• Title/Summary/Keyword: BFS

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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.

Effect of alkaline activators on the fresh properties and strength of silico-manganese fume-slag activated mortar

  • Nasir, Muhammad;Johari, Megat Azmi Megat;Yusuf, Moruf Olalekan;Maslehuddin, Mohammed;Al-Harthi, Mamdouh A.
    • Advances in concrete construction
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    • v.10 no.5
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    • pp.403-416
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    • 2020
  • This study investigated the effect of alkaline activators - NaOHaq (NH) (NH: 0-16 M) and Na2SiO3aq (NS) (NS/NH: 0-3.5) in the synthesis of silico-manganese fume (SMF) and ground blast furnace slag (BFS) blended alkali-activated mortar (AASB). The use of individual activator was ineffective in producing AASB of sufficient fresh and hardened properties, compared to the synergy of both activators. This may be attributed to incomplete dissolution and condensation of oligomers required for gelation of the binder. An inverse relationship was noted among the fresh properties and the NH concentration or NS/NH ratio. This was influenced by the dissolution and condensation of silicate monomers under polymerization process. The maximum 28-day strength of ~45 MPa, setting time of 60 min and flow of 182 mm was obtained with the use of combined activators (10M-NH and NS/NH=2.5). The combined activators at NS/10M-NH=2.5 constituted SiO2/Na2O, H2O/Na2O and H2O/SiO2 molar ratio of 1.61, 17.33 and 10.77, respectively. This facilitated the formation of C-S-H, C/K-A-S-H and C-Mn-S-H in the framework together with an increase in the crystallinity due to more silicate re-organization within the aluminosilicate chain. On comparison of the high concentrated with mild alkali synthesized product, it revealed that the concentration of OH- and Si monomers together with alkali metals influenced the dissolution of precursors and embedment of the constituent elements in the polymeric matrix. These factors eventually contributed to the microstructural densification of the mortar prepared with NS/10M-NH=2.5 thereby enhancing the compressive strength.

The Properties of Internal Temperature of Paste and Concrete according to Component Ratio Variation of Ternary System Cement (3성분계 시멘트의 구성비 변화에 따른 페이스트 및 콘크리트의 내부온도 특성)

  • Kim, Yeon-Seung;Kim, Dong-Hyeok;Jee, Nam-Yong
    • Journal of the Korea Concrete Institute
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    • v.20 no.6
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    • pp.797-807
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    • 2008
  • For this study, the semi-adiabatic temperature rising test is accomplished by using ternary system cement (OPC, BFS, FA) reducing temperature crack. Two tests are conducted; one is for the paste test, and the other is for the concrete test. As the results of paste tests, using fly ash is better to reduce hydration temperature than doing blast furnace slag. In the case of the paste mixed ternary system cement, the more fly ash is mixed and the less blast furnace slag is used, the lower the temperature is. The less the mixture ratio of blast furnace slag is and the more the mixture ratio of fly ash is, the later the temperature rising velocity and descending velocity are. Besides, the temperature is lower if water/binder ratio is high. The use of ternary system cement has the retardation effect of temperature rising because the time to reach the maximum temperature is in the order of OPC100, binary system cement, and ternary system cement. From the test, the maximum temperature of concrete used ternary system cement is $8{\sim}11^{\circ}C$ lower than that of concrete used OPC100. Moreover, temperatures rising velocity and descending velocity of ternary system cement range $47{\sim}51%$ and $37{\sim}42%$ compared with OPC100. The specimen of concrete shows remarkable low internal temperature and slow temperature rising velocity and descending velocity compared with the specimen of paste because it is that temperature loss of concrete is much more than paste specimen according to aggregates.

The Feasibility Study for Utilization of Blended Cement as a Activator of Bottom Ash from Circulating Fluidized Bed Combuster Boiler (순환유동층 보일러 바텀애시의 혼합시멘트 자극제 활용을 위한 타당성 연구)

  • Park, JongTak;Jung, Gwon Soo;Kang, Chang Ho;Oh, Hongseob
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.3
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    • pp.255-262
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    • 2020
  • Blended cement with fly ash and bottom ash from Circulating Fluidized Bed Combustor boiler(CFBC) burned at a low temperature, can be high heat of hydration and abnormal setting caused by higher volumn contents of Fe2O3, free-CaO, SO3. In this study, the ground CFBC bottom ash powder mixed with blast furnace slag was used as substitute activator of gypsum and recycled iron slag was produced from mix and pulverized by ball mill to increase the recycling rate. The effect on compressive strength of cements with the mixture of original and hydrated bottom ash mixtures with BFS with small water, respectively, was analyzed, and it was found that the hydrated bottom ash activator was more effective in initial strength development. To improve the initial strength of blended cement, an activator mixed with a blast furnace slag and bottom ash mixing ratio of 5:95 and 10:90, respectively, the slag cement by about 6%, and it was analyzed to develop an initial strength similar to gypsum as a conventional activator.

