• 한국건설순환자원학회논문집
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• 제2권3호
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• pp.180-187
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• 2014

본 연구에서는 시멘트 사용량을 저감하고 다량의 혼화재를 사용하여 고강도 콘크리트 제조 과정에서 시멘트에 의한 $CO_2$ 발생량을 감소시킬 목적으로 혼화재 및 무기계 자극제를 사용한 고강도 콘크리트의 역학적 특성을 평가하였으며, HVMA 결합재 도출과 W/B 변화 및 양생온도에 따른 HVMA 고강도 콘크리트를 실험하였다. 실험결과, 다량의 혼화재와 무기계 자극제인 열병합애시와 무수석고를 혼합 사용한 HVMA 결합재 배합을 설계하였으며, 설계된 HVMA 결합재를 사용할 경우 W/B 26% 수준에서 HVMA 고강도 콘크리트 배합이 유동특성과 역학적 특성이 양호한 것으로 나타났다. 또한 HVMA 결합재를 사용한 고강도 콘크리트의 양생온도 영향을 검토한 결과, 양생온도 $20^{\circ}C$ 이상 확보한 경우에는 50MPa 이상의 고강도 HVMA 고강도 콘크리트 제조가 실용화 가능성이 높은 것으로 나타났다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1999년도 추계학술발표회
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• pp.65-68
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• 1999

A plasma melting system to vitrify ny ash from MSW(Municipal Solid Waste) incinerator has been operated in SHI(Samsung Heavy Industries) since 1996. Waste feeding rate was 200kg/hr. with maximum working power of 500㎾. Because of high melting temperature of fly ash, bottom ash was used as an additive to decrease melting temperature. Data analysis for discharged slag shows volume reduction up to 30% and no leaching of heavy metals such as Pb, Cd, Cr which were an obstacle for landfill and recycle. Atmospheric pollution gas like nitrogen oxides, carbon monoxide, and PCDD/PCDF were restrained below the regulatory limit.

• Advances in concrete construction
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• 제7권4호
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• pp.263-275
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• 2019

In the present work, Granulated Blast Furnace Slag (GBFS) and Fly ash (FA) were used as partial replacement of Natural Sand (NS) and Ordinary Portland Cement (OPC) by weight. One control mix, one with GBFS, three with FA and three with GBFS-FA combined mixes were prepared. Replacements were 50% GBFS with NS and 20%, 30% and 40% FA with OPC. Preliminary investigation on development of compressive strength was carried out at 7, 28 and 90 days to ensure sustainability of waste materials in concrete matrix at room temperature. After 90days, thermo-mechanical study was performed on the specimen for a temperature regime of $200^{\circ}-1000^{\circ}C$ followed by furnace cooling. Weight loss, visual inspection along with colour change, residual compressive strength and microstructure analysis were performed to investigate the effect of replacement of GBFS and FA. Although adding waste mineral by-products enhanced the weight loss, their pozzolanicity and formation history at high temperature played a significant role in retaining higher residual compressive strength even up to $800^{\circ}C$. On detail microstructural study, it has been found that addition of FA and GBFS in concrete mix improved the density of concrete by development of extra calcium silicate gel before fire and restricts the development of micro-cracks at high temperature as well. In general, the authors are in favour of combined replacement mix in view of high volume mineral by-products utilization as fire protection.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.881-884
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• 2006

Wasted phosphogypsum is a by-product from the phosphoric acid process of manufacturing fertilizers. It consists mainly of $CaSO_4{\cdot}2H_2O$ and contains some impurities. The purpose of this study is to utilize wasted phosphogypsum into an admixture for concrete products cured by steam This paper is to investigate the strength properties of cement composites containing high volume phosphogypsum. The cement composites were composed of OPC, phosphogypsum, fly-ash and granulated blast-furnace slag with activators. As a result, the strength of cement composites containing high volume wasted phosphogypsum were shown high level when granulated blast-furnace slag was mixed. Therefore, PG could be used as a steam curing admixture for concrete 2th production with reduction of OPC.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.47-48
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• 2016

Recently over the world, many studies on the methods for using some binding materials which replace cement, such as FA, etc., for reducing CO₂. However, it has sometimes been reported that some cement products without passing through the refining process at some of FA refineries in Korea are released for sales for some reasons of shortening the production time and the cost reduction, etc., so it exerts a bad effect on the quality of many construction structures. Therefore, in this study, it was intended to conduct an experimental review on the effects of using an extreme quality of FA which is distributable domestically on the engineering characteristics of high-strength mortar. As a result, it was judged that it is beneficial for the engineering characteristics of concrete, such as, flow property, air volume and strength, etc, to use some refined FA.

• 한국건설순환자원학회논문집
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• 제5권1호
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• pp.45-52
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• 2017

이 연구에서는 고로슬래그 다량 치환 콘크리트의 원전 콘크리트 적용을 위하여 기존 원전 콘크리트와의 내구성능 비교 및 분석을 수행하였다. 연구결과에 따르면 고로슬래그를 50% 치환한 콘크리트의 압축강도는 초기강도는 기존 원전 콘크리트보다 낮지만, 우수한 장기강도를 나타내었다. 반면, 기존 원전 콘크리트의 초기강도는 높았지만, 장기강도 발현율이 낮게 나타났다. 내구성능의 평가결과, 고로슬래그를 50% 치환한 콘크리트의 내구성능은 모든 평가항목에서 플라이애시 20% 치환 콘크리트와 비교하여 동등이상의 성능을 나타내었다. 특히. 저강도에서의 고로슬래그 50% 치환한 콘크리트는 염해 저항성과 탄산화 저항성, 동결융해 저항성의 향상효과가 뚜렷하게 나타났다. 반면, 감마선 조사에 따른 콘크리트 압축강도와 화학성분의 변화는 미미하게 나타났다.

