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잔골재의 미립분 보충재로 순환골재 미분말을 활용하는 모르타르의 기초적 특성
한인덕 ( In-deok Han ),장명훈 ( Myunghoun Jang ) 조선대학교 공학기술연구원 2020 공학기술논문지 Vol.13 No.4
In order to improve the performance of cement mortar using combined sand of crushed and sea sands, this study analyzed its fundamental properties in accordance with replacement by recycled aggregate powder. The results showed that for binary aggregate with crushed and sea sands in a 6 to 4 ratio, the standard gradation was satisfied with replacement by less than 7.5% of recycled aggregate powder. Furthermore, as the replacement ratio of the recycled aggregate powder was increased, fluidity decreased and air content increased. Meanwhile, with replacement of less than 10% by the recycled aggregate powder, compressive strength increased 10 to 20% under the conditions of this research. Overall, it was determined that by replacement of 2.5% of recycled aggregate powder in binary aggregate with crushed and sea sand with poor gradation, optimum results could be obtained for satisfying the standard gradation and improving the fundamental properties of the cement mortar. It is necessary to evaluate the possibility of applying this result to concrete and actual structures.
한인덕 ( In-deok Han ),정명주 ( Myung-joo Jeong ),장명훈 ( Myunghoun Jang ) 조선대학교 공학기술연구원 2021 공학기술논문지 Vol.14 No.4
Urban concentration of the population is causing a decrease in the population of underdeveloped areas, and the number of closed schools in rural areas is also increasing because of a decrease in the number of students. Efforts to use closed schools as cultural facilities are being made, but they are still insufficient. Since the same problems also occur in Jeju, we would like to investigate the current status, identify problems, and propose more efficient and active utilization plans based on cases of closed schools currently in use. As a result of understanding the use status of existing closed elementary schools, we determined that welfare facilities for the elderly and club centers can be alternative uses for closed schools. Welfare facilities for the elderly provide education, healing, rest, and jobs for the silver generation. The club center is a space where people with the same hobby can gather and help each other.
광물질 혼화재의 치환율 변화가 고유동 콘크리트의 특성에 미치는 영향
한인덕(Han, In-Deok) 대한건축학회 2019 大韓建築學會論文集 : 構造系 Vol.35 No.12
본 연구는 물결합재비 40 %인 일반강도 영역에서 FA, BS 및 FA+BS인 광물질 혼화재의 0~30 %의 치환율 변화가 분체계 고유동 콘크리트의 재료분리 저항성 등 제반 특성에 미치는 영향에 대하여 분석하였다. 특히 고유동 콘크리트에서 밀도가 작은 분체의 치환율을 증가시킬 경우 액상 콘크리트의 점성저하로 재료분리가 증대될 수 있지 않은지, 또한 J-ring시험으로 철근 장애부에 의한 재료분리 정도에는 영향을 미치지 않을지 등 제반특성을 검토분석하였다. 실험연구 결과 Normal 시험의 경우는 기존의 이론과 같이 광물질 혼화재의 치환율이 증가할수록 레올로지적 측면의 점성증가로 재료분리가 방지되었다. 단, J-ring를 이용한 시험의 경우는 액상중 밀도저하로 양호하게 골재를 끌고 철근사이를 통과하지 못해 재료분리 방지에 큰 역할을 하지 못함을 알 수 있었다. The aim of the research is to evaluate the influence of various replacing ratios of supplementary cementitious materials(SCMs) such as fly ash(FA), blast furnace slag(BS), and both FA and BS on general properties including segregation resistance as a powder based high fluidity concrete of normal strength grade with water-to-cement ratio 0.40. Specifically, by replacing the SCMs with low density powders, it was assessed that the decreased segregation resistance due to the decreased viscosity by J-ring test. As a result of the experiment, from the general test, the mixtures with SCMs showed increased segregation resistance by increased viscosity as the references, while some segregation was shown from J-ring test due to the decreased density of fresh state mixture related with the capacity of delivering coarse aggregate.
이혁주 ( Lee Hyuk-ju ),한준희 ( Han Jun-hui ),이재진 ( Lee Jae-jin ),한동엽 ( Han Dong-yeop ),한인덕 ( Han In-duck ),한민철 ( Han Min-choel ) 한국건축시공학회 2018 한국건축시공학회 학술발표대회 논문집 Vol.18 No.1
There are three types of high fluidity concrete: powder based, VMA based, and combined. In the case of the powder based high fluidity concrete mixture, according to the textbook, increased viscosity due to the replaced fly ash can prevent segregation of coarse aggregate. On the other hand, decreased density of the powder due to the fly ash replacement can causes segregation but there is no report on this issue. Therefore, in this research, the segregation resistance and segregation evaluation method for powder based high fluid concrete mixture are evaluated. As a result, with increased replacing ration of supplementary materials, EIS value was decreased and apparently segregation resistance was increased. However, from the compressive strength evaluation depending on height of the cylindrical specimen, it was confirmed that the different of strength difference between top and bottom part of the specimen. Thus, following research regarding vertical segregation should be studied.
