• Title/Summary/Keyword: Fine aggregates

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Flexural Behavior of Reinforced Recycled Aggregate Concrete Beams (순환골재를 사용한 철근콘크리트 보의 휨거동 특성)

  • Song, Seon-Hwa;Choi, Ki-Sun;You, Young-Chan;Kim, Keung-Hwan;Yun, Hyun-Do
    • Journal of the Korea Concrete Institute
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    • v.21 no.4
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    • pp.431-439
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    • 2009
  • These days the amount of demolished concrete waste has been increasing due to reconstruction and redevelopment of aged buildings. So the use of recycled aggregates is recommended to solve environmental problems. Some investigations have been carried out to study the flexural behavior of reinforced concrete beams with recycled aggregates. But these have some limitation due to the use of low quality recycled aggregates and small-scale specimens in the laboratory. The purpose of this experimental study is to evaluate the flexural behavior of simply supported RC beams subjected to four-point monotonic loading and made with recycled aggregates. Seven full-scale RC beams were manufactured with different replacement level of recycled aggregates. The main parameters of the study are combination of aggregates. From the test results, the flexural behavior of the beam is described in terms of crack patterns and failure modes. And the flexural strength of RC beam with different types of recycled coarse aggregates and recycled fine aggregates is compared with the provision of KCI code.

A Fundamental Study on Supply Status and Use Plan of Fine Aggregates (잔골재의 수급현황 및 활용방안에 관한 기초적 연구)

  • Yu Myoung Youl;Lee Sea-Hyun;Lee Hyun-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.101-104
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    • 2005
  • It analyzed the supply status of fine aggregate and find the point of issue related alternative fine aggregate through researches and interviews. The conclusions of the study are as follows. 1. Ready mixed concrete manufacture used crushed fine aggregate (15.5$\%$) and recycled fine aggregate (1.5$\%$) for alternatives aggregate than 1.3$\%$ in 1991. It is not allowed to use a recycled fine aggregate in ready mixed concrete, but they used it. 2. All alternative aggregate are satisfied the Korean Standard, But they showed low properties of mortar compared to when it replaced with natural fine aggregate. So, it is needed to make another special Korean Standard to use alternative aggregate in normal concrete by mixing method to recover the workability and compressive strength.

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Uniaxial Behavior of Reinforced Concrete Column with Recycled Fine Aggregate (순환잔골재를 치환한 철근콘크리트 기둥의 압축거동 특성)

  • Jang, Gwang-Soo;Kim, Yun-Su;Yun, Hyun-Do;Choi, Ki-Sun;You, Young-Chan;Kim, Keung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.5-8
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    • 2008
  • The use of recycled aggregates is increasing due to problems of lack of natural aggregates. But there are no appropriate design recommendations and basic data for structural members using recycled fine aggregate concrete. This paper is to evaluate compression behavior of reinforced concrete column with displacement level of recycled fine aggregate. For these purpose, four recycled fine aggregate replacement levels (0%, 30%, 60%, 100%) were considered in this paper. Four columns with 400mm${\times}$400mm in cross section are tested under axial load. Experimental results were compared using current code(KCI2007). Compressive strength of reinforced concrete columns with recycled fine aggregate showed higher than that provided in KCI 2007. The KCI provision were conservative and subsequently can be used for design of reinforced recycled fine aggregate concrete column.

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Effect of Gypsum, Popped Rice Hull and Zeolite on Soil Aggregation in Reclaimed Tideland (간척지 토양에서 석고, 팽화왕겨 및 Zeolite 처리가 토양의 입단형성에 미치는 영향)