• Computers and Concrete
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• 제30권6호
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• pp.393-407
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• 2022

Due to the enormous cement content, pozzolanic materials, and the use of different aggregates, sustainable controlled low-strength material (CLSM) has a higher material cost than conventional concrete and sustainable construction issues. However, by selecting appropriate materials and formulations, as well as cement and aggregate content, whitethorn costs can be reduced while having a positive environmental impact. This research explores the desire to optimize plastic properties and 28-day unconfined compressive strength (UCS) of CLSM containing powder content from unprocessed-fly ash (u-FA) and recycled fine aggregate (RFA). The mixtures' input parameters consist of water-to-cementitious material ratio (W/CM), fly ash-to-cementitious materials (FA/CM), and paste volume percentage (PV%), while flowability, bleeding, segregation index, and 28-day UCS were the desired responses. The central composite design (CCD) notion was used to produce twenty CLSM mixes and was experimentally validated using MATLAB by an Artificial Neural Network (ANN). Variance analysis (ANOVA) was used for the determination of statistical models. Results revealed that the plastic properties of CLSM improve with the FA/CM rise when the strength declines for 28 days-with an increase in FA/CM, the diameter of the flowability and bleeding decreased. Meanwhile, the u-FA's rise strengthens the CLSM's segregation resistance and raises its strength over 28 days. Using calcareous powder as a substitute for cement has a detrimental effect on bleeding, and 28-day UCS increases segregation resistance. The response surface method (RSM) can establish high correlations between responses and the constituent materials of sustainable CLSM, and the optimal values of variables can be measured to achieve the desired response properties.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.271-273
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• 2012

This paper is to investigate the effect of waste cooking oil(WCO) on carbonation resistance of high volume fly ash and blast furnace slag concrete. WCO and paint were applied for carbonation resistance materials. As expected, the application of WCO to the concrete help it reduce carbonation depth remarkably, regardless of mixture types. This may be due to the fact that WCO makes the capillary pore block by activating saponification. It is found that the degree of carbonation reduce due to WCO is much higher than the case by Paint.

• 한국건설순환자원학회논문집
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• 제4권4호
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• pp.117-124
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• 2009

본 연구에서는 FA 다량 치환 콘크리트의 품질 개선 및 기타 품질 향상을 목적으로 선행 연구에서 개발된 조강형 혼화제(GA)로 FA 다량 치환 콘크리트의 품질 향상 가능성을 평가하였다. 실험은 우선 FA 15%를 치환한 배합에 나프탈렌계 혼화제(이하 NA)를 사용한 것을 Plain으로 하였고, FA 20, 25% 및 30%를 치환한 경우, GA를 사용하여 콘크리트의 제반특성을 Plain과 비교 실험 하였다. 굳지 않은 콘크리트 특성으로 유동성은 GA를 사용할 경우 저하하므로 그 사용량을 증가시켜주어야 하는데, 단 W/B 60%의 경우는 Plain 보다 슬럼프 로스가 약 35~70 mm 감소하여 유리한 것으로 나타났다. 공기량은 FA 사용량 증가에 따라 FA에 포함된 미연소탄분의 AE제 흡착작용에 기인하여 감소함으로서 AE제 사용을 비례적으로 증가시켜 주어야함을 알 수 있었다. 블리딩은 FA 20%에서 블리딩 발생량이 가장 적게 나타나 블리딩 저감 효과를 기대할 수 있었다. 경화 콘크리트의 특성으로 응결시간은 GA를 사용한 경우 Plain과 동등한 수준으로 나타나, 응결 지연현상을 줄일 수 있는 것으로 판단된다. 압축강도는 W/B 및 양생온도와 관계없이 GA를 사용한 경우 Plain과 동등한 강도 발현을 확인 할 수 있었으나, FA 30% 치환한 경우는 사용상에 주의가 필요할 것으로 사료된다. 동결융해 저항성은 Plain보다 초기 값이 작게 나타났으나, 전반적으로 큰 차이가 아니기 때문에 내동해성 문제가 없을 것으로 판단된다. 촉진 중성화는 GA를 사용함에 따라, FA를 다량 사용할 경우 단점으로 지적되는 중성화 취약에 대한 문제는 어느 정도 해결 할 수 있을 것으로 분석되었다.

• International Journal of Concrete Structures and Materials
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• 제7권2호
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• pp.95-110
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• 2013

We report various synchrotron radiation laboratory based techniques used to characterize cement based materials in nanometer scale. High resolution X-ray transmission imaging combined with a rotational axis allows for rendering of samples in three dimensions revealing volumetric details. Scanning transmission X-ray microscope combines high spatial resolution imaging with high spectral resolution of the incident beam to reveal X-ray absorption near edge structure variations in the material nanostructure. Microdiffraction scans the surface of a sample to map its high order reflection or crystallographic variations with a micron-sized incident beam. High pressure X-ray diffraction measures compressibility of pure phase materials. Unique results of studies using the above tools are discussed-a study of pores, connectivity, and morphology of a 2,000 year old concrete using nanotomography; detection of localized and varying silicate chain depolymerization in Al-substituted tobermorite, and quantification of monosulfate distribution in tricalcium aluminate hydration using scanning transmission X-ray microscopy; detection and mapping of hydration products in high volume fly ash paste using microdiffraction; and determination of mechanical properties of various AFm phases using high pressure X-ray diffraction.