• 제목, 요약, 키워드: fly ash

검색결과 1,941건 처리시간 0.047초

플라이애시의 활성도지수 평가에 관한 기초적 연구 (Fundamental Study on Evaluation method of Activity Factor of Fly Ash)

  • 박상준
    • 한국건축시공학회지
    • /
    • v.8 no.5
    • /
    • pp.59-65
    • /
    • 2008
  • In the evaluation method of KS on the activity factor of fly ash, same amount of cement should be replaced with fly ash. Therefore, contradictory effects on concrete strength exist, i. e. strength decease due to low content of cement and strength increase of strength due to filling-pore-function of fly ash. European Committee for Standardization (CEN) specifies the method 1 to 4. adding fly ash without reducing the content of cement, for the evaluation method on activity factor of fly ash. This study investigates the applicability of the method 2 of CEN to mix design of concrete. The followings are derived ; There is a key ratio of f)y ash mixing which enhances the incremental ratio of mixing water to improve fluidity of mortar. The incremental ratio of mixing water is maximized about 11% ratio of fly ash mixing. Compressive strength most slightly increases at that ratio of fly ash mixing. Activity factor of fly ash increases as water-cement ratio becomes low and contents of fly ash becomes high. Moreover, quality of fly ash and condition of mix design affect the applicable amount of fly ash and available range of water-cement ratio. However, this method has some problems for practical purpose because activity factors of fly ash for some cases are over 1.0. Further research should be conducted to develop more useful method of evaluating activity factor of fly ash.

Fly Ash가 토양(土壤)의 물화학성(物化學性)에 미치는 영향(影響) (Effect of fly ash on the physico-chemical properties)

  • 박만;허남호;최정
    • 한국환경농학회지
    • /
    • v.10 no.2
    • /
    • pp.133-137
    • /
    • 1991
  • Fly ash가 토양(土壤)의 화학성(化學性) 및 물리성(物理性)에 미치는 영향(影響)을 규명(糾明)하기 위하여 Fly ash를 증류수(蒸溜水) 및 0.5N-acetic acia로 추출하여 각종 무기성분(無機成分)의 용출량(溶出量)을 측정(測定)하고 Fly ash를 토양(土壤)에 처리(處理)한 경우 토양물리성(土壤物理性)의 변화(變化)를 조사(調査)하였다. Fly ash의 주요결정광물(主要結晶鑛物)은 mullite와 석영(石英)이었다. 증류수(蒸溜水)보다 Acetic acid로 Fly ash를 추출(抽出)할 경우 훨씬 많은 양(量)의 무기성분(無機成分)이 용출(溶出)되었다. 이때 Si 및 Al는 증류수(蒸溜水)에 의(依)해서 거의 용출(溶出)되지 않았다. 토양(土壤)의 투수성(透水性) 및 포장용수량(圃場容水量)은 Fly ash를 토양(土壤)에 10% 이하(以下) 첨가(添加)하면 향상(向上)되었으나 그 이상(以上) 처리시(處理時)에는 저하(低下)되었다. 토양(土壤)의 신축성(伸縮性) 및 경도(硬度)는 Fly ash를 10% 이하(以下)로 처리(處理)할 경우 큰 영향(影響)을 받지 않았다.

  • PDF

Sequential Extraction을 이용한 Fly ash의 Cd 흡착 양상 평가

  • 이광헌;이승학;이아라;명동일;박준범;김형석
    • 한국지하수토양환경학회:학술대회논문집
    • /
    • /
    • pp.376-379
    • /
    • 2004
  • pH has been regarded as a master variable governing the heavy metal sorption on fly ash. However, the chemical constituents in the fly ash could also suggest a potential sorption site for heavy metals. So, in this study sequential extraction method is employed to evaluate the sorption behavior of fly ash for cadmium. Two different fly ashes (S-fly ash, T-fly ash) were obtained from different power plants in Korea. First, cadmium is adsorbed under four different initial pHs. And, Cd sorbed in fly ash was sequentially desorbed following the sequential extraction method suggested by Tessier. In test results, the effect of pH increase was differently exerted in two fly ash. In S-fly ash, exchangeable fraction was dominated in low initial pH, however, as increasing initial pH, the fraction bound to carbonate increased. In the T-fly ash, regardless of initial pH the fraction bound to carbonate was major part of sorption estimated. The fraction bound to Fe/Mn oxide was about 10% in T-fly ash, and 5% in S-fly ash at high pH.