  • Kim, Seong-Jo;Baek, Seung-Hwa;Lee, Sang-Uk;Kim, Dae-Geun;Na, Young-Joon
    • Korean Journal of Soil Science and Fertilizer
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    • v.38 no.5
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    • pp.231-237
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    • 2005
  • Gypsum treated to fine sandy loam increased the fornation of >2 mm aggregates in $1,550kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg1) and $3,100kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg2) to compare with control, Kc, at 60DAT, and bigger aggregates in general at 90DAT. The higher treatment of gypsum level, the <0.1 mm aggregates were less decreased as in Kbfg1, Kbfg2, and $6,200kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg3) and aggregates of 0.25->2 mm were increased with increasing level of gypsum with more effective in Kbfg2 and Kbfg3 at 120DAT. Gypsum treated to silt loam increased aggregates of 2.0-1.0 and 1.0-0.5 mm in $3,100kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Mbfg2) to compare with control (Mc), at 60DAT. Degrees of aggregation from 0.5-0.25 mm to >2 mm aggregates at 90DAT were distinctly higher. The higher treatment of gypsum level accelerated more aggregation of silt loam soil, and aggregates of 0.5-0.25 mm was most increased in Mbfg2 at 120DAT. Popped rice hulls treated to fine sandy loam increased aggregates of 2.0-1.0 mm in plots of $1,000kg\;10a^{-1}$ (Kbfhl) only to compare with control (Kc), at 60DAT, and aggregates of >2 mm and 2.0-1.0 mm Kbfh1 at 90DAT. At 120DAT, aggregation by popped rice hulls was most effective in Kbfbl pot. Popped rice hulls treated to silt loam increased in aggregates of >2 mm and 2.0-1.0 mm in $2000kg\;10a^{-1}$, Mbfb2 to compare with control, Mc, at 60DAT. Degrees of aggregation by popped rice hulls at 90DAT were higher in $1,000kg\;10a^{-1}$, Mbfh1, and Mbfh2, and at 120DAT was in $3,000kg\;10a^{-1}$, Mbfb3. Zeolite treatment with popped rice hulls, $1,500kg\;10a^{-1}$, increased in >2.0 mm aggregates in $1,000kg\;10a^{-1}$, Kbfbz1, $2,000kg\;10a^{-1}$, Kbfbz2, $3,000kg\;10a^{-1}$, Kbfhz3, and Mbfbz1, $1,000kg\;10a^{-1}$, Mbfbz2, $2,000kg\;10a^{-1}$, and $3,000kg\;10a^{-1}$, Mbthz3, to compare with control (Kc and Mc), at 60DAT. irrespective of soil texture. At 90DAT, >2.0-0.5 mm aggregates increased in Kbfhz1 of fine sandy loam. aggregates of >0.25 mm in $200kg\;10a^{-1}$ (Mbfbz1), $400kg\;10a^{-1}$ (Mbfhz2), $800kg\;10a^{-1}$ (Mbfhz3) of silt loam increased with the level of zeolite treatment. At 120DAT, the effect of zeolite treated to both soils showed the decrease of <0.1 mm aggregates. As the result, soil amendments for soil aggregation was more effective in the order of popped rice hulls+Zeolite > gypsum > popped rice hulls in fine sandy loam, and in the order of gypsum > popped rice huUs+zeolite > popped rice hulls in silt loam, respectively.

Evaluation of Structural Performance of RC Beams retrofitted PVA Fiber to the Change of Replacement Ratio of Recycled Fine Aggregates and Blast Furnace Slag (고로슬래그 미분말 및 순환잔골재를 적용한 PVA섬유 보강 철근콘크리트 보의 구조성능 평가)

  • Ha, Gee-Joo;Yi, Dong-Ryul;Ha, Jae-Hoon
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.8
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    • pp.3-11
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    • 2018
  • In this study, total nine R/C beams, designed by the PVA Fiber with ground granulated blast furnace slag and recycled fine aggregate were constructed and tested under monotonic loading. In the material development, micromechanics was adopted to properly select the optimized range of the composite based on steady-state cracking theory and experimental studies on the matrix and interracial properties. Experimental programs were carried out to improve and evaluate the structural performance of the test specimens: the load-displacement, the failure mode, the maximum strength, and ductility capacity were assessed. Test results showed that test specimens (BSPR-20, 40) was increased the maximum load carrying capacity by 3~6% and the ductility capacity by 9~14% in comparison with the standard specimen (BSS). And the specimens (BSPR-60, 80, 100) was decreased the maximum load carrying capacity by 0~4% and the ductility capacity by 79% in comparison with the standard specimen (BSS) respectively.

Evaluation of Structural Performance of Steel Fiber Reinforced Concrete Beams using Industrial By-products and Recycled Fine Aggregates (산업부산물과 순환잔골재를 적용한 강섬유 보강 철근콘크리트 보의 구조성능 평가)

  • Ha, Gee-Joo;Yi, Dong-Ryul;Ha, Jae-Hoon
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.11
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    • pp.11-18
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    • 2018
  • In this study, seven R/C beams, designed by the steel fiber with ground granulated blast furnace slag and recycled fine aggregate were constructed and tested under monotonic loading. In the material development, micromechanics was adopted to properly select the optimized range of the composite based on steady-state cracking theory and experimental studies on the matrix and interracial properties. Experimental programs were carried out to improve and evaluate the structural performance of the test specimens: the load-displacement, the failure mode, the maximum strength were assessed. Test results showed that test specimens (BSSR-20, 40, 60, 80) were increased the maximum load carrying capacity by 2~9% and the ductility capacity by 10~22% in comparison with the standard specimen (BSS) respectively. And the specimens (BSSR-100) was decreased the maximum load carrying capacity by 5% and the ductility capacity by 44% in comparison with the standard specimen (BSS) respectively.

