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粉末度가 다른 石灰石 微粉末과 鑛物質 混和材를 使用한 콘크리트의 特性
박조범,이문환,류득현 대한건축학회 2006 大韓建築學會論文集 : 構造系 Vol.22 No.10
Many studies on the improvement of performance of concrete which is main construction material are conducted to the growth of construction technology, and there have recently been attempts to improve the performance of concrete using various admixtures. In this study, in order to use limestone powder which is currently used in various fields as admixtures for concrete, blast furnace slag and fly ash were used with limestone powder also. The properties of concrete using limestone powder are evaluated to use 3 kinds of fineness. The results of concrete experiment using limestone powder with blast furnace slag and fly ash are as follows.(1) As the usage of limestone powder was increased, the fluidity of concrete improved and it was found that the mixture which used blast furnace slag increased slump and air content, and change of elapsed time more than the mixture using fly ash. (2) The unit weight content and ultrasonic pulse of concrete using limestone powder either decreased or was similar to basic mixture. So it is judged that limestone powder was filled with porosity of concrete, and thus that the air content of concrete decreased relatively by filling of limestone powder. (3) The compressive strength using limestone powder was similar to basic mixture at an early age, but as the usage of limestone powder increases, the compressive strength decreased on days 28 and 91, and the rate of strength decrease was lower as the fineness of limestone powder was higher.Therefore, the concrete using limestone powder and blast furnace slag powder has a significant effect on the improvement of fluidity, and the rate of strength decrease of concrete using high fineness of limestone powder was lower. When the limestone powder is used for concrete with mineral admixture, it was more effective if used with blast furnace slag than with fly ash.
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부순 모래의 품질 특성이 혼합 잔골재 콘크리트에 미치는 영향
박조범,이문환,류득현 대한건축학회 2007 大韓建築學會論文集 : 構造系 Vol.23 No.8
As the shortage of natural & good qualities aggregate for concrete, so the development of alternative aggregate is demanded progressively. In this study, in order to use positively crushed sand for concrete, the experiment was progressed by mixed use of crushed sand and sea sand. The crushed sand was classified 4 kinds according to dosage method of raw ore and density based on the survey of origin place of crushed sand in Seoul metropolitan district. The results of qualities of crushed sand and properties of concrete using mixed fine aggregate are as follows.(1) The qualities of crushed sand were not highly different each other except for the amount of fine particles and solid volume ratio for shape determination, and the whole properties of crushed sand were satisfied with Korean Industrial Standards except for solid volume ratio for shape determination, and the amount of fine particles of sand differed highly. The density was proportioned to the amount of fine particles of crushed sand. (2) The slump and air content of concrete using mixed fine aggregate were lower than basis mix, as the substitute ratio of crushed sand was increased, so it is judged that the workability of concrete have more influence on density of crushed sand than dosage method of raw ore. (3) The compressive strength of concrete showed on the contrary with workability, that is, as slump and air content of concrete decreased, the strength of concrete increased. Accordingly the relation to workability and strength were in inverse proportion to irrespective of kinds and substitute ratio of crushed sand.Therefore, the properties of concrete using mixed fine aggregate were more influenced on density rather than dosage method of raw ore. In conclusion, it is very important not only to use crushed sand having low density, but also to control fine particles and solid volume ratio for shape determination of high density crushed sand.
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박조범,류득현,서치호,Park, Cho-Bum,Ryu, Deuk-Hyun,Seo, Chee-Ho 대한건축학회 2012 대한건축학회논문집 Vol.28 No.3
In this study, to reduce carbon dioxide caused global warming, it attempts to manufacture high volume mineral admixture (HVMA) concrete using large content of by-products blast furnace slag and fly ash, and 10 % of cement occurred carbon dioxide. As compressive strength of HVMA concrete is lower, the concrete experiment was performed using inorganic additives, an inorganic additives of CSA, anhydrous gypsum and calcium oxide, for strength increase of normal concrete degree. At the slump of concrete, CSA 1 % series was not showed loss of change after 1 hour, but CSA 2 % series showed significant loss of change after a hour. And air content of concrete was not change between initial and 1 hour later, so additives was not affect air content. Compressive strength of 28 days was measured 23.4~30.7 MPa at CSA 1 % and range of 25.4~39.1 MPa at CSA 2 %, it increased according to usage of CSA and anhydrous gypsum, but it did not show significant changes about use of calcium oxide. Elastic modulus of 28 days was measured 27.4~29.5 GPa at CSA 1 % and range of 27.2~32.0 GPa at CSA 2 %, and its range of change according to additives were lower compared to compressive strength. Considering fluidity and mechanical properties of concrete, it is judged that optimum combination ratio of additives for performance revelation of HVMA concrete at normal concrete area was CSA is 1 %, and anhydrous gypsum and calcium oxide is 2~4 % respectively. Therefore, HVMA concrete made by only 10 % of cement and a little inorganic additives is expected that reduce carbon dioxide at concrete in manufacturing field and match government policy of low carbon green growth.
