• Title, Summary, Keyword: admixtures

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The Freezing Temperature of Chemical Admixtures for Concrete and the Quality Vareation of Concrete Using the Frozen Admixtures (콘크리트용 혼화제의 동결온도 및 동결된 혼화제의 사용에 따른 콘크리트의 품질변화)

  • 한천구;한경익;이건철
    • Magazine of the Korea Concrete Institute
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    • v.10 no.4
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    • pp.205-212
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    • 1998
  • Frost damage of a storage tank for chemical admixtures caused by a low temperature in winter and quality deterioration of chemical admixtures have been often reported. However, there have been few regulations and researches related to the frost damage of chemical admixtures and facilities. Therefore, this paper is intend to investigate not only, the freezing points of chemical admixtures such as AE admixtures and water-reducing AE admixtures, etc., but also the quality variation of concrete used with chemical admixtures before freezing and after freeze-thaw cycles. According to the results of experiments, most chemical admixtures except anti-freezing agent and accelerating water-reducing AE admixtures should be kept from being frozen in low winter temperatures. However, full agitation of frozen chemical admixtures dose not cause the problems of concrete related to the quality of chemical admixtures.

Experimental Study on the Chloride Invasion Resistance Properties of Concrete Containing Mineral Admixtures (혼화재 혼입 콘크리트의 염화물 침투저항성에 관한 실험적 연구)

  • 유재강;김동석;이상수
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.43-48
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    • 2003
  • This paper investigate that the effect of the concrete containing mineral admixtures(pozzaolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for 3∼4 replacement ratios under W/B ratios ranged from 0.40 to 0.55. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a results, the W/B ratios, kinds of admixture and replacement ratios, water curing periods had a great effect on the migration coefficient of chloride ion, and the optimal replacement ratios of admixture had a limitation for each admixtures. Also, the addition of mineral admixtures by mass(replacement of OPC) enhanced the resistance of the mixture to chloride penetration compared with the plain concrete. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures. The compressive strength was shown related to the migration coefficient of chloride ion, the compressive strength increased with the decreasing migration coefficient of chloride ion. Below the 50MPa, the variation of migration coefficient of concrete added mineral admixtures was bigger than plain concrete.

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An Experimental Study on the Characteristics of Concrete Containing Admixtures (혼화재를 혼입한 콘크리트의 특성에 관한 실험적 연구)

  • 배수호;윤상대;박광수;신의균
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.89-94
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    • 1996
  • The purpose of this study is to investigate the workability and strength of concrete containing admixtures. For this purpose, four kinds of admixtures such as silica fume, fly ash, ground granulated blast-furnace, rice husk ash are selected and tested on the workability and strength according to the replacement ratio of them. As a result, considering their workability and strength, the optimum replacement ratio of them were obtained for each concrete containting admixtures.

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An Experimental Study on Physical Properties of Concrete using Admixtures for High Strength Concrete (고강도 콘크리트용 혼화재를 사용한 콘크리트의 물성에 관한 실험적 연구)

  • 이승한;배재길;이종석
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.203-208
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    • 1994
  • These tests were conducted to get a device high strength concrete products in factory using admixtures for high strength concrete. The superplasticzer was used to compensate low slump of base concrete keeping its slump up about $6\pm1cm$. To examine the property for strength revelation of concrete using admixtures for high strength concrete, steam and standard curing were compared each other. Test results show that admixtures for high strength concrete is effective in steam curing and compressive strength 500kgf/$\textrm{cm}^2$ is obtained at one day, 650kgf/$\textrm{cm}^2$ at 28days as added to concrete at the ratio of 10-15%, and 740kgf/$\textrm{cm}^2$ at the ratio of 30%. Therefore admixtures for high strength concrete is effective in steam curing and make it possible to get high strength concrete using only steam curing not using autoclave curing.

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An experimental study on the evaluation of chloride attack resistance in mortar and concrete mixed with pozzolanic admixtures (포졸란계 혼화재를 혼입한 모르타르 및 콘크리트의 내염해 저항성 평가에 관한 실험적 연구)

  • 박정준;김도겸;하진규
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.461-466
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    • 2000
  • To improve the quality of concrete, we usually consider the reduction of water/cement ratio, the increase of concrete cover depth and the use of mineral admixtures. Reportedly, the use of admixtures make concrete more durable and tighten against water. But, it is needed to study more about the relationship between the admixtures and the chloride ion diffusion. Therefore, in this study, we focused on the chloride ion diffusion properties of the pozzolanic admixtures such as fly-ash, slag and silica fume which are known as being useful on chloride attack resistance when mixed into mortar or concrete. Furthermore, we treed to analyze the correlation between mortar and concrete using the admixture, which is useful for analyzing chloride ion diffusion mechanism.

