• Title/Summary/Keyword: Fly ash, Carbonation

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Evaluation of Engineering Properties in Early-Age Concrete with TDFA (TDFA를 혼입한 초기재령 콘크리트의 공학적 특성 평가)

  • Park, Jae-Sung;Park, Sang-Min;Kim, Hyeok-Jung;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.5
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    • pp.1-8
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    • 2016
  • This paper presents an evaluation of engineering properties in TDFA(Tire Derived Fuel Ash)- based concrete in early age. Concrete containing 0.5 of w/b(water to binder) ratio and 20% of FA(Fly Ash) replacement ratio are prepared, and FA content are replaced with TDFA from 3% to 12% for evaluating the effect of TDFA on fresh and hardened concrete properties. With higher than 6% of TDFA replacement ratio, workability is significantly worsened but it is improved with more SP(Super plasticizer) and AE(Air Entrainer) agent. Concrete with 6~12% of TDFA shows reasonable strength development and better resistance to carbonation and chloride attack in spite of early-aged condition. However concrete with 6% TDFA shows poor resistance to freezing and thawing action due to insufficient air content. If air content and workability are obtained, replacement of TDFA to 12% can be used for concrete with FA.

Coating Effect by Applying Refined Cooking Oil on the Carbonation of High Volume Admixture Incorporating Concrete (정제유지류 도포가 혼화재 다량치환한 콘크리트의 탄산화에 미치는 영향)

  • Kim, Tae-Cheong;Choi, Young-Doo;Baek, Byung-Hoon;Shin, Dong-An;Oh, Seon-Kyo;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2014.05a
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    • pp.146-147
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    • 2014
  • In this study, as the resistance of the carbonation for high volume admixture incorporating concrete, coating effect of using refined cooking oil in the surface of high volume admixture incorporating concrete has been tested. The following results could be made as the conclusion. For the fresh concrete, the slump and air content has been identified as satisfying the target range. For the hardened concrete, comparing with specimen of Plain, specimen with coating showed better long age compressive strength. For the carbonation speed, the specimen of FA30 showed highest speed and the specimen of BS60 showed higher speed than specimen of Plain. For all the specimens coated with RCO, as the decrease of capillary pores inside the concrete, the carbonation speed has been obviously decreased and with even better effect than using PEP coating. It could be identified that specimens with coating by RCO showed good effect on refrain the speed of carbonation.

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Effects of Combined Attacks on Chloride Diffusivity in Concrete (콘크리트내의 염소이온 침투특성에 미치는 복합 열화작용의 영향)

  • 오병환;강의영;정상화;장승엽;인광진;서정문
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.665-670
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    • 2001
  • The studies on chloride diffusion of concrete have been done so far by many researchers. However, there are few studies that present the effects of other attacks on chloride diffusion properties. Therefore, in this study the experiments are carried out to show the effects of combined attacks, such as carbonation, sulfate attacks, on chloride diffusivity in concrete. The specimens are made by varying cement type and replacement ratio of fly ash. The results show that cement type and replacement of fly ash do not affect greatly chloride diffusion properties. And concrete treated by combined attacks show a little higher chloride content than those treated by chloride solution only. Therefore, the effects of these factors should be taken into account in predicting the penetration of chloride ion in concrete.

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Strength Development and Durability of Geopolymer Mortar Using the Combined Fly ash and Blast-Furnace Slag (플라이애시와 고로슬래그 미분말을 혼합 사용한 지오폴리머 모르타르의 강도발현 및 내구성)

  • Ryu, Gum-Sung;Koh, Kyung-Taek;Lee, Jang-Hwa
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.1 no.1
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    • pp.35-41
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    • 2013
  • In this study, we investigated the strength development and durability of geopolymer mortar using blast furnace slag only, and admixed with blast-furnace slag and fly ash as cementious materials in oder to develop cementless geopolymer concrete. In order to compare with the geopolymer mortar, the normal mortar using ordinary portland cement was also test. In view of the results, we found out that strength development, the resistance to freezing-thawing of the geopolymer mortar have better than the mortar using ordinary portland cement. Especially, using the combined with blast furnace slag and fly ash develop high strength of above 60 MPa, and improve the resistance of freezing-thawing of approximately 20%, but promote the velocity of carbonation of 2.2~3.5 times.

