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김한식 ( Kim Han-sic ),하정수 ( Ha Jung-soo ),이영도 ( Lee Young-do ) 한국건축시공학회 2022 한국건축시공학회 학술발표대회 논문집 Vol.22 No.2
The demand for a construction method capable of securing a safety environment and improving quality is increasing. There is a high risk of falling when working at a high place in an environment where it is difficult to secure visibility, such as an underground space, and there is a risk of falling if cement liquid waterproof materials are transferred to the top of the scaffold by manpower. In addition, when working on a high place in a poor environment, the quality uniformity of the upper part of the wall is deteriorated. In addition, as waterproof technicians gradually age and decrease, it is difficult to secure them, so it is urgent to prepare countermeasures against the shortage of waterproof technicians. Therefore, the purpose of this study is to develop cement liquid waterproof spouting construction equipment that can secure uniform quality of construction areas to prevent accidents and ensure safety of workers, improve work efficiency and quality due to improvement of work environment. The adhesion performance of the cement liquid waterproof material could be improved by about 20% in accordance with the use of the equipment.
고분말도 시멘트와 고로슬래그 미분말을 사용한 콘크리트의 강도발현 성상
김한식 ( Kim Han-sic ),하정수 ( Ha Jung-soo ),이영도 ( Lee Young-do ) 한국건축시공학회 2018 한국건축시공학회 학술발표대회 논문집 Vol.18 No.1
As part of the effort to shorten the construction period, this study examined the strength expression characteristics at the early age of concrete using high fineness cement and blast furnace slag. accordingly to provide a basic data on how to solve the problem that the initial strength is lowered.
지하주차장 슬래브 하자 저감을 위한 콘크리트 규격 및 배합설계
김한식 ( Kim Han-sic ),하정수 ( Ha Jung-soo ) 한국건축시공학회 2023 한국건축시공학회 학술발표대회 논문집 Vol.23 No.1
Concrete surfaces have weak surface strength due to bleeding and laitance, and problems such as peeling, cracking, and cracking may occur. In particular, underground parking lots can be said to be more vulnerable to peeling, breaking, and cracking if excessive loading of materials and equipment movement are not managed at the initial age after placing of concrete. Cracks, peeling, and cracking problems in slab concrete in underground parking lots of apartments can lead to leakage problems and affect finishing materials constructed on top of topping concrete, reducing the performance required for waterproof materials. Therefore, in this study, the bleeding and surface strength according to the standard of topping concrete and the use of admixture were reviewed to solve the crack, peeling, and cracking problems among the types of defects in underground parking lot slab concrete. As a result, it was derived that the optimal concrete compressive strength is 30MPa or more, and it is a reasonable performance design method to prohibit the substitution of admixtures.
김한식 ( Kim Han-sic ),하정수 ( Ha Jung-soo ),이영도 ( Lee Young-do ) 한국건축시공학회 2023 한국건축시공학회 학술발표대회 논문집 Vol.23 No.1
When primer is applied manually, adhesion performance decreases due to a decrease in primer penetration performance on the surface, and construction period delay may occur due to a long time due to a decrease in work efficiency when a large area is worked using a conventional roller. In addition, in the case of the roller method, precision work in corners and narrow spaces is not possible, so it is urgent to come up with measures to ensure uniform quality. In addition, secondary work occurs to remove fine powder from the surface before primer application, resulting in construction period delay due to the rise of the working stage. Therefore, in this study, equipment was used instead of manual work for primer work, and as a result, penetration performance and adhesion performance were improved about twice. From these results, it was confirmed that favorable results such as improving work speed, securing high quality, improving the working environment, and resolving the shortage of functional workers can be obtained.
순환 잔골재에 부착된 시멘트 페이스트의 영향에 의한 고강도 콘크리트의 물리적 특성 변화
김한식(Kim, Han-Sic),하정수(Ha, Jung-Soo),이영도(Lee, Young-Do) 대한건축학회 2022 대한건축학회논문집 Vol.38 No.2
This study is to confirm an appropriate substitution rate by evaluating the autogenous shrinkage and physical properties of high-strength concrete by supplying moisture required for hydration reaction by recycled fine aggregates containing a lot of moisture by attached cement paste. The experimental variables were the moisture content and substitution rate of the recycled fine aggregate, and the hydration temperature, length change, and compressive strength characteristics were evaluated. As moisture was supplied by recycled fine aggregates, cement paste at a low water-cement ratio was able to reduce autogenous shrinkage and continue hydration reactions. However, when the substitution rate of the recycled fine aggregate exceeds 30%, the decrease in strength was large due to the influence of the attached cement paste. From these results, it was confirmed that the decrease in strength due to the attachment cement paste was not significant and the substitution rate of the recycled fine aggregate that helps to continue the hydration reaction was 30%.