• Title/Summary/Keyword: Recycled aggregates

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A Study on Rational Evaluation of Recycled Aggregates Extracted from Demolished Concrete (폐콘크리트로부터 재생된 골재의 합리적 평가에 관한 연구)

  • 송하원;변근주;하주형
    • Journal of the Korea Concrete Institute
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    • v.12 no.5
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    • pp.3-12
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    • 2000
  • Recently, the amount of disposed construction materials like demolished concrete is growing fast and the shortage of natural concrete aggregates is becoming serious. Therefore, recycling of aggregates extracted from the demolished concrete is getting important and use of the recycled aggregates for concrete has been seriously considered. However, the use of the recycled aggregates even for low performance concretes is very limited because there are few rational standard evaluation criteria for recycled aggregates which should be different from that for natural aggregates. In this study, rational evaluation criteria for the recycled aggregates are proposed for their use as concrete aggregates. The study also shows that the performance for both the recycled aggregates and the recycled concrete manufactured with the recycled aggregates can be evaluated effectively according to water absorption ratio of recycled aggregates.

An Experimental Study on the Strength Characteristic of Recycled Concrete by Curing Method (재생콘크리트의 양생 방법별 강도 특성에 관한 실험적 연구)

  • Choi Maeng Ki;Park Hee Gon;Kim Kwang Ki;Jung Kwang Sic;Jung Kuen Ho;Jung Sang Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.11a
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    • pp.723-726
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    • 2005
  • As the importance of recycled materials is being emphasized more in the Korean construction market, the production quality has been improved to a significantly high level. Compared to the high quality, however, there are used very limitedly. Among recycled construction materials, recycled aggregates produced through the retreatment of waste concrete are drawing attention because of lack of natural aggregate and heightened consciousness of resource saving and environmental protection and, as a consequence, they are close to natural aggregates in terms of production technology and quality. Despite the high quality and productivity, however,. the utilization of recycled aggregates is very low. Thus, in order to maximize the utility of recycled aggregates, the present study examined the usability of recycled aggregates using both recycled coarse aggregates and recycled fine aggregates together and derived optimal quantity and mixture ratio in the combined use of the two types of recycled aggregate.

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Strength Characteristics of Unsaturated Polyester Resin Mortar using Recycled Fine Aggregates

  • Kim, Wha-Jung;Choi, Young-Jun;Jun, Joo-Ho;Kim, Yong-Bae
    • KCI Concrete Journal
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    • v.11 no.3
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    • pp.89-97
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    • 1999
  • The purpose of this research is to investigate the utilization of recycled fine aggregates as a material to apply to a building finished walls or as a decorating material in combination with a polymer. The strengths of two resin mortars using recycled fine aggregates and natural fine aggregates was made. In order to improve the workability and the strength of the resin mortar with recycled fine aggregates, partial replacement of recycled fine aggregates with natural ones was made with the application of various type of fillers. The results, it show that the compressive strength and flexural strength of resin mortar using the recycled fine aggregates were about 70% to 100% of those of resin mortar using natural fine aggregates. It was enough to assure the utilization of the recycled fine aggregates as a material for the production of resin mortar. From the result of partial replacement of recycled fine aggregates with natural ones, the compressive strength was Increased from 5% to 15% and the flexural strength was much as 5% to 20% as a result of 70% substitution It was also found that the use of garnet powder shows a similar tendency in the compressive strength and slag powder does in the flexural strength and tensile strength.

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Evaluation of the geogrid-various sustainable geomaterials interaction by direct shear tests

  • Bahadir Ok;Huseyin Colakoglu;Umud Dagli
    • Geomechanics and Engineering
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    • v.34 no.2
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    • pp.173-186
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    • 2023
  • In order to prevent environmental pollution, initiatives to increase the sustainability of resources are supported by society. However, the performance of recycled materials does not generally match that of natural materials. This study looks into the use of geogrid to improve various types of recycled aggregates. For this purpose, five different recycled aggregates were created by recycling wastes from the construction industry. Besides, direct shear tests (DS tests) were carried out on these recycled aggregates to determine their shear strengths. Following that, a triaxial geogrid was placed in the recycled aggregates to provide reinforcement, and the DS tests were conducted on the reinforced recycled aggregates. The results of the tests were also compared to those of tests performed on natural aggregates (NA). In conclusion, it was found that the recycled aggregates have lower shear strengths than the NA. Nonetheless, when reinforced with geogrid, the shear strength of the recycled concrete aggregates (RCA) and construction and demolition wastes (CDW) exceeded that of the NA. Furthermore, the geogrid reinforcement increased the shear strength of the recycled crushed bricks (CB), though not to the level of the NA.

