• Title/Summary/Keyword: GGBFS

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Changes in Cement Hydrate Characteristics and Chloride Diffusivity in High Performance Concrete with Ages (재령에 따른 고성능 콘크리트의 수화 특성치와 염화물 확산성 변화)

  • Koh, Tae-Ho;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.6
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    • pp.9-17
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    • 2019
  • Cement hydrates and the related characteristics change with ages, and the behaviors are much related with chloride diffusion. In this work, 30% replacement ratio with FA(Fly Ash) and GGBFS(Ground Granulated Blast Furnace Slag) are considered for concrete with three levels of W/B (Water to Binder ratio) and 2 years of curing period. Chloride diffusion coefficients from accelerated condition are obtained at 5 measurement period (28days, 56days, 180days, 365days, and 730days), and the results are compared with porosity, binding capacity, and permeability from program-DUCOM. The similar changing pattern between chloride diffusion and permeability is observed since permeability is proportional to the square of porosity. Curing period is grouped into 4 periods and the changing ratios are investigated. Cement hydrate characteristics such as porosity, permeability, and diffusion coefficient are dominantly changed at the early ages (28~56 days), and diffusion coefficient in OPC concrete with low W/B continuously changes to 180days.

Effect of Fineness of GGBS on the Hydration and Mechanical Properties in HIGH Performance HVGGBS Cement Paste (고성능 하이볼륨 슬래그 시멘트 페이스트의 고로슬래그 미분말 분말도에 따른 수화 및 강도 특성)

  • Choi, Young Cheol;Shin, Dongcheol;Hwang, Chul-Sung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.5
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    • pp.141-147
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    • 2017
  • Recently, lots of researches on concrete with high volume mineral admixtures such as ground granulated blast-furnace slag(GGBS) have been carried out to reduce greenhouse gas. The high volume GGBS concrete has advantages such as low heat, high durability, but it has a limitation in practical field application, especially low strength development in early ages. This study investigated the compressive strength and hydration characteristics of high performanc and volume GGBS cement pastes with low water to binder ratio. The effects of fineness($4,330cm^2/g$, $5,320cm^2/g$, $6,450cm^2/g$, $7650cm^2/g$) and replacement(35%, 50%, 65%, 80%) of GGBS on the compressive strength, setting and heat of hydration were analyzed. Experimental results show that the combination of high volume slag cement paste with low water to binder ratio and high fineness GGBS powder can improve the compressive strength at early ages.

Effect of Fineness Levels of GGBFS on the Strength and Durability of Concrete (콘크리트의 강도 및 내구성에 대한 고로슬래그미분말 분말도의 영향)

  • Lee, Seung Tae
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.4
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    • pp.1095-1104
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    • 2014
  • This paper presents the results of experimental work on both strength characteristics and durability of concrete or mortar having 50% ground granulate blastfurnace slag(GBS) with different fineness levels (4,450, 6,000 and $8,000cm^2/g$). Compressive and split tensile strength test results indicated that the concrete with a higher fineness level of GBS exhibited a better strength development due to the acceleration of latent hydraulic property at the later curing stage compared with ordinary portland cement concrete. Meanwhile, it was found that a higher fineness level of GBS showed some negative effects on the resistance against freezing-thawing action. However, incorporation of GBS to concrete, irrespective of fineness levels, significantly enhanced the chloride ions penetration resistance. The resistance against sulfate attack of mortar with GBS was greatly dependent on the attacking sources from sulfate environments.

Shear Behavior of RC Beams Using Alkali Activated Slag Concrete (알칼리 활성 슬래그 콘크리트를 사용한 RC 보의 전단거동)

  • Choi, Sung;Lee, Kwang-Myong;Yoo, Sung-Won
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.3 no.1
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    • pp.58-63
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    • 2015
  • Several researches on cement zero concrete using alkali-activators have been conducted to investigate its fundamental material properties such as slump, strength and durability, however, research on the structural behavior of relevant members involving the elastic modulus, stress-strain relationship is essential for the application of this cement zero concrete to structural members. In this paper the shear behavior of reinforced concrete beams using 50 MPa-alkali activated slag concrete was experimentally evaluated. To achieve such a goal, six reinforced concrete beam specimens were fabricated and their shear behaviors were observed. The maximum difference between test results and analysis results in crack shear stress for beam specimens without stirrups is 31%, while that for beam specimens with stirrup is 15%. Furthermore, it is also found that the shear strength of alkali activated slag concrete is by 22~57% greater than the nominal shear strength calculated by design code, implying that shear design equations would provide conservative results on the safety side.

Properties of Ground Solidification Materials using Vietnam CFBC Fly Ash (베트남 CFBC 플라이애시를 사용한 지반고화재의 특성)

  • Kim, Keeseok;Lee, Jaewon;Lee, Dongwon;Yu, Jihyung;Hoang, Truong Xuan;Minh, Ha;Min, Kyongnam
    • Resources Recycling
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    • v.27 no.3
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    • pp.39-47
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    • 2018
  • According to Vietnam government establishes additional coal-fired power plants to secure generation capacity, emission of ashes is accelerating and processing them is urgent issue. This study targeted utilize fly ashes that occurred in circulating fluidized bed combusion (CFBC) power plant to use ground solidification materials. CFBC fly ashes are used to make solidification with ground granulated blast furnace slag (GGBFS), gypsum and cement. Then produced specimens by mixing with soft ground soil to confirm mixing effect of fly ash in solidification. As a result it was possible to find mixture design that is satisfied 3 MPa compressive strength in age 28 days and reduce weight loss rate over 50% in acid immersion test than plain specimens that using only ordinary portland cement.

