• Title/Summary/Keyword: recycled fine

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A Study on the Development of Forced Carbonation Reforming Technology for Recycled Aggregates (순환골재의 강제 탄산화 개질 기술 개발을 위한 기초적 연구)

  • Lim, Myung-Kwan;Park, Won-Jun;Lee, Huck;Kim, Do-Yun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2016.05a
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    • pp.207-208
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    • 2016
  • The most important things for the production of recycled aggregates are saving energy, suppressing the generation of by-product fine particles and sustaining the performance of concrete. As solutions, this study proposes this technology of improving the performance of recycled aggregates through forced carbonation.1) It is to stimulate and carbonate the bond paste part that causes the deterioration of recycled aggregates. Particularly, the purpose of this technology is to fill and chemically stabilize pores inside the bond paste, further improving the quality of recycled aggregates with a decreased absorption rate and an enhanced aggregate strength. Ultimately, it is possible to obtain a carbonation model, depending on the paste ratio and particle-size distribution of recycled aggregates. Moreover, by calculating the optimum carbonation period through the verification of this carbonation model, it is possible to examine how much the strength is improved by the reformation of recycled aggregated.

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A Study on the Physical Properties of Recycled Fine Aggregate (by Dry and Wet Type Production formula) Mortar Using Blast Furnace Slag (고로슬래그를 사용한 건식 및 습식 재생 잔골재 모르타르의 물리적 특성에 관한 연구)

  • Shim, Jong-Woo;Lee, Sea-Hyun;Seo, Chi-Ho
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.501-504
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    • 2006
  • Recycled aggregate mortar contains plenty of calcium hydroxide to improve the strength of blast furnace slag, although the surface mortar made of recycled aggregate deteriorates adhesion to cement paste and blast furnace slag has a low initial strength. Therefore, this study assumes that the combination with both recycled aggregate and blast furnace slag will produce a better performance. The results of the experiment show that dry mortar made of recycled aggregate provides with higher strength than wet mortar does at the 3-day and 7-day age, while lower at the 28-day age. It indicates that a large amount of cement mortar made of dry recycled aggregate has deteriorated adhesion strength. The mixes with 30% and 50% of blast furnace slag and 50% and 75% of recycled aggregate provide with much better strength at the 7-day age, although they usually have latent hydraulic property at the 28-day age. It indicates that calcium hydroxide($Ca(OH){_2}$) in recycled aggregate has affected ground granulated blast furnace slag.

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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.

A Study on Physical Properties of FINEX Slag to Utilize Fine Aggregate for Concrete (콘크리트용 잔골재로 활용하기 위한 파이넥스 슬래그의 물리적 특성에 관한 연구)

  • Choi, Yun-Wang;Oh, Sung-Rok;Choi, Byung-Keol;Lee, Hoon-Ha;Choi, Wook
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.4
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    • pp.79-87
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    • 2012
  • Recently, Development of substitution aggregate is urgently needed because aggregate shortage is continuing due to the exhaustion of natural aggregate and strict restrictions of environment in construction industry. Therefore, This paper was examined the fundamental properties for application of FINEX slag by finex process as fine aggregate for concrete. Through this study, we propose the practical method of FINEX slag as fine aggregate for concrete.

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Engineering Properties of High Strength Concrete Using Lime Stone Recycling Fine Aggregate (석회암 순환잔골재를 사용한 고강도 콘크리트의 공학적 특성)

  • Han, Cheon-Goo;Kim, Hyun-Woo
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.3 no.1
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    • pp.72-79
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    • 2007
  • This study investigates the engineering properties of concrete incorporating lime stone crushed fine aggregate(Ls), which has been abandoned about 20% of total production due to the low purity. Test results showed that increase of Ls had favorable fluidity and slightly decreased air content. Bleeding capacity of all specimens was not appeared as those were high strength mixture proportion, but the specimens using more Ls accelerated initial and final setting. For the mechanical properties, specimens incorporating higher ratio of Ls, overall, resulted in increase of compressive strength, and exhibited very small inclined tendency in a dynamic elasticity modulus test In addition, for the durability properties, specimens incorporating higher Ls dramatically decreased a drying shrinkage and showed similar tendency in a frost & thaw test, as well as showing no more change in an accelerated neutralization test from the beginning. In conclusion, as it was confirmed in the experimental test, the high strength concrete applying Ls did not showed any problems in the aspects of engineering properties and mostly exhibited even more excellent quality than the specimens using natural fine aggregate.

