• Title/Summary/Keyword: 천연모래 치환율

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Mixture Proportioning Approach for Low-CO2 Lightweight Aggregate Concrete based on the Replacement Level of Natural Sand (천연모래 치환율에 기반한 저탄소 경량골재 콘크리트 배합설계 모델)

  • Jung, Yeon-Back;Yang, Keun-Hyeok;Tae, Sung-Ho
    • Journal of the Korea Concrete Institute
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    • v.28 no.4
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    • pp.427-434
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    • 2016
  • The purpose of this study is to propose a mixture proportioning approach based on the replacement level of natural sand for reducing $CO_2$ emissions from artificial lightweight aggregate concrete(LWAC) production. To assess the effect of natural sand on the reduction of $CO_2$ emissions and compressive strength of LWAC, a total of 379 specimens compiled from different sources were analyzed. Based on the non-linear regression analysis using the database and the previous mixture proportioning method proposed by Yang et al., simple equations were derived to determine the concrete mixture proportioning and the replacement level of natural sand for achieving the targeted performances(compressive strength, initial slump, air content, and $CO_2$ reduction ratio) of concrete. Furthermore, the proposed equations are practically applicable to straightforward determination of the $CO_2$ emissions from the provided mixture proportions of LWAC.

Air Content, Workability and Bleeding Characteristics of Fresh Lightweight Aggregate Concrete (굳지 않은 경량골재 콘크리트의 공기량, 유동성 및 블리딩 특성)

  • Sim, Jae-Il;Yang, Keun-Hyeok
    • Journal of the Korea Concrete Institute
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    • v.22 no.4
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    • pp.559-566
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    • 2010
  • Fifteen lightweight concrete mixes were tested to evaluate the effect of maximum size of coarse aggregate and the replacement level of natural sand on the various properties of fresh lightweight concrete. The different properties, such as water absorption against the elapsed time, pore size distribution and micro-structure of lightweight aggregates used, influencing on the workability of fresh concrete were also measured. Test results showed that the initial slump of lightweight concrete decreased with the increase of the replacement level of natural sand. The slump of all-lightweight concrete sharply decreased by around 80% of the initial slump after 30~60 minutes. The air content and bleeding rate of lightweight concrete were significantly affected by the replacement level of natural sand as well as the maximum size of coarse aggregates. Empirical equations recommended in ACI 211 and Korea concrete standard specifications underestimated the air content of the lightweight concrete, indicating that the underestimation increases with the decrease of the replacement level of natural sand. In addition, equations to predict the air content and bleeding rate of lightweight concrete were proposed based on the test results.

Mechanical Properties of Lightweight Aggregate Concrete according to the Substitution Rate of Natural Sand and Maximum Aggregate Size (천연모래 치환율과 경량 굵은 골재 최대 크기에 따른 경량 골재 콘크리트의 역학적 특성)

  • Sim, Jae-Il;Yang, Keun-Hyeok
    • Journal of the Korea Concrete Institute
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    • v.23 no.5
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    • pp.551-558
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    • 2011
  • The effect of the maximum aggregate size and substitution rate of natural sand on the mechanical properties of concrete is evaluated using 15 lightweight aggregate concrete mixes. For mechanical properties of concrete, compressive strength increase with respect to age, tensile resistance, elastic modulus, rupture modulus, and stress-strain relationship were measured. The experimental data were compared with the design equations specified in ACI 318-08, EC2, and/or CEB-FIP code provisions and empirical equations proposed by Slate et al., Yang et al., and Wang et al. The test results showed that compressive strength of lightweight concrete decreased with increase in maximum aggregate size and amount of lightweight fine aggregates. The parameters to predict the compressive strength development could be empirically formulated as a function of specific gravity of coarse aggregates and substitution rate of natural sand. The measured rupture modulus and tensile strength of concrete were commonly less than the prediction values obtained from code provisions or empirical equations, which can be attributed to the tensile resistance of lightweight aggregate concrete being significantly affected by its density as well as compressive strength.

Flowing and Strength Properties of Low Carbon Inorganic Composite Depending to Fine Aggregate Types and Replacement Ratio (잔골재 종류 및 치환율에 따른 저탄소 무기결합재의 유동 및 강도특성)

  • Park, Jong-Pil;Bae, Sang-Woo;Lee, Yun-Seong;Lee, Kang-Pil;Lee, Sang-Soo;Song, Ha-Young
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.11a
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    • pp.235-236
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    • 2011
  • This study analyzed flowing and strength properties of mortar depending to fine aggregate types and replacement ratio by using blast furnace slag, red mud, and silica fume that are industrial by products. The findings showed that higher replacement level of fine aggregate increased air content while decreased table flow. In addition, compressive strength showed that the higher replacement level was regardless of fine aggregate types, the lower strength became. Mortar substituted by the dredged sand showed high strength.