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Comparison of Chloride Migration Properties of Concrete Containing Mineral Admixtures by the Electrical Accelerated Migration Test (전기촉진시험을 이용한 혼화재 혼입 콘크리트의 염화물 확산성능 비교 연구)

  • 유재강;김동석;이상수;김영진
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.58-61
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    • 2003
  • This paper investigated the chloride invasion resistance properties of concrete containing mineral admixtures(pozzolanic materials such as fly-ash, ground granulated blast-furnace slage, silica fume and meta kaolin) for each replacement ratios under W/B ratios ranged from 40% to 55%. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a result, the migration coefficients of chloride ion of concrete containing mineral admixtures were shown reducing with the use of mineral admixtures, and the compressive strength was shown related to the migration coefficient. From the correlation between compressive strengths and migration coefficients, the kind and replacement ratio of mineral admixtures have a great effect on migration coefficients below 50㎫.

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Improvement of Strength in ALC using Admixtures and Grain Size (혼합재 및 입도에 따른 경량기포콘크리트의 강도특성 개선)

  • Kim, Young-Yup;Song, Hun;Lee, Jong-Kyu;Chu, Yong-Sik
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.79-82
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    • 2007
  • Recently, the use of ALC has became increasingly popular. ALC is a unique building material. Because of its cellular nature, it is lightweight, self-insulating, sound and fireproof, as well as insect and mold resistant. Furthermore, ALC is free of VOCs and various fibers associated with wood and glass wool construction. However, ALC have high water absorption, low compressive strength and popout the origin of the low surface strength in its properties. These properties make troubles under construction such as cracking and popout. Thus, this study is to improve the fundamental strength by controls of increasing of admixtures, and grain size. Admixtures make use of metakaolin, silica fume, sodium silicate and sodium hydroxide. From the test result, the ALC using admixture have a good fundamental properties compared with plain specimen. Compressive strength, specific strength and abrasion's ratio were improved depending on increasing admixtures ratio's, and grain size.

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An Experimental Study on the Engineering Properties of Ultra-High Strength Concrete according to Types of Mineral Admixtures (광물질 혼화재 종류에 따른 초고강도 콘크리트의 공학적 특성에 관한 실험적 연구)

  • Joung Hyun-Woong;Kang Hoon;Lee Sang-Soo;Song Ha-Young;Kim Eul-Yong
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.29-32
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    • 2005
  • In this study, the experiment was carried out to investigate and analyze the strenth properties and flowability of ultra-high strength concrete accroding to types of mineral admixtures. The main experimental variables were water/binder ratio 25.0, 27.5 and 30.0$\%$, water content 155, 160, 165, and 170kg/$m^{3}$ and mineral admixtures such as fly ash, silica fume and meta kaolin. According to the test results, the principle conclusions are summarized as follows. 1) In case of using admixtures, superplasticizer amount need more than plain concrete. 2) According to kinds of admixtures, the viscosity of concrete show much difference. 3) The compressive strength of concrete that use admixtures becomes low in early-age strength, but appeared by higher than plain concrete in long-term strength. 4) Meta kaolin is excellent in side but has viscosity enlargement efficiency a little. But, problem estimates that is not to make design strength 600 and 700kgf/$cm^{2}$ if use mixing condition with water-binder ratio properly.

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The Effective Control of Hot Weather Concreting by Optimum Mineral and Chemical Admixtures (혼화재 및 혼화제의 조절에 의한 서중 콘크리트의 효과적 관리)

  • Lee, Dongyule;Ham, Suyun;Oh, Taekeun
    • Journal of the Korean Society of Safety
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    • v.30 no.3
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    • pp.59-66
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    • 2015
  • The undesirable effects of elevated external temperatures at placement on the properties of the fresh and hardened concrete are discussed briefly, and the possible use of the mineral admixtures to mitigate them and the association with water-reducing and retarding admixtures in terms of the mix design which are critical for minimizing slump loss and entrained air loss are examined in this study. To investigate the effects of such the mineral and chemical admixtures on the fresh and hardened properties of concrete exposed to high temperature, a series of concrete mixtures subjected to the high temperature were carried out and then fresh and hardened properties of the mixtures were analyzed and evaluated. Based on the results, new guide lines concerning the appropriate admixtures for hot weather are suggested.

An Experimental Study on the Influence of Types of Mineral Admixtures and Cement on the Properties of Ultra-High Strength Concrete (초고강도 콘크리트의 특성에 미치는 시멘트 종류 및 혼화재 종류의 영향에 관한 실험적 연구)

  • Kim Duk-Hyun;Kang Hoon;Lee Sang-Soo;Song Ha-Young
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.261-264
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    • 2004
  • In this study, the experiment was carried out to investigate and analyze the strenth properties and flowability of ultra-high strength concrete accroding to types of mineral admixtures and cements. The main experimental variables were water/binder ratio $25.0\%$, water content $160kg/m^3$ and mineral admixtures such as fly ash, silica fume and meta kaolin. According to the test results, the principle conclusions are summarized as follows 1) In case of using admixtures, superplasticizer amount need more than plain concrete. 2) According to kinds of admixtures and cements, the viscosity of concrete show much difference. 3) The autogeneous shrinkage of ultra-high strength concrete is profitable that use admixture, and heat of hydration is desirable that apply considering countermeasure enough in the advance. 4) Meta kaolin is excellent in side but has viscosity enlargement efficiency a little. But, problem estimates that is not to make design strength to and $70N/mm^2$ if use mixing condition with water-binder ratio properly.

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