A Study on the Properties of Recycled Aggregate Concrete applied to Mock-up (Mock-up에 적용한 재생골재콘크리트의 특성 연구)

  • Shim Jong-Woo;Lee Sea-Hyun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.93-96
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    • 2005
  • In this study, Mock-up was manufactured using recycled aggregate concrete and then analyzed with respect to physical properties. Finally, the applicability of recycled aggregates as constructional aggregates was reviewed by practically putting recycled aggregates concrete into construction. Right after mixing, the slump of recycled-aggregates concrete showed decreased slump as time goes by because the surface mortar of recycled aggregates absorbed the mix water with time passing. The air contents of recycled-aggregates concrete overall increase a little due to the effect of surface mortar of the aggregates. For strengths, the strengths of recycled aggregate concrete tended to decrease from the proportion of 30$\%$ to 100$\%$.

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Experimental Study on Mechanical Properties and Deformation Behavior of Concrete with Recycled Aggregates and Steel Fiber (순환골재 및 강섬유를 혼입한 콘크리트의 역학적 특성 및 변형 거동에 관한 실험적 연구)

  • Lee, Hyun-Ho;Lee, Tae-Wang
    • Journal of the Korea Concrete Institute
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    • v.28 no.3
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    • pp.357-363
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    • 2016
  • To solve the exhaustion problem of natural aggregate which were create the high value in construction and environmental industry, recycled aggregates have considerable benefits than other materials. However, even though many researches have been conducted with recycled aggregates, building structures with recycled aggregated are rarely constructed because it has lower quality than natural aggregates have. In this study, mechanical and strain properties of recycled aggregates concrete containing steel fibers have been reviewed in order to complement performance of recycled aggregates concrete. As results, recycled aggregates concrete showed lower compressive strength and elastic modulus than plain concrete. But, recycled aggregates concrete containing steel fibers showed equivalent performance with plain concrete. In review of drying shrinkage and creep coefficient, recycled aggregates concrete containing steel fibers showed similar behavior with plain concrete in the range of 0.5 Vol.% fiber content rate by internal restraint effect, moisture transport restraint effect and strength enhancement effect of steel fiber. Therefore, it is considered that mixing steel fibers with concrete is the effective method as a active application plan for recycled aggregates.

Thermal Resistivity Measurement of Recycled Aggregates and Comparison with Conventional Prediction Model (송배전관로 되메움용 순환골재의 열저항 측정 및 기존 열저항 예측 모델과의 비교)

  • Wi, Jihae;Hong, Sungyun;Choi, Hangseok
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.11a
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    • pp.199.1-199.1
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    • 2010
  • Use of recycled aggregates that are constituents of concrete or asphalt-based structures has become popular because the recycling is an eco-friendly way to overcome the depletion of natural aggregates. In order to adopt the recycled aggregates for backfilling a power transmission pipeline trench, their thermal resistivity should be low enough to prevent thermal runaway in the transmission system. In this study, a series of laboratory tests with QTM-500 and KD2 Pro was performed to measure the thermal resistivity of recycled aggregates prepared from various sources. Relationships between the thermal resistivity of recycled aggregates and the water content have been obtained with consideration of compaction effort. Similar to natural soils, the thermal resistivity of the recycled aggregates decreases with increasing the water content. In addition, this study compared the experimental data with conventional prediction models for the thermal resistivity in the literature, which suggests the availability of the recycled aggregates as backfill material substituting for natural aggregates when backfilling the power transmission pipeline trench.

