관한 연구

한천구,홍상희,Han, Cheon-Gu,Hong, Sang-Hui 한국레미콘공업협회 1999 레미콘 Vol.1 No.-

건조수축 저감형 유동화제 및 2 중 버블시트를 사용한 콘크리트의 현장적용

한천구,오치현,신재경,Han, Cheon-Goo,Oh, Chi-Hyun,Shin, Jae-Kyung 한국건축시공학회 2007 한국건축시공학회지 Vol.7 No.1

This study investigates the filed application in Daebul Free Trade Zone applying both a flowing method using drying shrinkage-reducing superplasticizer(SRS) and an insulating curing method using double layer bubble sheet. Test results showed that fresh concrete satisfied target slump and air content. A structure adding SRS significantly decreased the total bleeding capacity and accelerated the setting time. As for the crack occurrence, the structure applying the flowing method and double bubble sheets simultaneously exhibited the most favorable crack endurance, while conventional concrete showed more than 1mm size of crack in overall. In addition, a structure applying the flowing concrete method partially presented the micro crack. For the area proportion of crack occurrence, the structure using the double bubble sheets indicated 9.8%, while others applying flowing concrete method was 28%, compared with that of conventional one. For the compressive strength of specimens, standard curing specimens indicated $3{\sim}33%$ higher value than that of specimens cured besides the field construction. The specimens containing SRS improved the strength of $2{\sim}6MPa$, which is $10{\sim}22%$ higher than that of conventional concrete.

레미콘 품질시험 및 검사

한천구,Han, Cheon-Gu 한국건축구조기술사회 2003 건축구조 Vol.10 No.4

ERCO 혼입시기 및 혼입율 변화가 HPFRCC의 자기수축저감 및 기초적 특성에 미치는 영향

한천구,이제현,Han, Cheon-Goo,Lee, Je-Hyun 한국건축시공학회 2018 한국건축시공학회지 Vol.18 No.4

전 세계적으로 폭발성 물질 사용 증가와 폭탄테러 등으로 인명 및 재산 피해가 증가하고 있는 추세이다. 이에 중요 건축물이나 군사시설에 방호 방폭 성능을 향상시킬 목적으로 섬유보강 고성능 시멘트 복합체(HPFRCC)에 대한 연구가 진행되고 있다. 그러나, HPFRCC의 자기수축 문제를 해결하기 위해 ERCO를 혼입하게 되면 높은 점성 및 지방분의 시멘트 알칼리와의 조기반응으로 유동성, 공기량 및 강도 등 품질저하의 문제점이 발생한다. 이에 본 연구에서는 기존에 도출된 HPFRCC의 최적 배합에 ERCO 혼입시기 및 혼입율 변화에 따른 HPFRCC의 자기수축저감 및 기초적 특성에 대해 분석하였다. 그 결과 모르타르 믹싱완료 후 ERCO를 0.5% 혼입하는 후혼입 방법이 유동성, 강도 및 자기수축저감 등의 HPFRCC의 품질 향상에 가장 효과적인 것으로 밝혀졌다. For the entire world, due to the increased risks of explosion and terrorisms, damages on human life and properties have been increased. Regarding this issue, research on high performance fiber reinforced cementitious composite (HPFRCC) with the protecting performance for the building structures or military facilities against explosion or bombing has been increased (important). Among a series of the research, using emulsified refined cooking oil(ERCO) to reduce the autogenous shrinkage may cause some adverse effect on performance of the mixture such as increased viscosity, decreased fluidity, air content, and strength. Hence, in this research, based on the optimum design of HPFRCC induced by previous research, the influence of ERCO adding timing and dosage on autogenous shrinkage and fundamental properties were analyzed. As a result, it was revealed that 0.5% of ERCO should be added right after the mixing is most effective for the quality of HPFRCC such as fluidity, strength development and autogenous shrinkage reducing.

플라이 애시의 치환범위 상향을 위한 콘크리트의 기초적 특성 분석

한천구,박용규,Han, Cheon-Goo,Park, Yong-Kyu 한국건설순환자원학회 2011 한국건설순환자원학회지 Vol.6 No.2

본 연구는 플라이 애시의 치환범위 상향에 따른 콘크리트의 제반 특성을 분석하여 추후 성능 향상을 위한 기초자료로 제공하기 위해 플라이 애시의 치환범위 0-40 % 및 양생 온도 $5-35^{\circ}C$에 따른 기초적 특성을 분석하였다. 그 결과 유동성은 FA의 증가에 따라 비례적으로 증가하였으나, 공기량은 감소하였다. 응결시간은 치환율 증가 및 저온일수록 지연되는 특성을 나타냈으며, 간이단열온도이력은 FA 치환율이 40 %까지 증가함에 따라 최고온도는 $8^{\circ}C$정도 낮아졌고, 최고온도 도달시간은 13시간 정도 지연되는 것을 알 수 있었다. FA 치환 상향에 따른 압축강도는 양생온도가 높을수록 플레인 대비 강도증진성이 향상됨을 알 수 있었다. 중성화의 경우는 FA 치환율이 증가할수록 깊이가 점차 커지는 것을 알 수 있어 중성화 대책에 대한 지속적인 연구가 필요할 것으로 판단되었다. In this study, increasing the range of replacement rate of FA with concrete properties were analyzed to provide basic data of FA replacement 0-40 % and curing temperature $5-35^{\circ}C$ range. As a result of the increased fluidity in proportion to the increase in FA, but decreased air. Setting time delayed at replacement rate increases and low temperature, simple insulation temperature history of the FA up to 40 % replacement rate increases the maximum temperature was low $8^{\circ}C$, the highest temperature reaching time delay of 13 hours. FA replacement up stream of the curing temperature, compressive strength compared to the higher plane, it was found that improved strength development. In carbonation tests with increasing the replacement ratio of FA carbonation depth was increased. Therefore, continued research on carbonation measures was to be necessary.

고 분말도 고로슬래그미분말 혼합재(HBS)를 활용한 고성능콘크리트의 내구성 평가

한천구,김종백,Han, Cheon-Goo,Kim, Jong-Baek 대한건축학회 2011 대한건축학회논문집 Vol.27 No.11

This paper is investigate the effect of high blaine blast furnace slag powder(HBS) on the durability of high performance concrete. The use of HBS requires an increase in dosages of superplasticizer by as much as 0.1~0.2 % and makes the concrete satisfied the target slump flow and air contents. An increase in HBS resulted in an increase of compressive strength due to latent hydraulic reaction. Coefficient of chloride diffusion, sulfate resistance and freeze thaw test results showed improved performance when HBS was incorporated. the use of HBS decreased peak temperature based on semi adiabatic temperature test. hence, it is confirmed that the addition of HBS improved strength and durability.