• Title/Summary/Keyword: Blast furnace slag cement

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Effect of Gypsum Mixture on Activation of Coal Gasification Slag (석고 혼입이 석탄가스화 슬래그의 활성화에 미치는 영향)

  • Cho, Hyeon-Seo;Kim, Min-Hyouck;Lee, Gun-Cheol;Cho, Do-Young
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.05a
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    • pp.17-18
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    • 2019
  • In this study, the initial strength reduction of coal gasification slag fine powders was confirmed through previous studies when used in cement formulations. It is also confirmed that the blast furnace slag is mixed with cementitious coal blast furnace slag, which is similar to coal gasification slag, to incorporate gypsum in order to prevent initial strength deterioration. In order to analyze the reactivity of coal gasification slag by desulfurization gypsum, the formation of hydrates and their reactivity at early ages were confirmed by electron microscope. In order to confirm the reactivity, the gypsum samples were prepared with unincorporated type and 2% mixed type. Experimental results showed that 2% of the desulfurized gypsum specimens reacted more actively than the uninjured ones.

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Chemical Attack and Carbonation Properties of Latex-Modified Concrete Using Blast-furnace Slag (고로(高爐)슬래그 미분말(微粉末)을 사용(使用)한 라텍스개질(改質) 콘크리트의 화학적(化學的) 침식(侵蝕) 및 탄산화 특성(特性))

  • Hong, Chang-Woo;Jeong, Won-Kyong;Sim, Do-Sik
    • Resources Recycling
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    • v.17 no.5
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    • pp.11-18
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    • 2008
  • The purpose of this study was to evaluate the effects of blast-furnace slag on chemical attack and carbonation of latex-modified concrete (LMC) and ordinary portland cement concrete as slag contents. Main experimental variables were performed latex contents (0%, 15%) and slag contents (0%, 30%, 50%). The compressive strengths, chemical attacks resistance and carbonation depth were measured to analyze the characteristic of the developed LMC and BS-LMC(latex-modified concrete added blast-furnace slag) on hardened concrete. The test results showed that compressive strength of BS-LMC with blast-furnace slag content 30% was quite similar to it of OPC without slag content. The structural quality deterioration was concerned when blast slag content was up to 50%. However, carbonation restraint of BS-LMC with blast-furnace slag 30% was bigger then that of opc. Also, the effects of added latex on OPC and BS-LMC were increased on the carbonation restraint and chemical attacks resistance.

An Experimental Study on the Setting Time and Compressive strength of Mortar using Ferronickel Slag Powder (페로니켈슬래그 미분말을 사용한 모르타르의 응결시간 및 압축강도특성에 관한 실험적 연구)

  • Kim, Young-Uk;Kim, Do-Bin;Choi, Se-Jin
    • Journal of the Korea Institute of Building Construction
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    • v.18 no.6
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    • pp.551-558
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    • 2018
  • This study evaluate the fluidity and hardening properties of mortar by replacement ratio of ferronickel slag powder to estimate the applicability of ferronickel slag powder for cement replacement materials. Ferronickel slag powder was replaced by 0, 5, 10, 15 and 20% of the cement weight. In addition, blast furnace slag powder and fly ash were also used for comparing with the mixtures using ferronickel slag powder. As the test results, the micro-hydration heat of the mixture containing the ferronickel slag powder was lower than that of the mixtures containing the same amount of blast furnace slag powder and fly ash. The flow of the sample with ferronickel slag powder was relatively higher than the other mixtures. In all ages, the compressive strength of the mixture with ferronickel slag powder and fly ash was similar to that of the mix containing only fly ash. In case of drying shrinkage, the mixture containing ferronickel slag powder exhibited lower drying shrinkage than the mixture using blast furnace slag powder, and similar to the mixture containing fly ash.