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Rheological, physico-mechanical and durability properties of multi-recycled concrete

  • Rahmani, Abdessamed Azzaz;Chemrouk, Mohamed;Ammar-Boudjelal, Amina
    • Advances in concrete construction
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    • v.9 no.1
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    • pp.9-22
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    • 2020
  • The present work looks at the possibilities of recycling more than once demolished concrete as coarse aggregates, to produce new concrete. Different concrete mixes were made with substitutions of 50%, 75% and 100% of recycled concrete aggregates respectively as coarse aggregates. The physico-mechanical characterization tests carried out on the recycled concrete aggregates revealed that they are suitable for use in obtaining a structural concrete. The resulting concrete materials had rheological parameters, compressive strengths and tensile strengths very slightly lower than those of the original concrete even when 100% of two cycles recycled concrete aggregates were used. The durability of the recycled aggregates concrete was assessed through water permeability, water absorption and chemical attacks. The obtained concretes were thought fit for use as structural materials. A linear regression was developed between the strength of the material and the number of cycles of concrete recycling to anticipate the strength of the recycled aggregates concrete. From the results, it appear clear that recycling demolished concrete represents a valuable resource for aggregates supply to the concrete industry and a the same time plays a key role in meeting the challenge for a sustainable development.

Experimental Study on the Properties of Recycled Concrete using Recycled Coarse Aggregates and Steel Slag Fine Aggregates (재생 굵은골재와 제강슬래그 잔골재를 사용한 재생 콘크리트의 특성에 관한 실험적 연구)

  • Lee, Jaesung;Na, Okpin
    • Resources Recycling
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    • v.24 no.5
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    • pp.63-71
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    • 2015
  • The purpose of this study is to investigate the optimum replacement rate and material properties of eco-friendly recycled concrete using recycled coarse aggregates and rapid-chilled steel slag fine aggregates. The replacement rate of recycled coarse aggregates was increased from 30% to 50% of total volume of coarse aggregates and the rapid-chilled steel slag aggregates were substituted for 10% to 50% of total volume of fine aggregates. As a result, the increment of recycled coarse aggregates in concrete caused the reduction of the compressive strength. On the other hand, as increasing the replacement ratio of rapid chilled steel slag aggregates, the compressive strength was enhanced. Furthermore, the optimum use of rapid chilled steel slag aggregates was suggested up to 20~30% of fine aggregates and the use of it could be helpful to expand the replacement rate of recycled aggregates.

Mechanical, rheological, and durability analysis of self-consolidating concretes containing recycled aggregates

  • Hiwa Mollaei;Taleb Moradi Shaghaghi;Hasan Afshin;Reza Saleh Ahari;Seyed Saeed Mirrezaei
    • Structural Engineering and Mechanics
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    • v.88 no.2
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    • pp.141-157
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    • 2023
  • In the present paper, the effect of recycled aggregates on the rheological and mechanical properties of self-consolidating concrete is investigated experimentally and numerically. Hence, the specimen with two types of recycled aggregates, i.e., known and unknown resistance origins, are utilized for the studied specimens. The experiments in this study are designed using the Box-Behnken method, which is one of the response surface methods. Input variables in mixtures include silica fume in the range of 5-15% as a percentage substitute for cement weight and recycled coarse and fine aggregates in the range of 0-50% for both series of recycled materials as a substitute for natural materials. The studied responses are slump flow, V funnel, compressive strength, tensile strength, and durability. The results indicate that the increase in the amount of recycled aggregates reduces the rheological and mechanical properties of the mixtures, while silica fume effectively improves the mechanical properties. In addition, the results demonstrate that the fine recycled aggregates affect the total response of the concrete significantly. The results of tensile and compressive strengths indicate that the mixtures including 50% recycled materials with known resistance origin demonstrate better responses up to 8 and 10% compared to the materials with unknown resistance origins, respectively. Recycled materials with a specific resistance origin also show better results than recycled materials with an unknown resistance origin. Durability test results represent those concretes containing recycled coarse aggregates have lower strength compared to recycled fine aggregates. Also, a series of mathematical relationships for all the responses are presented using variance analysis to predict mixtures' rheological and mechanical properties.