The Clinical Significance of Bronchial Anthracofibrosis Associated with Coal Workers' Pneumoconiosis (탄광부 진폐증 환자에 동반된 기관지 탄분섬유화증의 임상적 의의)

  • Kim, Mi-Hye;Lee, Hong-Yeul;Nam, Ki-Ho;Lim, Jae-Min;Jung, Bock-Hyun;Ryu, Dae-Sick
    • Tuberculosis and Respiratory Diseases
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    • v.68 no.2
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    • pp.67-73
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    • 2010
  • Background: In previous study, most patients with bronchial anthracofibrosis (BAF) were non-miners, and non-occupational old aged females. However, the clinical significance of BAF in patients with coal workers' pneumoconiosis (CWP) is unknown. Methods: Among patients with CWP who transferred to our hospital for an evaluation of associated pulmonary diseases, 32 patients who had undergone a bronchofibroscopy (BFS) and chest computed tomography (CT) examination were evaluated for the association of the BAF using a retrospective chart review. Results: Nine of the 32 CWP patients (28%) were complicated with BAF. Four of the 16 simple CWP patients (25%) were complicated with BAF. According to the International Labor Organization (ILO) classification by profusion, 2 out of 3 patients in category 1, 1 out of 8 patients in category 2 and 1 out of 3 patients in category 3 were complicated with BAF. Five out of 16 complicated CWP patients were complicated with BAF. Three out of 7 patients in type A and 2 out of 5 patients in type C were complicated with BAF. CWP patients with BAF had significantly greater multiple bronchial thickening and multiple mediastinal or hilar lymph node enlargement than the CWP patients without BAF. There was no difference in the other clinical features between the CWP patients with BAF and those without BAF. Conclusion: Many CWP patients were complicated with BAF. The occurrence of BAF was not associated with the severity of CWP progression. Therefore, a careful evaluation of the airway with a bronchoscopy examination and chest CT is warranted for BAF complicated CWP patients who present with respiratory symptoms and signs, even ILO class category 1 simple CWP patients.

Hydration Properties of Cement Matrix using Electrolysis Alkaline Aqueous and Ground Granulated Blast Furnace Slag (전기분해 알칼리 수 및 고로슬래그 미분말 혼입 시멘트 경화체의 수화 특성)

  • Jung, Yoong-Hoon;Kim, Ho-Jin;Park, Sun-Gyu
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.2
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    • pp.185-190
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    • 2021
  • Cement has been used as a main material in the modern construction industry. However, it has been pointed out as a main cause of global warming due to carbon dioxide generated during manufactured. Recently, research that replacing cement substitute to industrial by-products such as Blast Furnace Slag which is by-producted in steelworks. When Blast Furnace Slag is used as a cement substitute, it shows a problem of lower initial strength, which is caused by glassy membrane on the particle surface. In this study, we used Electrolysis Alkaline Aqueous to improve the usability and problem of lower initial strength. As a result of the experiment, cement matrix using Blast Furnace Slag and Alkaline Aqueous showed initial strength and hydrate product were developed than that using general mixing water. Also, as a result of porosity analysis, It was confirmed that cement matrix using Alkaline Aqueous and Blast Furnace Slag has a tighter structure in internal porosity and porosity distribution than using general mixing water.

A Study on the Applicability of Heavyweight Waste Glass and Steel Slag as Aggregate in Heavyweight Concrete (고밀도 폐유리와 제강슬래그의 중량 콘크리트 골재로의 적용성에 관한 연구)

  • Choi, So-Yeong;Kim, Il-Sun;Choi, Yoon-Suk;Yang, Eun-Ik
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.2
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    • pp.107-115
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    • 2019
  • The many countries are facing the shortage of natural resources, and the supply of aggregates are being exhausted. To consider this situation a variety of studies were performed for the development of alternative resources. In particular, high density filler material was used for shielding radioactive waste, large amount of natural aggregates are required in order to produce filler material. Also, in order to improve the shielding performance of filler material, it is required to increase the density of the filler material. Therefore, in this study was carried out to provide basic data for expanding the feasibility of high density industrial waste resource as aggregate in heavyweight concrete. From the test results, OPC case, concrete strength decreased by using heavyweight waste glass as fine aggregate, however, it is improved by using mineral admixture as binder. Therefore, when the heavyweight waste glass and steel slag are applied to heavyweight concrete, it is desirable to use mineral admixture, especially to use BFS than FA. Meanwhile, when the steel slag was replaced as coarse aggregate of heavyweight concrete, elasticity of modulus and radiation shielding performance can be improved owing to high density of steel slag.