An Experimental Study for Manufacture of High Quality Recycled Aggregate by Heating (가열방법을 이용한 고품질 순환골재 제조를 위한 실험적 연구)

  • Yoo, Sung-Won;Min, Gyeong-Oan;Her, Yoon;Ha, Heon-Jae;Moon, Jae-Heum
    • Journal of the Korean Society of Safety
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    • v.26 no.5
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    • pp.65-72
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    • 2011
  • The use of waste concrete can resolve the environmental pollution and shortage of natural aggregate. However, recycled aggregate includes substantial amount of cement paste. So, these aggregates are more porous, and less resistant to mechanical actions than natural aggregates. So, recently, the new manufacture processes of high quality recycled aggregates were suggested such as heating and solving to acid liquid. But the method of solving to acid liquid is not economical and produces additional environmental pollution. In this paper, for the purpose of manufacture of high quality recycled aggregates, the heating processes was added to the existing process of recycled aggregates. To find the optimum process, the experiment was performed by using the method of statistical experiment design, and the heating temperatures(4 levels : 300, 450, 600 and $750^{\circ}C$) and heating times(4 levels : 5, 20, 40, 60 minute) were main experimental variables. By the test results, the optimum manufacturing condition of coarse recycled aggregate was $600^{\circ}C$ and 40 minute, and for the fine recycled aggregate, a little heating made a satisfaction to the KS standard quality code.

Feasibility Tests for Treating Fine Suspended Solids from Mining Drainage, using Various Media by Column Methods - A Case from H Coal Mine (광산배수 부유물질 저감을 위한 다양한 여과 매질의 특성 및 적용성 평가 - H 석탄광산 배수)

  • Lee, Sanghoon;Kwon, HyukHyun;Oh, Minah;Lee, Jai-Young;Kim, DukMin
    • Journal of Soil and Groundwater Environment
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    • v.17 no.6
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    • pp.112-118
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    • 2012
  • Fine suspended solids from mine drainage draw attentions due to their potential adverse influences on the water quality, such as increasing turbidity and degrading aesthetic landscape. Currently, sand filter beds are adapted in some mine drainage treating systems. However, more efficient system is in demand, as the existing sand beds reveal some problems, such as frequent maintenance intervals. Various filtering mediums including fly ash, mine tailing aggregates and the sand were tested for improving the current system, using column experimental set-up. Mine drainage samples were collected from the current treating systems in the abandoned H coal mine. The experiment was run for 7 days. Suspended solids recorded as 100.9 mg/L and the value exceeds the current standard, 30 mg/L. Sand was proved to still be the optimum medium for the fine suspended solids, compared to fly ash and fly ash + sand. Mine tailing aggregates were placed at the exit of the columns, substituting gravels. The tailing aggregates is made by mine tailings and clay. Sand bed filters can also be improved by mixing granular activated carbon, which was found to be economical and efficient in the batch experiment, conducted at the same time.

Mix Design Procedure of Structural Concrete Using Artificial Lightweight Aggregates Produced from Bottom Ash and Dredged Soils (바텀애시 및 준설토 기반의 인공 경량골재를 활용한 구조용 콘크리트의 배합설계 절차)

  • Lee, Kyung-Ho;Yang, Keun-Hyeok
    • Journal of the Korea Institute of Building Construction
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    • v.18 no.2
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    • pp.133-140
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    • 2018
  • The objective of this study is to propose a reliable mixing design procedure of concrete using artificial lightweight aggregate produced from expanded bottom ash and dredged soil. Based on test results obtained from 25 mixes, empirical equations to determine water-to-cement ratio, unit cement content, and replacement level of lightweight fine aggregates were formulated with regard to the targeted performance (compressive strength, dry density, initial slump, and air content) of lightweight aggregate concrete. From the proposed equations and absolute volume mixing concept, unit weight of each ingredient was calculated. The proposed mix design procedure limits the fine aggregate-to-total aggregate ratio by considering the replacement level of lightweight fine aggregates, different to previous approach for expanded fly ash and clay-based lightweight aggregate concrete. Thus, it is expected that the proposed procedure is effectively applied for determining the first trial mixing proportions for the designed requirements of concrete.