  • PDF

점토-플라이 애시 혼합물의 지반공학적 특성 (Geotechnical Properties of Clay-Fly Ash Mixtures)

  • 권무남;정성욱;이상호;구정민;김현기
    • 한국농공학회논문집
    • /
    • v.46 no.5
    • /
    • pp.99-106
    • /
    • 2004
  • Although fly ash has possesses viable engineering properties, an overwhelming majority of fly ash from coal combustion is still placed in storage or disposal sites. This study was undertaken to investigate the physical and mechanical properties of clay-fly ash mixture and to furnish engineering data when fly ash utilized as engineering materials. This paper includes geotechnical properties of fly ash, clay-fly ash mixtures and results of compaction test, unconfined strength test, direct shear test, leaching test and stability analysis of clay-fly ash bank slope. If proper amount of fly ash was put in clay, the clay-fly ash mixture has an increase of unconfined strength and stability of bank slope.

점토-Fly Ash 혼합물로 된 제체의 사면안정 해석(지반공학) (The Analysis of Slope Stability on Clay-Fly Ash Mixtures Embankment)

  • 권무남;정성욱;김현기
    • 한국농공학회:학술대회논문집
    • /
    • /
    • pp.477-483
    • /
    • 2000
  • Fly ash is the unburned residue resulting from the combustion of coal in utility and industrial boilers such as thermal power plants. Annually about 5 million tons of fly ash is being produced in korea. Less than 25 percent of total volume of fly ash is currently being used effectively for some ways. In the future, the volume of fly ash discharge from thermal power stations will be increasing more and more, and the development of the utilization of high volume fly ash is required. Fly ash has a lower compacted density and specific gravity than coarse grained natural aggregates but equivalent strength properties indicating that the fly ash could be used as a structural fill materials. So, clay-fly ash mixtures can be used as a fill material in the construction of embankments. Laboratory tests have been carried out to determine the physical, chemical, and geotechnical characteristics of the clay and fly ash. The fly ash is mixed with the clay in different proportions and the geotechnical characteristics of the mixtures have been studied also. In this study describes the results of the experimental study. The implications of the use of clay and clay-fly ash mixtures on the stability of embankments are discussed.

  • PDF

Experimental and SEM Analyses of Ground Fly Ash in Concrete

  • Brueggen, Beth;Kang, Thomas H.K.;Ramseyer, Chris
    • International Journal of Concrete Structures and Materials
    • /
    • v.4 no.1
    • /
    • pp.51-54
    • /
    • 2010
  • Fly ash is used in concrete to improve the fresh and hardened properties of concrete, including workability, initial hydration temperature, ultimate strength and durability. A primary limitation on the use of large quantities of fly ash in blended cement concrete is its slow rate of strength gain. Prior studies investigated the effects of grinding fly ash and fly ash fineness on the performance of concrete containing fly ash. This study aims to discover the sources of those effects, to verify the compressive strength behavior of concrete made with raw and processed Class C fly ash, and to investigate the properties of fly ash particles at the microscopic level. Concrete cylinder test results indicate that grinding fly ash can significantly benefit the early age strength as well as the ultimate strength of concrete with ground fly ash. Therefore, it is demonstrated that grinding fly ash increases its reactivity. Scanning Electron Microscopy was then used to investigate the physical effects of the grinding process on the fly ash particles in order to identify the mechanism by which grinding leads to improved concrete properties.