Early Hydration of Portland Cement-Blast furnace Slag System by Impedance Techniques (임피던스 측정법을 이용한 포틀랜드 시멘트 -고로 슬래그계의 초기수화)

  • 송종택;김훈상;황인수
    • Journal of the Korean Ceramic Society
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    • v.39 no.1
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    • pp.99-107
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    • 2002
  • Impedance Spectroscopy (IS) has been used to study microstructure and hydration mechanism of cement pastes. In this work, the early hydration behaviour of portland cement paste with different blame values and contents of blast-furnace slag was investigated by IS. As slag was added to portland cement, the values of $R_{t(s+1)}$ (the solid-liquid phase resistance) and $R_{t(int)}$ were decreased in the early hydration period. It showed that hydration of cement paste containing slag was slower than it of the reference cement paste. As the content of slag was increased, the values of $R_{t(s+1)}$ was decreased. Furthermore, the diameter of semicircle, $R_{t(int)}$ observed at 72 hours was decreased with the increment of slag content. However, the values of $R_{t(s+1)}$ and $R_{t(int)}$ were increased with blame value of slag from the early hydration period.

Density and Strength Properties of according to the Gypsum replacement of Lightweight Matrix based on Blast Furnace Slag (고로슬래그 기반 석고를 사용한 경량 경화체의 밀도 및 강도 특성)

  • Kim, Weon-Jeong;Lee, Seung-Ho;Park, Sun-Gyu;Lee, Sang-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.05a
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    • pp.169-170
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    • 2015
  • This study is the experiment for manufacturing the Lightweight non-cement matrix based on the blast furnace slag, paper ash. Materials like cement and blowing agent in foamed concrete is replaced by by-products fro blast furnace slag and paper ash. Further, the experiment was performed by replacing alkali with nature gypsum and α type gypsum by (0, 5, 10, 15, 20) of weight of alkali (wt.%) in order to reduce the amount of expensive alkali-activator. Consequently, in the case of the density, plain showed the lowest density and it seems that specimen adding nature gypsum 5% has the best compressive strength and flexural strength. It is detemined that the strength is lowered in accordance with the α type gypsum replacement ratio is higher. The research that it can supplement the further intensity seems to be needed.

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Effect of Steam Curing on Compressive Strength of Slag Binder Concrete (증기양생이 고로슬래그 콘크리트의 압축강도에 미치는 영향)

  • Lim, Byung-Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.8
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    • pp.338-343
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    • 2017
  • In this study, blast furnace slag powder was used in concrete to help reduce carbon dioxide emissions and to recycle industrial waste. Blast furnace slag powder is a byproduct of smelting pig iron and is obtained by rapidly cooling molten high-temperature blast furnace slag. The powder has been used as an admixture for cement and concrete because of its high reactivity. Using fine blast furnace slag powders in concrete can reduce hydration heat, suppress temperature increases, improve long-term strength, improve durability by increasing watertightness, and inhibit corrosion of reinforcing bars by limiting chloride ion penetration. However, it has not been used much due to its low compressive strength at an early age. Therefore, this study evaluates the effects of steam curing for increasing the initial strength development of concrete made using slag powder. The relationship between compressive strength, SEM observations, and XRD measurements was also investigated. The concrete made with 30% powder showed the best performance. The steam curing seems to affect the compressive strength by destroying the coating on the powder and by producing hydrates such as ettringite and Calcium-Silicate-Hydrate gel.

Mechanical and Electrical Properties of Low-Cement Mortar Using a Large Amount of Industrial By-Products (산업부산물을 다량활용한 저시멘트 모르타르의 역학적·전기적 특성)

  • Kim, Young-Min;Im, Geon-Woo;Lim, Chang-Min;Lee, Gun-Cheol
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.43-44
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    • 2023
  • This study evaluated the mechanical and electrical properties of low-cement mortar using a large amount of industrial by-products to reduce carbon emissions from the cement industry. As types of industrial by-products, blast furnace slag and fly ash, which are representative materials, were used, and ultra-high fly ash was mixed and evaluated to solve the problem of initial strength loss. In addition, in order to evaluate the electrical properties, 1% of MWCNT was incorporated relative to the powder mass. As experimental items, the compressive strength was measured on the 1st, 3rd, 7th and 28th days of age, and the rate of change in electrical resistance was measured on the 28th day of age. As a result of the experiment, the initial strength of the test specimen mixed with blast furnace slag and fly ash was significantly lower than that of 100% cement, and the specimen mixed with blast furnace slag showed strength equal to that of cement at 28 days of age. As an electrical characteristic, the electrical resistance was reduced when the load was loaded, and this reason is judged to be the effect of improving the conductivity as the connection between CNTs is narrowed by the compressive load.

