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혼화재 종류에 따른 PSC 교량용 그라우트의 재료특성 평가
원천봉(Yuan Tianfeng),류두열(Yoo Doo-Yeol),고경택(Koh Kyung-Taek ),윤영수(Yoon Young-Soo) 한국방재학회 2018 한국방재학회논문집 Vol.18 No.2
본 연구에서는 플라이 애시(FA), 보통 실리카퓸(SF)과 지르코늄 실라카퓸(Zr)을 사용한 PSC 그라우트의 재료특성을 평가하였다. 실험결과, FA와 Zr을 사용한 그라우트 배합들은 적은 감수제 혼입량에서도 우수한 유동성을 나타냈으나, 계획된 시간에 측정된 블리딩 및 체적변화량은 증가하였다. 압축강도는 모든 그라우트 배합들에서 재령 7, 28일에 우수한 강도 발현을 나타났고, 3성분계 그라우트 배합들은 2성분계 그라우트보다 우수한 거동을 보였다. 또한 3성분계 그라우트 배합들을 수축저감제(SRA)와 팽창재(EA)를 병용하여 자기수축 특성을 평가한 결과, SRA와 EA를 사용함으로써 자기수축을 47~80% 저감하였으며, SF을 사용한 그라우트 배합에서 효과적인 수축저감 특성을 나타냈다. This experimental study investigates material properties of prestressed concrete (PSC) grout depend on the combination of fly ash (FA), silica fume (SF) and zirconia silica fume (Zr). Based on the test results, when FA and Zr were included in grout mixtures, the fluidity, bleeding and volume change increased with less superplasticizer. The compressive strength of all grout mixtures was quite high at the age of 7 and 28 days, and the ternary mixtures had the excellent development of strength than binary mixtures. Furthermore, autogenous shrinkage properties of ternary grout combining shrinkage reducing agent (SRA) and expansive additive (EA) was evaluated. The 47~80% autogenous shrinkage was reduced by using SRA and EA. In addition, the effectiveness of using SRA and EA was higher for the grout mixture with SF than that with Zr.
철근 배근 방법에 의한 철근콘크리트의 전자파 차폐특성 평가
최진석(Choi, JinSeok),원천봉(Yuan, TianFeng),홍세희(Hong, SeHee),윤영수(Yoon, YoungSoo) 한국방재학회 2020 한국방재학회논문집 Vol.20 No.5
본 연구에서는 콘크리트의 두께와 철근 보강에 따른 철근콘크리트의 전자파 차폐특성에 관한 실험을 수행하였다. 또한, 섬유보강 콘크리트의 강섬유 혼입률 및 철근 간격에 따른 전자파 차폐특성을 평가하였다. 콘크리트는 두께의 증가에 따라 높은 주파수 대역에서 전자파 차폐에 큰 효과를 나타냈으며 철근은 직경의 증가, 철근 간격의 감소 및 보강 층의 증가에 따라 낮은 주파수 대역에서 전자파 차폐에 큰 효과를 나타냈다. 강섬유의 혼입률이 증가할수록 차폐율이 증가하였으며 강섬유를 1.5% 혼입한 변수에서 철근 간격의 감소로 인한 차폐율 증가를 나타냈다. In this study, experimental tests were performed to determine the electromagnetic shielding characteristics of reinforced concrete based on the thickness of concrete and rebar. In addition, the electromagnetic shielding characteristics based on the steel-fiber volume ratio and rebar spacing of fiber-reinforced concrete were evaluated. Concrete showed significant Shielding Effectiveness (SE) in a high-frequency band with increasing thickness, but the rebar exhibited significant SE in the low-frequency band with increasing diameter, decreasing rebar spacing, and increasing layer. The SE increased with the steel fiber volume ratio, and it also increased owing to the decrease in the rebar spacing for 1.5 vol.% steel fibers.
전기로 산화슬래그 혼입 고강도 콘크리트의 미세구조 및 자기센싱 특성 평가
홍세희(Hong, Sehee),원천봉(Yuan, Tianfeng),최진석(Choi, Jinseok),윤영수(Yoon, Youngsoo) 한국방재학회 2019 한국방재학회논문집 Vol.19 No.5
This study analyzes the microstructure and strength properties of high-strength concrete containing electric-arc-furnace oxidizing slag (ES). Thus, three different water-to-binder ratios and four different ES-replacement ratios were considered while evaluating the hydration products of the specimens, their porosity, pore-size distribution, and compressive and splitting tensile strengths, depending on the curing age. According to the x-ray diffraction (XRD) patterns, the ES specimens of both portlandite and hatrurite exhibited higher peak intensities than those of the plain specimen (High-strength concrete, i.e., HSC). Further, from the results of the mercury intrusion porosimetry (MIP) test, it was observed that the cumulative pore volume of the ES specimens was higher than that of the HSC. Also, the porosity of the ES specimen, whose ES-replacement ratio was 20%, was approximately 37.9% higher than that of the HSC. The compressive strength and splitting tensile strength of the ES specimens significantly decreased when the ES-replacement ratio was 20%, while the best self-sensing properties were exhibited. From all the experiments, it was observed that an ES-replacement ratio of 15% exhibited similar microstructure and strength properties to those of the HSC.