• 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.

• Resources Recycling
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• v.10 no.2
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• pp.41-49
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• 2001

In this study, the properties of cement mortar and concrete using ceramic wastes as fine aggregates and coarse aggregates are considered experimentally. Flow value of mortar using ceramic waste as fine aggregates is increased more or less, and the com- pressive strength of mortar using ceramic wastes as fine aggregates is increased with elapsed age. The slump value of concrete using ceramic wastes fine aggregates and coarse aggregates is somewhat decreased. The compressive strength of concrete using ceramic wastes as fine aggregates and coarse aggregates is lower than that of OPC concrete in early age, but has gradually increased in long ages.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.67-74
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• 2009

Nowadays, recycling of recycled aggregates from the waste concrete is seriously demanded for the protection of environment and the shortage of aggregates owing to the large scale construction project. In this study, for the development of polymer composite recycling recycled aggregates from the waste concrete, twenty five specimens of the polymer composite were prepared with the five levels of replacement ratios of recycled aggregates (0, 25, 50, 75, 100%) and polymer-cement ratios (0,5, 10, 15, 20%), respectively. For the evaluation of the performance of polymer composite specimens, various physical properties such as compressive and flexural strengths, water absorption, hot water resistance, total pore volume and porosity were investigated. As a result, physical properties of polymer composite were remarkably improved with an increase of polymer cement ratios, but greatly decreased with the replacement ratios of recycled aggregates.

• Journal of Powder Materials
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• v.13 no.2 s.55
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• pp.102-107
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• 2006

Recycling industrial wastes such as fly ash from a coal burning heat power plant and shell from an oyster farming were investigated to prevent environment contamination as well as to enhance the value of recycling materials. In this study, the lightweight aggregates and the red bricks were fabricated from fly ashes with other inorganic materials and wastes. The starting materials of the lightweight aggregate were fly ash powder and water glass, and the compacts of these materials were heat treated at $1100^{\circ}C$. The fabricated lightweight aggregates had low bulk density, $0.9-1.2\;g/cm^3$, hence floated on the water and had the strength of 7.0-11.0 MPa and the modulus of 2900-3300 MPa which indicates it has enough strength as the aggregate. Another type of the light weight aggregate was prepared from fly ashes, shell powders and clays. The bulk density, porosity, and compressive strength of these aggregates were $1.19-1.34\;g/cm^3,\;18.3{\sim}56.1%$ and 5-12 MPa, respectively. The addition of a small amount of fly ash powder prevented hydration of the light weight aggregates. The red brick was also fabricated from the fly ash containing materials. It is suitable for the brick facing of a building as it has moderate strength and low water absorption rate.

• Resources Recycling
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• v.23 no.2
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• pp.90-97
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• 2014

The artificial dry silica used as dry aggregates in domestic is collected increasing every year. It is required drying process for the production of dry aggregates, therefore, it is main culprit of the cost up of aggregates and air pollution by using fossil fuel for the solution, it is developed alternative aggregates for the replacement of dry aggregates very ungently. In this article, the patents and papers for the recycling technology on the high-efficiency rapid cooling method of ladle furnace slag were collected and analyzed. The open patents of USA (US), European Union (EP), Japan (JP), and Korea (KR) and SCI journals from 1977 to 2013 were investigated. The patents and journals were collected using key-words and filtered by the definition of the technology. The patents and journals were analyzed by the years, countries, companies, and technologies and the technical trends were discussed in this paper.

• Resources Recycling
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• v.16 no.5
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• pp.13-18
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• 2007

The recycled aggregates produced from waste concrete by crushing and granularity adjusting processes only can't be used for structural aggregates because they display low density and high abrasion rate by including lots of mortar and cement paste. However, the recycled aggregates include a lot of aggregates for concrete. Using the heavy medium separation method that is one of the specific gravity separation methods, about 45% of the waste concrete could be converted to the recycled aggregates.

• 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.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.269-274
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• 2002

Recently, Recycling aggregates could be gained from the reconstruction works using recycle process and the study and research of recycle concretes developed concrete application methods. It could put some outcome of studies to practical use for concrete products. The methods of crushing waste concrete are going diverse. In this study, the fundamental experiments and recycling application is investigated and analyzed with use of recycling aggregate which made of mechanical crush and underwater electrical impact crush, and the difference between underwater electrical impact crush, mechanical crush and natural aggregates is studied.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.693-698
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• 2002

The production accounts of domestic by-product is increased after 1990's. It is worried about the life reduction of dump land, as dump land's capacity have reached to limitation and the amount of construction industrial wastes is going higher. Recently, recycling aggregates could be gained from the reconstruction works using recycle process. And the study and research of recycle concretes developed concrete application methods. It could put some outcome of studies to practical use for concrete products. The methods of crushing waste concrete are going diverse. In this study, the fundamental experiments and recycling application is investigated and analyzed with use of recycling aggregate which made of mechanical crush and underwater electrical impact crush. and the difference between underwater electrical impact crush, mechanical crush and natural aggregates is studied.