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페로니켈슬래그 잔골재의 바닥용 건조모르타르 적용성 평가
조봉석,김원기,황인성,구경모 한국건축시공학회 2019 한국건축시공학회지 Vol.19 No.2
Fine aggregate made of ferronickel slag(FNS) is similar to natural fine aggregates and is used in concretestructures both domestically and abroad, but its applications and research areas are limited. In this research, in orderto expand the availability of FNS and improve the performance of cement mortar products, the applicability of FNS ondry mortar for floor was examined. Experimental results show that FNS improves flow of cement mortar because ithas low absorption rate, spherical shape, and glassy surface. Also, the high stiffness of the FNS aggregate itself isconsidered to contribute to the improvement of cement mortar quality such as crack reduction by improving thecompressive strength and shrinkage reducing. In addition, when FNS fine aggregate is applied, it was possible tosecure the impact sound insulation performance equal to or higher than that of mortar using natural fine aggregate. 페로니켈슬래그 잔골재는 천연 잔골재와 유사한 특성이있어 국내·외적으로 콘크리트 구조물에 사용되고 있으나그 용도와 연구의 영역이 한정적이다. 이에 본 연구에서는FNS의 활용성 확대와 모르타르제품의 성능개선을 목적으로 바닥용 건조모르타르에 대한 FNS의 적용성을 검토하고자 하였다. 실험 결과, FNS는 흡수율이 낮고 구형의 입형이며 표면이 유리질 피막의 특성이 있어 모르타르의 플로을 향상시켰다. 또한 골재 자체의 높은 강성은 몰탈 압축강도의 향상 및 수축저감 효과를 나타내어 균열저감 등의품질향상에 기여할 것으로 판단된다. 뿐만 아니라 천연 잔골재를 사용한 모르타르와 비교하여 FNS를 적용하는 경우동등수준 이상의 충격음 차단성능을 확보할 수 있었다.
Properties of cementless binders using desulfurization slag as an alkali activator
조봉석,최영철 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.1
The alkali stimulus provided by the Ca(OH)2 contained in desulfurization slag (DS), a byproduct generated in the preliminarytreatment of molten iron and composed of Ca(OH)2, CaCO3, and 2CaO·SiO2, is used to cause a cement-free binder to hardenby serving as an alkali activator for ground, granulated blast-furnace slag (BFS). The 28-day compressive strength of the BFSDSbinder was found to be about 30% that of ordinary Portland cement (OPC), but the 28-day strength of a binder madefrom BFS, DS, and anhydrous gypsum (G) was found to be similar to that of OPC. It is confirmed that BFS-DS-G bindershave very low hydration heat, which is of use in reducing the heat generated during the curing of mass concrete. The mainhydration product of the BFS-DS-G binder is found to be ettringite. Scanning electron microscope images reveal that theneedle-shaped ettringite formed in the BFS-DS-G binder is much thicker than that formed in OPC. This thick, needle-shapedettringite forms a skeletal structure, providing structural stability, and fills the gaps between hydration products such ascalcium silicate hydrates and calcium aluminum hydrates, making it highly effective in forming a dense structure. Thewidespread use of BFS-DS-G binders would result in the value-added utilization of byproducts from the iron & steel makingprocess, and provide an environmentally friendly and more economical construction material, and contribute to a reductionin CO2 emissions generated by the cement industry.