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A Study on Sand Cementation and its Early-Strength Using Blast Furnace Slag and Alkaline Activators (고로슬래그와 알칼리 활성화제를 이용한 모래 고결 및 조기강도에 관한 연구)

  • Park, Sung-Sik;Choi, Sun-Gyu
    • Journal of the Korean Geotechnical Society
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    • v.29 no.4
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    • pp.45-56
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    • 2013
  • In this study, a blast furnace slag with latent hydraulic property is used to cement granular soils without using Portland cement. When the blast furnace slag reacts with an alkaline activator, it can cement soils. The effect of amounts of blast furnace slag and types of alkaline activator on soil strength was investigated for resource recycling. Four different amounts of slag and six different activators (two naturals and four chemicals) were used for preparing specimens. The specimens were air-cured for 3 or 7 days and then tested for unconfined compressive strength (UCS). The UCS of cemented sand with slag increased, in the order of specimens mixed with potassium carbonate, calcium hydroxide, sodium hydroxide and potassium hydroxide. Chemical alkaline activator was better than natural alkaline activator. The maximum UCS of 3-days cured specimens was 3 MPa for 16% of slag with potassium hydroxide, which corresponded to 37% of one with 16% of high-early strength portland cement. As the amount of slag increased, the UCS and dry density of a specimen increased for all alkaline activator cases. As the curing time increased from 3 days to 7 days, the UCS increased up to 97%. C-S-H hydrates were found in the cemented specimens from XRD analyses. Cement hydrates were more generated with increasing amount of slag and they surrounded sand particles, which resulted in higher density.

The Experimental Study on the Heat Hydration Properties of Concrete According to Binder Conditions (결합재 조건에 따른 콘크리트의 수화발열 특성에 관한 연구)

  • Choi, Sung-Woo;Jo, Hyun-Tae;Ryu, Deuk-Hyun
    • Journal of the Korea Concrete Institute
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    • v.18 no.6 s.96
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    • pp.769-776
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    • 2006
  • Recently, owing to the development of industry and the improvement of building techniques, concrete structures are becoming larger and higher. In hardening of these large connote structures, the heat of hydration gives rise to considerable thermal stress depending on the size and environmental condition of concrete, which might cause thermal cracking. Especially, the crack may cause severe damage to the safety and the durability of concrete structure. This study investigates the thermal properties of concrete according to several binder conditions, such as OPC, Belite rich cement(BRC), slag cement(SC), blast furnace slag(B) added cement fly ash(F) added cement and blast-furnace-slag and fly ash added cement. As a result of this study, the properly of concrete is most better BRC than others, and fly ash(25%) added cement and BFS(35%)-fly ash(15%) added cement gets superior effect in the control of heat hydration. But synthetically considered properties of concrete, workablity, strength heat hydration, etc, it is more effective to use mineral admixture. Especially, to be used Blast Furnace slag is more effective.

Development of Fly Ash/slag Cement Using Alkali-activated Reaction(2) - Reaction products and microstructure - (알칼리 활성반응을 이용한 플라이 애쉬/슬래그 시멘트 개발(2) - 반응생성물과 미세구조 -)

  • Park, Sang-Sook;Kang, Hwa-Young;Han, Kwan-Su
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.7
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    • pp.810-819
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    • 2007
  • Investigation of alkali activation of fly ash and blast furnace slag was carried out using waterglass and sodium hydroxide. XRD, FTIR, $^{29}Si$ and $^{27}Al$ NMR, TGA and SEM were used to observed the reaction products and microstructure of the fly ash/slag cement (FSC) pastes. The reaction products were amorphous or low-ordered calcium silicate hydrate and aluminosilicate gel produced from alkali activation of blast furnace slag and fly ash, respectively. On the basis of this investigation, waterglass solution with a modulus(Ms) of 1.0 and 1.2 is recommended for alkali activation of fly ash and blast furnace slag. Morphology of FSC pastes alkali-activated with Ms of 1.0 and 1.2 shows a more solid and continuous matrix due to restructuring of gel-like reaction products from alkali-activated fly ash and blast furnace slag together with another hydrolysis product(i.e., silica gel) from water glass.