Lime - Fly Ash / Rice Husk Ash에 의한 해성퇴적토의 강도특성 개선 (Strength Improvement of Lime-treated Soil with Fly Ash and Rice Husk Ash)

  • 민덕기;황광모;이경준;김현도
    • 한국지반공학회:학술대회논문집
    • /
    • /
    • pp.55-62
    • /
    • 2000
  • In this paper, a laboratory investigation was carried out to estimate the strength improvement of quicklime mixture with fly ash and rice husk ash for the effective use of surplus soils, and the shear strength with curing time was estimated at lime 10 percent with the change of fly ash and rice husk ash content. The effect of strength improvement has been established through the change of fly ash and rice husk ash content from the samples taken at Samsan region, Ulsan. The test results indicated that the presence of lime with fly ash and rice husk ash encouraged the stabilization efficiency of lime with fly ash and rice husk ash, and increased shear strength. Furthermore, it is necessary for inquiring into the relationship between the characteristics of strength and the chemical components.

  • PDF

Mechanochemical 표면처리한 Fly Ash 혼화 Concrete의 제조 (Fabrication of Concrete Containing Mechanochemically Surface Treated(MST) Fly Ash)

  • 이형직;구자훈;유인상;송두규;정해경;권혁병;윤상옥;이형복;이홍림
    • 한국세라믹학회지
    • /
    • v.39 no.2
    • /
    • pp.135-144
    • /
    • 2002
  • 채취 그대로의 fly ash(As Received Fly Ash, ARFA)90 wt%와 cement 10 wt%의 혼합물 ball milling 함으로서 mechanochemical processing에 의해 표면 처리한 fly ash(Mechanochemically Surface Treated Fly Ash, MSTFA)를 사용하여 fly ash 혼화 concrete의 강도 증진을 위한 연구를 수행하였다. ARFA에 ball-milling하여 particle size reduction만 발생시킨 fly ash(Ball-mill Processed Fly Ash, BPFA)혼화시의 공시체와 비교하여 동일한 fly ash의 혼화량, 동일한 재령의 압축강도 및 미세구조의 관점에서 고찰하였다. MSTFA를 혼화한 concrete 공시체의 압축강도는 ARFA를 혼화한 것보다 10-20%, BPFA를 혼화한 것보다는 2-7 wt% 상승한 값을 나타내었다. 이 같은 강도 상승은 MSTFA와 cement의 각 입자의 서로에 대한 친화성이 증대되며 이로 인하여 수화물 생성시 cement와 fly ash 입자간의 결합력이 더욱 증가하게 되어 압축강도가 증가하는 것으로 고려된다.

A Study on Physical Properties of Mortar Mixed with Fly-ash as Functions of Mill Types and Milling Times

  • Seo, Sung Kwan;Chu, Yong Sik;Shim, Kwang Bo;Jeong, Jae Hyun
    • 한국세라믹학회지
    • /
    • v.53 no.4
    • /
    • pp.435-443
    • /
    • 2016
  • Coal ash, a material generated from coal-fired power plants, can be classified as fly ash and bottom ash. The amount of domestic fly ash generation is almost 6.84 million tons per year, while the amount of bottom ash generation is 1.51 million tons. The fly ash is commonly used as a concrete admixture and a subsidiary raw material in cement fabrication process. And some amount of bottom ash is used as a material for embankment and block. However, the recyclable amount of the ash is limited since it could cause deterioration of physical properties. In Korea, the ashes are simply mixed and used as a replacement material for cement. In this study, an attempt was made to mechanically activate the ash by grinding process in order to increase recycling rates of the fly ash. Activated fly ash was prepared by controlling the mill types and the milling times and characteristics of the mortar containing the activated fly ash was analyzed. When the ash was ground by using a vibratory mill, physical properties of the mortar mixed with such fly ash were higher than the mortar mixed with fly ash ground by a planetary mill.

Influence of the Character of Fly Ash on the Fluidity of Fly Ash Cement Paste

  • Lee, Seung-Heun;Sakai, Etsuo
    • 한국세라믹학회지
    • /
    • v.47 no.5
    • /
    • pp.426-429
    • /
    • 2010
  • The Influence of the character of fly ash on the fluidity of cement paste with a polycarboxylic acid type superplasticizer was investigated in connection with the particle size distribution, unburned carbon content, specific surface area and shape of the fly ash. The fluidity of the fly ash cement paste with an added 20 vol% fly ash increases with an increasing roundness of the fly ash and it decreases with an increasing n-value of the fly ash cement. There is a linear correlation between the roundness/n-value and the fluidity of fly ash cement paste.