• 한국세라믹학회지
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• 제53권3호
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• pp.354-361
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• 2016

The purpose of this study was to prepare lightweight foamed concrete by mixing coal fly ash of circulating fluidized bed combustion(CFBC) with cement, and to develop uses for recycling by analyzing carbonation behavior resulting from a change in conditions for pressurized carbonation. For concrete, CFBC coal fly ash was mixed with Portland cement to the water-binder ratio of 0.5, and aging was applied at room temperature after 3 days of curing at $20^{\circ}C$, RH 60%. For carbonation, temperature was fixed at $60^{\circ}C$ and time at 1 h in the use of autoclave. Pressures were controlled to be $5kgf/cm^2$ and the supercritical condition of $80kgf/cm^2$, and gas compositions were employed as $CO_2$ 100% and $CO_2$ 15%+N2 85%. In the characteristics of produced lightweight concrete, the characteristics of lightweight foamed concrete resulting from carbonation reaction were affirmed through rate of weight change, carbonation depth test, air permeability, and processing analysis for the day 28 specimen. Based on these results, it is concluded that the present approach could provide a viable method for mass production of eco-friendly lightweight foamed concrete from CFBC coal fly ash stabilized by carbonation.

• 콘크리트학회논문집
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• 제22권4호
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• pp.567-574
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• 2010

지금까지 환경 친화적 재료로서 황토에 관한 연구는 포틀랜드 시멘트를 부분적 대체하거나, 완전 대체하는 연구로 진행되어 왔다. 기존의 대부분의 연구에서는 압축강도, 건조수축, 크리프 등 황토 콘크리트의 역학적 성질에 초점이 맞춰졌다. 이 연구에서는 황토 콘크리트로 제작된 보 실험체의 휨 성능을 실험하였다. 이번 실험에서는 시멘트를 20% 대체하는 활성 황토를 사용한 콘크리트와 시멘트를 100% 대체하는 활성 황토 콘크리트가 사용되었다. 단순보 실험은 2점 정적 재하 하중으로 실험하였다. 휨 강도, 균열 모멘트, 처짐, 연성도 등의 결과를 일반 포틀랜드 시멘트 콘크리트로 제작된 보의 실험 결과와 비교하였다.

• Computers and Concrete
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• 제20권4호
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• pp.461-468
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• 2017

With the increasing demand in the production of concrete, there is a need for adopting a feasible, economical and sustainable technique to fulfill practical requirements. Self-Compacting Concrete (SCC) is one such technique which addresses the concrete industry in providing eco-friendly and cost effective concrete. The objective of the present study is to develop a mix design for SCC with Crushed Rock Fines (CRF) as fine aggregate based on the plastic viscosity of the mix and validate the same for its fresh and hardened properties. Effect of plastic viscosity on the fresh and hardened properties of SCC is also addressed in the present study. SCC mixes are made with binary and ternary blends of Fly Ash (FA) and Ground Granulated Blast Slag (GGBS) with varying percentages as a partial replacement to Ordinary Portland Cement (OPC). The proposed mix design is validated successfully with the experimental investigations. The results obtained, indicated that the fresh properties are best achieved for SCC mix with ternary blend followed by binary blend with GGBS, Fly Ash and mix with pure OPC. It is also observed that the replacement of sand with 100% CRF resulted in a workable and cohesive mix.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.33-34
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• 2023

Corrosion of reinforcement steel is a major cause of deterioration in reinforced concrete (RC) structures. In order to protect these structures from corrosion, corrosion inhibitors are added to the concrete mix. In recent years, zwitterionic compounds have shown promising results as corrosion inhibitors in concrete due to their ability to form a protective layer on the surface of the reinforcement steel. The experimental study involves preparing concrete samples with different concentrations of adding the hybrid corrosion inhibitor at a high concentration of chloride ions. This study aims to determine the chloride threshold value and service life of hybrid corrosion inhibitors in reinforced concrete based on zwitterions. The samples are subjected to accelerated corrosion tests in a chloride environment to determine the threshold value and service life of the corrosion inhibitor. The effect of hybrid inhibitor on mechanical properties is guaranteed in allowable range. The chloride threshold concentration and service life of hybrid inhibitor containing samples perform greater than those of plain RC.

• 한국산학기술학회논문지
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• 제21권2호
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• pp.601-610
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• 2020

최근, 세계적인 기후변화로 인하여 여름철마다 가뭄으로 인한 피해는 점점 심각해지는 상태이다. 이러한 문제를 해결하기 위하여, 산간오지에는 고정(콘크리트)보가 아닌 수위조절이 가능한 가동보가 설치되고 있다. 기존의 가동보 구동방식은 시설관리 및 인력소모로 인해 고가의 운용비용이 발생하여 운용상 어려움을 겪고 있다. 또한, 가동보는 대부분 전력계통과 연계하여 사용하고 있으므로 오지에 설치되는 경우, 전력계통 연계비용에 대한 부담이 증가하고 운용비용도 상승하는 문제점이 발생되고 있다. 따라서, 본 논문에서는 상기의 문제점들을 해결하기 위하여, 가동보(공압식)에 공급되는 기존의 전원을 태양광모듈과 리튬이온전지를 이용한 자연에너지 전원공급시스템으로 대체하는 최적 운용알고리즘과 리튬이온전지의 SOC(state of charge) 평가 알고리즘을 제시한다. 또한, 전력계통의 상용해석 프로그램인 PSCAD/EMTDC를 이용하여 50kW 전원공급시스템의 모델링을 수행하여, 독립운전모드와 계통연계운전모드에서 안정적으로 운용되고 있음을 확인하고, 투자비용에 대한 편익을 분석하여 상용화 가능성을 제시한다.