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석탄재 재활용 경량 골재를 사용한 콘크리트의 역학적 특성
박조범,조현태,김용혁,류득현 한국콘크리트학회 2019 콘크리트학회논문집 Vol.31 No.2
As the usage of coal ash generated from the thermal power plant is very limited, so a large amount of coal ash is discarded. In case of coal ash is molded and firing together with clay, it is possible to produce lightweight aggregate suitable for Korean Standards. The result of concrete experiment which is lightweight aggregate was mixed with natural fine aggregate, as the lightweight aggregate replacement ratio increased, since the adsorbed amount of water was smaller, the fluidity of fresh concrete was secured. The compressive strength of lightweight concrete decreased as w/b and lightweight aggregate usage increased, but compressive strength of lightweight aggregate 45 % series decreased as aggregate separation occurred. So it is considered important to secure the fluidity of fresh concrete. The elastic modulus was measured at the same tendency to compressive strength, and its range was narrower than compressive strength. And thermal conductivity was lower as increase of lightweight aggregate, but it increased according to age. Especially, the unit weight of lightweight concrete in experiment is measured higher than mix design value, so a solution to this problem of unit weight is required.
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부순 모래의 품질 특성이 혼합 잔골재 콘크리트에 미치는 영향
박조범,이문환,류득현 大韓建築學會 2007 大韓建築學會論文集 : 構造系 Vol. No.
<P>As the shortage of natural & good qualities aggregate for concrete, so the development of alternative aggregate is demanded progressively. In this study, in order to use positively crushed sand for concrete, the experiment was progressed by mixed use of crushed sand and sea sand. The crushed sand was classified 4 kinds according to dosage method of raw ore and density based on the survey of origin place of crushed sand in Seoul metropolitan district. The results of qualities of crushed sand and properties of concrete using mixed fine aggregate are as follows.</P><P> (1) The qualities of crushed sand were not highly different each other except for the amount of fine particles and solid volume ratio for shape determination, and the whole properties of crushed sand were satisfied with Korean Industrial Standards except for solid volume ratio for shape determination, and the amount of fine particles of sand differed highly. The density was proportioned to the amount of fine particles of crushed sand. (2) The slump and air content of concrete using mixed fine aggregate were lower than basis mix, as the substitute ratio of crushed sand was increased, so it is judged that the workability of concrete have more influence on density of crushed sand than dosage method of raw ore. (3) The compressive strength of concrete showed on the contrary with workability, that is, as slump and air content of concrete decreased, the strength of concrete increased. Accordingly the relation to workability and strength were in inverse proportion to irrespective of kinds and substitute ratio of crushed sand.</P><P> Therefore, the properties of concrete using mixed fine aggregate were more influenced on density rather than dosage method of raw ore. In conclusion, it is very important not only to use crushed sand having low density, but also to control fine particles and solid volume ratio for shape determination of high density crushed sand.</P>
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박조범(Park, Cho-Bum),박창건(Park, Chang-Gun),백철우(Back, Chul-Woo),최성우(Choi, Sung-Woo),류득현(Ryu, Deug-Hyun) 한국콘크리트학회 2021 한국콘크리트학회 학술대회 논문집 Vol.33 No.2
콘크리트 공사에서 과도한 진동다짐에 의한 굵은 골재의 분리는 배합과 재령에 관계없이 강도발현에는 큰 영향이 없었다. 굵은 골재가 분리된 시험체의 압축강도는 유사하였으며, 탄성계수는 진동다짐 시험체가 101 %에서 113 % 까지 증가하였다. 진동다짐에 의한 굳은 콘크리트에서의 영향을 분석하기 위해서는 본 연구의 결과보다 다양한 배합인자와 진동조건에서 분석하여야 할 것으로 판단된다. The separation of aggregates by excessive vibration in concrete construction didn‘t significantly affect compressive strength regardless of mixtures and age. The compressive strength of specimen is separated aggregate was similar, and elastic modulus increased from 101 % to 113 %. In order to analyze effect of vibration compacting on hardened concrete, it is judged that it should be analyzed under various factors and vibration conditions rather than results of this study.
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박조범(Park Cho-Bum),최성우(Choi Sung-Woo),김경찬(Kim Kyung-Chan),지석원(Ji Suk-Won),류득현(Ryu Deug-Hyun) 한국콘크리트학회 2021 한국콘크리트학회 학술대회 논문집 Vol.33 No.1
강섬유 콘크리트는 철근콘크리트공사에서 철근을 사용하지 않거나 줄일 수 있어 생산성 향상에 큰 장점이 있다. 휨 하중에 대한 저항성을 높이기 위해서는 인장강도가 높은 강섬유를 사용하는 것이 유리하며, 인장강도 1,500 MPa이 1,000 MPa보다 휨 하중이 약 6.20~32.1 % 정도 높았고, 강섬유 사용량이 20, 40kg/m3보다는 80kg/m3를 사용하여야 그 성능이 더욱 큰 것으로 나타났다. Steel fiber concrete has a great advantage in improving productivity because it cannot use or reduce rebar in reinforced concrete construction. To increase the resistance to bending loads, it is benefit to use high tensile strength steel fiber, with a tensile strength of 1,500 MPa about 6.20~32.1 % higher flexural load than 1,000 MPa, and 80 kg/m3 greater performance than 20, 40 kg/m3.
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