경화된 분체계 고유동 콘크리트의 혼화재 치환 변화에 따른 재료분리 저항성 분석
이혁주 ( Lee Hyuk-ju ),최윤호 ( Choi Yoon-ho ),한준희 ( Han Jun-hui ),한인덕 ( Han In-deok ),한동엽 ( Han Dong-yeop ),한민철 ( Han Min-cheol ) 한국건축시공학회 2019 한국건축시공학회 학술발표대회 논문집 Vol.19 No.1
The use of high fluidity concrete has been added in recent construction work. In this study, we analyzed segregation resistance due to admixture substitution of the system high fluidity concrete that was hardened. The research results show that the resistance to segregation at the time of admixture replacement is improved. The best results were shown with a ternary system mixed like FA and BS.
한인덕,김두성,장명훈,Han, In-Deok,Kim, Doo-Seong,Jang, Myunghoun 한국건축시공학회 2023 한국건축시공학회지 Vol.23 No.4
Buildings that have been long neglected can suffer severe durability reduction due to factors such as rebar rust and concrete quality deterioration resulting from exposure to outside air. Furthermore, the issues associated with these suspended buildings, including safety accidents, social crimes, and environmental pollution, are becoming increasingly serious. This study investigates the current status of these buildings in the Jeju area, identifies the problems, and examines the durability of the structure in a specific location to assess the possibility of future use. Aesthetic surveys(visual and slope inspections) as well as non-destructive tests(compressive strength tests, neutralization tests, and rebar detection tests) were conducted to assess durability. The analysis revealed that the structure maintained satisfactory durability and the building's condition was good in comparison to the years of neglect.
한천구(Han, Cheon-Goo),한인덕(Han, In-Deok) 대한건축학회 2015 大韓建築學會論文集 : 構造系 Vol.31 No.7
Since the currently used segregation evaluation method is quantitative method based on the experience of operator, it has had many difficulties to adopt for practice. In this research, as a solution of this problem, new workability performance evaluation method was suggested using the performance levels based on the evaluation index of segregation for normal concrete (EISN) quantified by the maximum-to-minimum ratio of the flow of slumped concrete by the slump test. As the results of the experiment, when the range of the slump value was 150 to 230 mm, (slump flow value was 300 to 450 mm)the evaluation method was valid. Namely, as a base of 1.09 EISN, lower and higher ranges were determined as a “good” and “segregation”, respectively, and further performance leveling was suggested with 1.06 ? 1.09 for III level, 1.03 ? 1.06 for II level, and1.00 ? 1.03 for I level within the “good” range. Within the good conditions of concrete, the categorized performance levels were suggested with level I, II, and III for 1.00 - 1.03, 1.03 - 1.06, and 1.06 - 1.09, respectively.
잔골재율 및 단위수량 변화에 따른 고강도 콘크리트의 품질특성
한천구(Han, Cheon-Goo),한인덕(Han, In-Deok) 대한건축학회 2015 大韓建築學會論文集 : 構造系 Vol.31 No.9
Although water-to-cement ratio is the main factor of determining the compressive strength of the concrete, sand-to-aggregate ratio, and unit water content dominate segregation resistance and target slump of the concrete, respectively. Therefore, in this research, to suggest a fundamental data on sand-to-aggregate ratio and unit water content for mix design of high strength concrete, fundamental properties of the high strength concrete of 30 % water-to-cement ratio were evaluated depending on the various sand-to-aggregate ratio and unit water content. As a result of the experiment, for fresh state concrete properties, as the sand-to-aggregate ratio was increased, slump, slump flow, and air content were decreased, and as the unit water content was increased, slump, slump flow, and air content were increased. Based on the 180 mm of slump, each slump and slump flow measurements deduced favorable performances at lower and higher than this value, respectively. In segregation aspect, about 45 % of sand-to-aggregate ratio was good and under this conditions, it was good to control the superplasticizer dosage and unit water content. Furthermore, to achieve better compressive strength, under the 45 or 50 % of sand to aggregate ratio, low unit water content of 165 kg/m<SUP>3</SUP> showedmaximumvalueofcompressivestrength.
김두성 ( Kim Doo-seong ),한인덕 ( Han In-deok ),장명훈 ( Jang Myunghoun ) 한국건축시공학회 2023 한국건축시공학회 학술발표대회 논문집 Vol.23 No.1
Neglected buildings for long period can seriously reduce the durability of the building due to rust in rebars and deterioration in concrete quality due to exposure to outside air, and the seriousness of suspended buildings such as safety accidents and social crimes is emerging due to poor management. In this study, various problems such as the occurrence of safety accidents were analyzed through a fact-finding survey of buildings that have not been maintained due to long-term neglect in all areas of Jeju. In order to reuse a building that has been discontinued, the safety of the building structure itself must be checked. After securing safety through durability investigation, construction should be resumed or converted into a normal building through re-purposing, dismantling, remodeling, etc.