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Characteristics of Concrete Using Coal-By-product as Fine Aggregate (석탄 부산물인 경석을 잔골재로 사용한 콘크리트의 특성)

  • In-Hwan Yang;Seung-Tae Jeong;Geun-Woo Park;Gyeong-Min Choi
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.12 no.1
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    • pp.53-62
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    • 2024
  • In this paper, an experimental study on the strengths and material properties of concrete manufactured by using coal gangue, as a fine aggregate was conducted. Experimental parameters included coal gangue aggregate contents as a replacement of fine aggregate by 50 % and 100 % (by volume) and fly ash contents. The water-binder ratio was fixed at 0.38. In addition, 30 % of the OPC binder was replaced with fly ash in some mixtures. Test of the unit weight, compressive, split tensile, and flexural tensile strength of concrete were performed and test results were analyzed. Unit weight, compressive strength, split tensile strength, and flexural tensile strength decreased as the coal recycled aggregates increased. In addition, TGA and SEM experiments, which are microstructure experiments, were conducted to analyze thermogravimetric analysis and ITZ by section.

Effect of Fine Particle Cement and Recycled Aggregates as Alkali Activator on the Engineering Properties and Micro-Structure of High Volume Blast Furnace Slag Concrete (알칼리 자극제로서 미분시멘트와 순환골재가 고로슬래그 다량치환 콘크리트의 공학적 특성 및 미세구조에 미치는 영향)

  • Han, Min-Cheol;Lee, Hyang-Jae;Han, Cheon-Goo
    • Journal of the Korea Institute of Building Construction
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    • v.13 no.6
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    • pp.602-608
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    • 2013
  • The aim of this study is to investigate experimentally the effect of the combination of fine particle cement with high Blaine fineness (FC) and recycled aggregates on the engineering properties and micro structure of high volume blast furnace slag (BS) concrete with 75% BS and 21 MPa. FC manufactured by particle classification at the plant with Blaine fineness of more than $7000cm^2/g$ was used as additional alkali activator for high volume blast furnace slag concrete made with recycled fine and coarse aggregates. FC was replaced by 15, 20 and 25% OPC. Test results showed that the incorporation of FC resulted in an increase in the compressive strength compared to BS concrete without FC by as much as 30% due to accelerated hydration and associated latent hydraulic reaction. It was found that the use of FC and recycled aggregates played an important role in activating BS for high volume BS concrete by offering sufficient alkali.

Strength and Durability Evaluation of Recycled Aggregate Concrete

  • Yehia, Sherif;Helal, Kareem;Abusharkh, Anaam;Zaher, Amani;Istaitiyeh, Hiba
    • International Journal of Concrete Structures and Materials
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    • v.9 no.2
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    • pp.219-239
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    • 2015
  • This paper discusses the suitability of producing concrete with 100 % recycled aggregate to meet durability and strength requirements for different applications. Aggregate strength, gradation, absorption, specific gravity, shape and texture are some of the physical and mechanical characteristics that contribute to the strength and durability of concrete. In general, the quality of recycled aggregate depends on the loading and exposure conditions of the demolished structures. Therefore, the experimental program was focused on the evaluation of physical and mechanical properties of the recycled aggregate over a period of 6 months. In addition, concrete properties produced with fine and coarse recycled aggregate were evaluated. Several concrete mixes were prepared with 100 % recycled aggregates and the results were compared to that of a control mix. SEM was conducted to examine the microstructure of selected mixes. The results showed that concrete with acceptable strength and durability could be produced if high packing density is achieved.

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.

An Experimental Study on Chlorine-ion and Carbonation Resistance of the Concrete Using Recycled Aggregate Mixed Fly Ash (플라이애쉬 혼입율에 따른 순환골재콘크리트의 염소이온 및 중성화 저항성에 관한 시험적 고찰)

  • Sim Jong Sung;Park Choel Woo;Park Sung Jae;Kim Kil Jung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.580-583
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    • 2004
  • Due to the tendency of increase in demolished-concrete produced by alteration and deterioration of concrete structures, recycling of those demolished-concrete is necessary to solve the exhaustion of natural aggregate, in order to save resources and protect environment. In this an experimental study herein, the Chlorine-ion and Carbonation resistance of the recycled aggregate concrete was investigated. Coarse aggregate was replaced with $100\%$ of the recycled aggregate and cement and fine recycled aggregate was replaced with various amount. It was shown that the concrete can obtain resistance of chlorine-ion, when fly ash replaced with up to $30\%$ of cement.

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