뿜칠시공에 의한 단면복구재의 시공성 및 공학적 특성에 관한 실험적 연구
조봉석,김영선,장재봉,김용로,김경덕,김무한 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1
These days, serious concerns of reinforced concrete have been raised recently over steel-bar corrosion, cracking, the deterioration of durability and structural stress resistance and so on, all due to the effects of exterior factors. Such being the case, in domestic, various repair materials and method systems to keep up with these reinforced concrete deteriorated due to salt damage, carbonation, chemical decay et. developed and applied. However, on-site quality control of various repair materials and method systems isn't achieved desirably because it is depend completely on a men of experience' opinions above all else regardless of various on - site environments. In this background, mock up test with due regard to real on-site environments was performed to secure fundamental data for establishment of desirable on-site quality control. Mock up test using repair mortar analyzed from angles of construction methods, mechanical spraying pressures, W 1M. Construction methods were designed manpower method and spraying method, spraying pressures were designed 32, 42, 52 psi, W/M were designed 14.4, 15.4, 16.4 %. And compressive strength, Chloride ion diffusion coefficient, bond strength, SEM of mock up test specimens were evaluated. In conclusion, we confirmed excellency of mechanical spraying pressures, fined extremely excellency of condition of spraying pressure 42 ps, W/M 14.4% within this study. therefore the results of this study will be useful to provide fundamental data for establishment of desirable on-site quality control.
스테인리스 전기로 산화슬래그의 콘크리트용 잔골재 활용방안 검토
조봉석 한국구조물진단유지관리공학회 2014 한국구조물진단유지관리공학회 논문집 Vol.18 No.3
최근 골재 수급불균형 문제 및 천연자원 고갈에 관한 사회적 관심이 집중되는 가운데, 종래 철강공정에서 부산물로 발생하는 슬래그 중 전기로 산화슬래그는 그 물리적 특성이 일반 골재와 유사한 특성이 있어 콘크리트용 골재로서 활용가능성이 높게 평가되나 슬래그 중 함유되어 있는 free-CaO에 의한 표면결함을 야기하는 문제를 내재하고 있다. 본 연구는 이러한 전기로 산화슬래그 골재의 화학적 안정성 확보 방안을 도출하고 이를 통해 안정화된 슬래그 골재를 용도별 콘크리트용 잔골재로 활용하여 콘크리트의 역학적 성능 및 내구성능을 실험적으로 평가함으로서 최종적으로 전기로 산화슬래그 잔골재의 활용방안을 제시하는 데 그 목적이 있다. 본 연구결과, 전기로 산화슬래그의 골재입경 조정, 소정 기간 동안의 자연 에이징 처리에 의해 팝아웃 등의 표면결함을 대폭 저감할 수 있는 것으로 나타났으며, 콘크리트 용도별 대체율에 따른 역학적 성능 및 내구성능은 일반 골재와 비교하여 동등 또는 동등 이상의 성능을 발현하는 것으로 평가되었다. 향후 전기로 산화슬래그 잔골재 활용시에는 콘크리트의 미관저해 현상이 나타나지 않도록 충분한 사전 에이징 또는, 가공처리 등 안정성 확보를 위한 품질관리가 선행되어야 할 것이다. 또한, 철강부산물의 친환경적인 자원순환 시스템을 확립하기 위해서는 전기로 산화슬래그 골재에 대한 품질관리방안 확립과 더불어 다양한 용도개발이 이루어져야 하며 각종 공학적 특성 및 내구성에 관한 지속적인 연구개발이 이루어져야 할 것이다. Recently, more focus is shift to imbalances in aggregate market supply and demand and an exhaustion of natural resources. In this situation, Electric arc furnace oxidizing slag (EAF Slag) has high application possibility as aggregate for concrete due to similar property with general aggregate. In this study, We've got the plan to assure the chemical stability of EAF Slag, and then experimentally tested the mechanical performance and durability for the fine aggregate used EAF Slag. On this test result, we suggest the application plan. At the result of this study, it shows that EAF slag would reduce the surface defect such as pop-out due to natural aging for the fixed hour and adjustment the grain size of EAF Slag. And mechanical performance and durability according to the replacement rate of concrete service, were revealed more than equal or equal compare to general aggregate. Hereafter, quality control must precede not to impede the beauty of concrete surface as assure the safety for aging and processing. And, to establish the environmental resource recycling system for by-products of steel, it should be made development of various application and guideline of quality control for the EAF slag aggregate. Moreover, it must be constantly studied all kind of engineering performance and durability for related to this study.