Modeling on Compressive Strength in High Performance Concrete Using Porosity (공극률을 이용한 고성능 콘크리트의 압축강도 특성 모델링)

  • Lee, Hack Soo;Kwon, Seung Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.6
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    • pp.124-133
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    • 2012
  • Compressive strength in concrete increases with time. Regression analysis with time is conventionally performed for strength evaluation and prediction. In this study, hydrate amount is assumed as a function of hydration rate and porosity, and modeling on compressive strength is carried out considering decreasing porosity with time, which does not need the regression analysis with time. For twenty one mix proportions of HPC (High Performance Concrete), DUCOM (FE program) which can simulate the behavior in early aged concrete is utilized, and porosity from each mix proportions is obtained with time. For HPC with OPC (Ordinary Portland Cement) concrete, modeling on compressive strength is performed considering hydration rate, unit content of cement, and porosity with time. For HPC with mineral admixtures, a long-term parameter which can handle long-term strength development is additionally considered. From the comparison with the previous test results, the applicability of the proposed model is verified.

Sulfate Attack According to the Quantity of Composition of Cement and Mineral Admixtures (시멘트 화학성분(C3A)과 무기 혼화재에 따른 황산염 침투 특성)

  • Ahn, Nam-Shik;Lee, Jae-Hong;Lee, Young-Hak
    • Journal of the Korea Institute of Building Construction
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    • v.11 no.6
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    • pp.547-556
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    • 2011
  • The primary factors affecting concrete sulfate resistance are the chemical composition of the Portland cement, and the chemistry and quantity of mineral admixtures. To investigate the effect of those on the sulfate attack, the testing program involved several different mortar mixes using the standardized test, ASTM C1012. Four different cements were evaluated, including one Type I cement, two Type I-II cements, and one Type V cement. Mortar mixes were also made with mineral admixtures, as each cement was combined with three different types of mineral admixtures. One Class F fly ash, one Class C fly ash, and one ground granulated blast furnace slag (GGBFS) were added in various percent volumetric replacement levels. Expansion measurements were taken and investigated with the expansion criteria recommended by ASTM.

Analysis Technique for Chloride Penetration in High Performance Concrete Behavior Considering Time-Dependent Accelerated Chloride Diffusivity (촉진염화물 확산계수의 시간의존성을 고려한 고성능 콘크리트의 염화물 침투 해석기법)

  • Kwon, Seung-Jun;Park, Sun-Gyu
    • Journal of the Korea Concrete Institute
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    • v.25 no.2
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    • pp.145-153
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    • 2013
  • Recently, accelerated chloride diffusion coefficients are used for an evaluation of chloride behavior. Similar as apparent diffusion coefficients, accelerated diffusion coefficients decrease with time. In this study, decrease in diffusion coefficient with time is simulated with porosity. Utilizing DUCOM-program, porosities from 15 mix proportions are obtained and diffusion coefficients are modelled with regression analysis of porosity for 270 days. Considering non-linear binding capacity which means the relation between free and bound chloride ion, chloride behavior in high performance concrete is evaluated. Through utilizing the previous test results for concrete under chlorides for 180 days, the applicability of the proposed technique is verified. The proposed technique is evaluated to reasonably predict the chloride behavior in concrete with various w/c (water to cement) ratios and mineral admixtures (GGBFS and FA). It is also shown that decrease in chloride diffusion should be considered for chloride prediction in concrete with mineral admixture since it has very clear decrease in diffusivity with time.

Characteristics of Diffusion Coefficient of High Performance Concrete using GGBFS for Road Structures by Accelerating Test Method (슬래그 미분말 혼입률에 따른 도로구조물용 고성능 콘크리트의 압축강도 및 촉진 염소이온 확산 특성)

  • Han, Seong-Woo;Kim, Hong-Sam;Lee, Chan-Young;Cheong, Hai-Moon;Ahn, Tae-Song
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.885-888
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    • 2008
  • In recent years, the terminology "High-Performance Concrete(HPC)" has been introduced into the construction industry. Most high-performance concretes have a high cementitious content and a low water-cementitious material ratio. The proportions of the individual constituents vary depending on local preferences and local materials. Therefore, many trial batches are usually necessary before a successful mix is developed. The objective of this experiments is to investigate the fundamental properties of high performance concrete based binary cimentitious materials such as ordinary portland cement and ground granulated blast furnace slag. The results from the study will be utilized as the basic data and guideline in making standard mixproportions and the manufacture, construction work and quality control of HPC

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Study on the Quality Characteristics of High-strength Concrete Using LCD Industrial Waste (LCD 산업부산물을 이용한 고강도 콘크리트의 품질 특성에 관한 연구)

  • Kim, Dong-Jin;Park, Seung-Hee;Choi, Sung;Han, Yang-Su
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.4
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    • pp.650-657
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    • 2021
  • Alkali activators that stimulate mineral compounds are expensive materials, but in order to replace industrial products of high alkali in gredien ts, both product an d econ omic feasibility must be satisfied. In this study, alkali in dustrial waste(LW) from the LCD man ufacturin g process were used for the purpose of alkali active reaction of GGBFS for high stren gth concrete over 50MPa. Concrete mixed with LW had reduced workability, but it had the characteristic of increasing compressive strength. Analysis using ACI 209 Compressive Strength Model Equation was made to compare the changes in strength coefficients according to LW mixing. The durability test of concrete, such as Chloride Penetration Resistance and carbonation resistance, also showed excellent performance. In the Adiabatic temperature rise test results, the concrete mixed with LW had the effect of accelerating the initial hydration heat. However, the final Adiabatic temperature rise was not significantly affected by the mixing of LW.