• 콘크리트학회논문집
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• 제11권5호
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• pp.99-105
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• 1999

In producing high strength concrete, the most practical method is to use high range water reducing admixture(HRWR). Workabili쇼 of concrete using HRWR varies rapidly with elapsed time after mixing. Effects of fly ash and gypsum on slump loss and compressive strength of concrete were examined by experiment in this study. The slump loss of high strength concrete was reduced with increase of substitution ratio of fly ash. When 2~4% gypsum of cement weight was applied, the reduction of slump loss was not prominent and strength increase appeared at all test ages.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.89-92
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• 2006

To investigate the properties of high flowing and high strength concrete with crushed sand and fly ash for CFT structure, many batches were performed by a trial-error method. In the experiment W/B was set up three levels as 0.25, 0.30 and 0.35. Also the variables of the experiment were a substitution ratio of fly ash, a blend ratio of crushed sand and the ages of specimens(3, 7, 28 days). The results of this study are summarized as the follows; 1) The effect a substitution ratio of fly ash on the compressive strength was not consistent with age. For twenty-eight day compressive strength, the best result was come out when cement was substituted by 10% of fly ash. 2) The decrease of the water binder ratio, the increase of compressive strength and elastic modulus. Also the relationship is very similar to the case of a normal concrete

• Computers and Concrete
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• 제6권1호
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• pp.19-40
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• 2009

This paper describes the development of modified heat of hydration and maturity-strength models for concrete containing fly ash and slag. The modified models are developed based on laboratory and literature test results, which include different types of cement, fly ash, and slag. The new models consider cement type, water-to-cementitious material ratio (w/cm), mineral admixture, air content, and curing conditions. The results show that the modified models well predict heat evolution and compressive strength development of concrete made with different cementitious materials. Using the newly developed models, the sensitivity analysis was also performed to study the effect of each parameter on the hydration and strength development. The results illustrate that comparing with other parameters studied, w/cm, air content, fly ash, and slag replacement level have more significantly influence on concrete strength at both early and later age.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.201-202
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• 2016

Energetically-modified material using reject fly ash was manufactured to investigate the effect of the material on strength characteristic of cement mortar. In order to modify reject fly ash, a vibration mill was used. after grinding process, the defects in the alignment of atom was checked using transmission electron microscope. It was found that the compressive strength values of 28 days-cured specimens using energetically-modified reject fly ash (ERFA) were higher than that of mortar with non-ground reject fly ash.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.241-244
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• 1999

This study is represented the strength and freeing-thawing properties of recycled aggregate concrete mixed fly ash by experiment. The experimental variables are the substitution ratio of recycled aggregate and the mixing ratio of fly-ash. For each specimens, there were tested compressive strength and freeze-thaw resistance. It is able to find from the experimental result that the recycled aggregate concrete has good properties as general concrete on the compressive strength and the durability.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.199-200
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• 2019

The purpose of the research is assessing the possibility of strength recovery for mortar added with accidently high amount of fly ash. For compressive strength at 28 day, the sample painted with sodium hydroxide showed higher compressive strength than the sample painted with calcium hydroxide. Regarding the curing conditions, the curing temperature 65℃ provided better conditions than the curing temperature 20℃ in aspect of solution penetration depth and reactivity of fly ash. In the case of drying after saturation, the case painted with sodium hydroxid 65℃ showed the clearest engrossing mark.

• 대한환경공학회지
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• 제28권6호
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• pp.661-666
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• 2006

칼슘함량이 낮은 F급 플라이 애쉬와 알칼리 활성화 용액으로 구성된 페이스트의 압축강도 특성에 대한 연구를 수행하였다. 수산화나트륨과 물유리 그리고 물을 혼합하여 제조한 이들 활성화 용액은 매우 높은 $OH^-$ 농도를 가지고 있다. 알칼리 활성화 용액의 조성과 온도는 플라이 애쉬-시멘트 페이스트의 압축강도 발현에 대한 현저한 영향 인자임을 보여주었다. 50 MPa 이상의 압축강도는 플라이 애쉬를 각각 $60^{\circ}C$에서 48시간과 $85^{\circ}C$에서 24시간 양생하여 얻었다. 본 연구결과, F급 플라이 애쉬/NaOH/물유리의 무게 비율 25:8:2와 활성화 용액/플라이 애쉬의 무게 비율 0.6/1.0은 높은 강도를 가진 페이스트를 위한 적정 혼합비율로 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.333-338
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• 2000

The purpose of this study is to evaluate the compressive strength properties of municipal waste ash hardening using the unrefined fly-ash and paper sludge ash and to offer basic data to someone for recycling municipal waste ash. Unrefined fly-ash and paper sludge ash are used with admixture. MWA are tested that grading, specific gravity and pH value and observed microsructure of particle with SEM. The compressive strengths of MWA hardening which is mixed with regular ratio according to each admixture are measured. In the results of test, fly-ash is very effective for reducing content of cement by 50% in the recycling of MWA. But proper content mixed paper sludge ash is recommend by about 20% in binder.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.565-568
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• 2008

플라이애쉬는 상대적으로 낮은 초기 강도 발현율에 의해서 고로슬래그 미분말에 비하여 사용이제한적이다. 따라서 플라이애쉬는 우수한 경제성과 많은 발생량에도 불구하고 많은 양이 활용되지 못하고 매립되고 있다.본 연구에서는 자극제가 플라이애쉬를 사용한 콘크리트의 성능에 미치는 영향을 확인하고 플라이애쉬의 활용 증대 가능성을 검토하였다. 연구 결과 자극제를 사용한 플라이애쉬 콘크리트가 동일 슬럼프, 공기량 및 로스를 가지면서 일반적인 혼화제를 사용한 콘크리트보다 압축강도가 높게 나타났으며 다양한 요인에서의 자극제의 성능 발현을 검증할 경우 자극제를 사용한 플라이애쉬 콘크리트의 현장 적용 확대가 가능할 것으로 사료된다.

• 한국재료학회지
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• 제27권2호
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• pp.76-81
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• 2017

Recently, there have been many efforts to establish suitable processes for recycling fly ash, which is produced in thermal power plants and which poses serious environmental problems. Use of fly ash as a major ingredient of ceramic tiles can increase fly ash utilization, as well as reduce the cost of raw materials in ceramic tile production. In this study, the effects of fly ash addition on ceramic tile properties such as bending strength, water absorption and porosity were investigated. A manufacturing process of ceramic tile was developed for utilization of fly ash with high carbon content. In this approach, it is important to hold the ceramic tiles at a temperature that is sufficient for carbon oxidation, before the pores supplying oxygen to the inside of the ceramic tile are sealed. Ceramic wall tiles were manufactured with 0-40wt% of fly ash addition. The water absorption and porosity of the fired body were slightly changed with increasing fly ash content up to 30wt% and decreased with greater amounts of fly ash addition. The bending strength of ceramic tile including 10wt% fly ash increased, reaching a level comparable to that of ceramic tile without fly ash.