• 한국도로학회논문집
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• 제15권2호
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• pp.113-119
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• 2013

PURPOSES : The objectives of this study are to develop the eco-friendly pavement material using polyurethane binder and evaluate mechanical properties of the developed binder and concrete. METHODS : The bending beam test was conducted to select the sample candidates of polyurethane binder based on the bending strength. The characteristics of viscosity, curing time, and temperature change of sample binder was examined on different temperature conditions. The mechanical properties of polyurethane binder was estimated using the dynamic modulus testing. The indirect tensile strength test was conducted on polyurethane binder concrete with different gradation and binder content for evaluating the mechanical properties of concretes. RESULTS : Based on the beading beam test, four different binder samples were prepared for estimate the mechanical properties. The viscosity of polyurethane binder tends to increase with increase of liquid temperature and the hardening phenomenon begins 10 to 15 minutes at room temperature after mixing the resin and hardener. It is observed that the dynamic modulus of binder increases as loading frequency increases and change of modulus is found to be the highest in the PU-2I binder type. The PU-2I binder concretes shows the largest value of indirect tensile strength and indirect tensile energy. CONCLUSIONS : The use of polyurethane binder as pavement materials is capable of increasing the pavement performance and reducing the detrimental environmental effect during the highway construction.

• 한국구조물진단유지관리공학회 논문집
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• 제14권1호
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• pp.102-108
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• 2010

본 연구의 목적은 폐 PET병을 재활용하여 만든 섬유(RPET)를 콘크리트 부재에 적용시키기 위한 성능 평가에 있다. RPET 섬유보강 효과를 평가하기 위해서 압축강도, 탄성계수, 쪼갬인장강도와 같은 기초물성실험과 건조수축균열실험을 수행하였다. 기초물성실험에서 RPET의 혼입률이 증가할수록 RPET 보강 콘크리트의 압축강도와 탄성계수는 감소하였고, 쪼갬인장강도는 증가하였다. 건조수축 실험에서 자유건조수축은 증가하였다. 반면에 구속건조수축의 경우 RPET 섬유에 의한 인장 저항성의 증가로 인해 균열 발생을 지연시켰다. RPET 섬유와 PP 섬유를 혼입한 콘크리트 시편의 특성을 비교해보면 두 섬유가 유사하다는 것을 알 수 있다. 따라서 RPET 섬유는 PP 섬유의 대체 재료로서 충분할 뿐만 아니라 폐 PET병을 재활용하고 환경오염을 저감시킨다는 측면에서 친환경적으로 더 뛰어나다는 것을 알 수 있다.

• Structural Engineering and Mechanics
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• 제74권5호
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• pp.671-678
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• 2020

In this work, the dynamic properties of a high performance concrete containing glass powder (GP) was studied. The GP is a new cementitious material obtained by recycling waste glass presenting pozzolanic activity. This eco-friendly material was incorporated in concrete mixes by replacing 20 and 30% of cement. The mechanical properties of building materials highly affect the response of the structure under dynamic actions. First, the resonant vibration frequencies were measured on concrete plate with free boundary conditions after 14, 28 and 90 curing days by using an alternative vibration monitoring technique. This technique measures the average frequencies of several excitations done at different points of the plate. This approach takes into account the heterogeneity of a material like concrete. So, the results should be more precise and reliable. For measuring the bending and torsion resonant frequencies, as well as the damping ratio. The dynamic properties of material such as dynamic elastic modulus and dynamic shear modulus were determined by modelling the plate on the finite element software ANSYS. Also, the instantaneous aroused frequency method and ultrasound method were used to determine the dynamic elastic modulus for comparison purpose, with the results obtained from vibration monitoring technique.

• Structural Engineering and Mechanics
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• 제65권2호
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• pp.203-211
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• 2018

This paper introduces the development process of NCC(New Concrete Cutting) system and analyzes first verification test. Based on the first verification test results, some problems of NCC system have been newly modified. We carry out the second verification test. We tried to verify cutting performance and dust control efficiency of NCC system through the cutting test of concrete bridge piers. In particular, this verification test strives to solve the problem of concrete dust, which is the biggest problem of dry cutting method. The remaining dust problems in cutting section tried to solve through this verification test. This verification test of the NCC system shows that the dust problem of dry cutting method is closely controlled and solved. In conclusion, the proposed NCC method is superior to the dry cutting method in all aspects, including cutting performance, dust vacuum efficiency and cooling effect. The proposed NCC system is believed to be able to provide eco-friendly cutting technology to various industries, such as the removal of the SOC structures and the dismantling of nuclear plants, which have recently become a hot issue in the field of concrete cutting.

• Advances in concrete construction
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• 제13권3호
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• pp.233-242
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• 2022

An attempt is made to develop an eco-friendly concrete with ground granulated blast furnace slag (GGBS) and pond ash as partial replacement materials for cement and fine aggregate, respectively without compromising the strength and durability. Sixteen concrete mixes were developed by replacing cement and fine aggregate by GGBS and pond ash, respectively in stages of 10%. The maximum replacement levels of cement and fine aggregates were 50% and 30% respectively. Experimental results revealed that the optimum percentage of GGBS and pond ash replacement levels were 30% and 20% respectively. The optimized mix was used further to study the flexural behavior and durability properties. Reinforced Concrete (RC) beams were cast and tested under a four-point bending configuration. Also, the specimens prepared from the optimized mix were subjected to alternate wet and dry cycles of acid (3.5% HCl and H₂SO₄) and sulphate (10% MgSO₄) solutions. Results show that the optimized concrete mix with GGBS and pond ash had a negligible weight loss and strength reduction.