Application of Alkali-Activated Ternary Blended Cement in Manufacture of Ready-Mixed Concrete (알칼리 활성화 3성분계 혼합시멘트의 레미콘 적용 시험)

  • Yang, Wan-Hee;Hwang, Ji-Soon;Lee, Sea-Hyun
    • Journal of the Korea Institute of Building Construction
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    • v.17 no.1
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    • pp.47-54
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    • 2017
  • Cement industry is typical carbon-emission industry. If the industrial by-products(granulated blast-furnace slag (GGBFS), fly ash, etc.) are used a large amount, it might be able to reduce cement consumption and mitigate carbon emissions. In this case, however, decrease of early strength is relatively large. Therefore, there is a limitation in increase of the amount of substitute. Considering these circumstances, it would be a good solution to reduce carbon emissions in cement industry to improve the performances of mixed cement through proper alkali-activation in Portland blended cement using GGBFS or fly ash. Therefore, this study prepared concrete in ready-mixed concrete manufacturing facilities with an addition of a binder which used 2.0% modified alkali sulfate activator after mixing Portland cement, GGBFS and fly ash in the ratio of 4:4:2 and assessed its basic properties. The results found the followings: The use of modified alkali-sulfate activator slightly reduced slump and shortened setting time. As a result, bleeding capacity decreased while early strength improved. In addition, there is no big difference in carbonation resistance. It appears that there should be continued experiments and analyses on the related long-term aged specimens.

Properties of non-cement mortars with small addition of alkali activator using fly ash and fused waste slag (석탄회 및 용융폐기물 슬래그에 소량의 알칼리 활성화제를 첨가한 무시멘트 모르타르의 특성)

  • Kim, Yootaek;Lee, Kyongwoo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.25 no.6
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    • pp.257-262
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    • 2015
  • Recently the world wide efforts reduce occurrence of $CO_2$; global warming main reason. The aim of this study is to improve recycling rate of the fly ash (FA) and fused waste slag (FWS) from the power plant and to carbonate under supercritical condition ($40^{\circ}C$, $80kgf/cm^2$ pressure, 60 min) for $CO_2$ fixation. Specimens of mortar with various mixing ratios of FA, FWS (from 100:0 to 20:80 in 5 steps of 20 % reduction each time), distilled water and 3 M NaOH alkali activators were prepared. As a result, the proportion of weight change ratio increases with CaO content, to 12 % after carbonation under the supercritical condition. There is difference of compressive strength between the carbonated and the alkali activator mortar specimens. The stabilization of $CO_2$ fixation through carbonation which could confirm the applicability of the eco-friendly materials without loss of compressive strength.

Properties of Engineering and Durability Concrete with Fly-ash and Blast Furnace Slag in Normal Strength Level (플라이애시 및 고로슬래그 첨가율에 따른 일반강도영역 콘크리트의 공학적 특성 및 내구성)

  • Kim, Gyu-Yong;Shin, Kyoung-Su;Lim, Chang-Hyuk;Nam, Jeong-Soo;Kim, Moo-Han
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.1
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    • pp.103-110
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    • 2010
  • Recently, reducing usage of cement and using by-product of industry such as blast furnace slag and fly-ash have been increased to reduce $CO_2$ gas emission. That apply to construction. As a result, reduction of environmental stress and recycling of resources are expected. In this study, as basic study to the reuse of resources and reduce Environmental Load, comparing and analyzing hardening characteristics and durability as using the blast furnace slag and fly-ash, examining concrete characteristics substituted the three elements for the blast furnace slag and fly-ash and evaluating the relationship as binder. Through this, it want to provide the basic data for mass utilization. Blast furnace slag powder and replaced at fly-ash compressive strength of concrete in the strength of the initial seven days material age lower level of expression significantly compared to the concrete, but, 28 days after the similar or higher compressive strength than the concrete expression of the was. In addition, the reserves replacement of blast furnace slag powder salt injury increasing resistance are seen improvements, according to the conventional blast furnace slag powder study by the chloride ions on the surface of the concrete are improved being fixation salt injury resistance is considered.