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Effect of Bottom Ash Aggregate Contents on Mechanical Properties of Concrete (콘크리트의 역학적 특성에 대한 바텀애시 골재 양의 영향)

  • Ahn, Tae-Ho;Yang, Keun-Hyeok;Ha, Jung-Soo
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.4
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    • pp.379-386
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    • 2020
  • The present study examined the effect of bottom ash aggregate contents on the compressive strength gain and mechanical properties(modulus of elasticity and rupture and splitting tensile strength) of concrete. Main test parameters were water-to-cement ratio and bottom ash aggregate contents for replacement of natural sand. Test results showed that the 28-days compressive strength of concrete and mechanical properties normalized by the compressive strength tended to decrease with the increase in bottom ash fine aggregate content. When compared with fib 2010 model equations, bottom ash aggregate concrete exhibited the following performances: lower rates of compressive strength gain at early ages but greater rates at long-term ages; slightly higher measurements for modulus of elasticity and rupture; and lower measurements for splitting tensile strength.

Mechanical Properties of Alkali-Activated Slag-Based Concrete Using Lightweight Aggregates (경량골재를 사용한 알칼리 활성 슬래그 콘크리트의 역학적 특성)

  • Yang, Keun-Hyeok;Oh, Seung-Jin;Song, Jin-Gyu
    • Journal of the Korea Concrete Institute
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    • v.20 no.3
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    • pp.405-412
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    • 2008
  • Six alkali-activated (AA) concrete mixes were tested to explore the significance and limitations of developing an environmental friendly concrete. Ground granulated blast-furnace slag and powder typed sodium silicate were selected as source material and an alkaline activator, respectively. The main parameter investigated was the replacement level of lightweight fine aggregate to the natural sand. Workability and mechanical properties of lightweight AA concrete were measured: the variation of slump with time, the rate of compressive strength development, the splitting tensile strength, the moduli of rupture and elasticity, the stress-strain relationship, the bond resistance and shrinkage strain. Test results showed that the compressive strength of lightweight AA concrete sharply decreased when the replacement level of lightweight fine aggregate exceeded 30%. In particular, the increase in the discontinuous grading of lightweight aggregate resulted in the deterioration of the mechanical properties of concrete tested. The measured properties of lightweight AA concrete were also compared, wherever possible, with the results obtained from the design equations specified in ACI 318-05 or EC 2, depending on the relevance, and the results predicted from the empirical equations proposed by Slate et al. for lightweight ordinary Portland cement concrete. The stress-strain curves of different concrete were compared with predictions obtained from the mathematical model proposed by Tasnimi. The measured mechanical properties of lightweight AA concrete generally showed little agreement with the predictions obtained from these equations.

A Study on the Phrsical and Mechanical Properties of Concrete with Ferro Copper Slag (동슬래그를 잔골재로 사용한 콘크리트의 물리.역학적 특성에 관한 연구)

  • Lee, Mun-Hwan;Lee, Sea-Hyun;Song, Tae-Hyeob
    • Journal of the Korea Concrete Institute
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    • v.15 no.3
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    • pp.361-368
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    • 2003
  • As the supply of aggregate needed in the construction site becomes difficult due to preservation of environment and exhaust of aggregate resource, a research for replacement aggregate in shortage is being actively progressed and a copper slag is also a kind of replacing aggregate. To use copper slag as fine aggregate of concrete, many studies are already conducted in each of the advanced countries and in the state of applying these at the site. In the year of 2000 a Korea industrial standard of Copper slag aggregate for concrete was established in our country so that this can be applied in the construction site. This study is to find out whether copper slag is equipped with the physical and chemical requirements for the use in concrete aggregate, and to analyze the dynamic properties of copper slag concrete that replaces 25, 50, 75, 100% of fine aggregate. Copper slag study not only satisfies the using condition of fine aggregate, but also reveals high level of physical property compared to ordinary concrete up to 50% of sand replacement rate. In the future after confirming the durability of concrete using copper slag, it is judged to be advantageous for the preservation of environment to use this as a replacement material for natural aggregate.