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CO2 Emission and Storage Evaluation of RC Underground Structure under Carbonation Considering Service Life and Mix Conditions with Fly Ash (탄산화 환경에 노출된 RC 지하구조물의 내구수명과 플라이애쉬 배합 특성을 고려한 탄소 배출 및 흡착 평가)

  • Kim, Seong-Jun;Mun, Jin-Man;Lee, Hack-Soo;Kwon, Seung-Jun
    • The Journal of the Korea Contents Association
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    • v.14 no.12
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    • pp.999-1009
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    • 2014
  • In this paper, $CO_2$ emission and storage amount are evaluated for real RC (Reinforced Concrete) underground structure considering $CO_2$ amount including material manufacturing, moving, and construction, repairing timing stage regarding extended service life. Four mix proportions with mineral admixtures are prepared and $CO_2$ diffusion coefficient are obtained based on a micro modeling. Referred to carbonation durability limit state, $CO_2$ emission and storage amount are evaluated, which shows higher initial $CO_2$ emission is caused due to larger unit content of cement and the storage increases with more rapid carbonation velocity. Furthermore various $CO_2$ concentration is adopted for simulation of $CO_2$ evaluation including measured $CO_2$ concentration (600ppm). With higher concentration of $CO_2$ outside, carbonation velocity increases. In order to reduce $CO_2$ emission through entire service life, reducing initial $CO_2$ emission through mineral admixture like fly ash is more effective than increasing $CO_2$ storage through OPC since $CO_2$ is significantly emitted under manufacturing OPC and $CO_2$ storage in cover concrete of RC structure is not effective considering initial concrete amount in construction.

An Experimental Study on the Pore Structure Property of Concrete by Carbonation (탄산화 작용에 따른 콘크리트의 세공구조 성상에 관한 실험적 연구)

  • Kim, Young-Bong;Kim, Young-Sun;Lee, Eui-Bae;Na, Chul-Sung;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.537-540
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    • 2008
  • Up to now, the RC structures have been recognized as being socially semi-permanent. But in recent years there were reports about the cases of early deterioration of RC structures. Most of all pore structure effects on the durability of concrete as well as mechanical properties of concrete. Therefore, in this study, mixing design was proportioned with the water-binder ratio 0.55 binder compositions corresponding to cement without any supplementary materials(OPC), cement with 50% blast-furnace slag replacement (BFS50), cement with 15% fly ash replacement (FA15), and ternary cement with cement, 15% fly ash, and 35% slag replacement (BFS35+FA15). And this study is to compare pore structure property of concrete by carbonation to investigate the effect of the permeation of deterioration factors such as $CO_2$ and chloride ion under the combined deterioration environments. The results showed that pore volume effects on the diffusibility of chloride ion.

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Evaluation on the Shrinkage and Durability of Cementless Alkali-Activated Mortar (무(無)시멘트 알칼리 활성(活性) 모르타르의 수축(收縮) 및 내구성(耐久性) 평가(評價))

  • Koh, Kyung-Taek;Ryu, Gum-Sung;Lee, Jang-Hwa;Kang, Hyun-Jin
    • Resources Recycling
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    • v.20 no.3
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    • pp.40-47
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    • 2011
  • In this study, we investigated the strength, shrinkage and durability of alkali-activated mortar using blast furnace slag only, and admixed with blast-furnace slag and fly ash as cementious materials in oder to develop cementless alkali-activated concrete. In order to compare with the alkali-activated mortar, the normal mortar using ordinary portland cement was also test. In view of the results, we found out that strength development, the resistance to shrinkage and freezing-thawing of the cementless alkali-activated mortar have better than the mortar using ordinary portland cement. Especially, using the combined with blast furnace slag and fly ash develop high strength of above 60 MPa, reduce shrinkage of about 40% and improve freezing-thawing durability of approximately 20%, but promote the velocity of carbonation of 2~3 times.