• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.57-62
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• 1998

As the waste concrete is increased by demolition according to the plan of city-reconstruction and preperation of city-environment etc, the production of waste concrete in the country is being very increased every years. Because the use of recycled aggregate is low, the cases of unlawful reclamation and disuse are increased. These occur the social and economic problems. This experimental study is to investigate the fluidity, compressive strength and durability of flowing recycled aggregate concrete using the river sand and recycled coarse aggregate according to the replacement rate of fly-ash and to present the fundamental data for the using of flowing recycled aggregate concrete.

• Computers and Concrete
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• v.10 no.2
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• pp.95-104
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• 2012

This study uses recycled green building materials based on a Taiwan-made recycled mineral admixture (including fly ash, slag, glass sand and rubber powder) as replacements for fine aggregates in concrete and tests the properties of the resulting mixtures. Fine aggregate contents of 5% and 10% were replaced by waste LCD glass sand and waste tire rubber powder, respectively. According to ACI concrete-mixture design, the above materials were mixed into lightweight aggregate concrete at a constant water-to-binder ratio (W/B = 0.4). Hardening (mechanical), non-destructive and durability tests were then performed at curing ages of 7, 28, 56 and 91 days and the engineering properties were studied. The results of these experiments showed that, although they vary with the type of recycling green building material added, the slumps of these admixtures meet design requirements. Lightweight aggregate yields better hardened properties than normal-weight concrete, indicating that green building materials can be successfully applied in lightweight aggregate concrete, enabling an increase in the use of green building materials, the improved utilization of waste resources, and environmental protection. In addition to representing an important part of a "sustainable cycle of development", green building materials represent a beneficial reutilization of waste resources.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.39-40
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• 2011

This study is to analyse possibility cementitious powder from waste concrete as row material of recycled cement. From the results, we ascertained possibility as recycled cement through XRF & XRD of cementitious powder & recycled cement. As a result of the experiment, cementitious powder from waste concrete, which appeared to recovery hydration chemically at the calcining temperature of 700, suggested highly possibility as recycled cement.

• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.71-78
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• 2005

This study focuses on finding out engineering characteristics of asphalt concrete mixtures using mineral fillers with recycled waste lime, which is a by-product in the Soda Ash(Na2CO3) production course. The materials tested in this study were made with 25%, 50%, 75% and 100% of mixing ratio based on the conventional mineral filler ratio to analyze the recycle possibility of the waste lime. The asphalt concrete mixtures with recycled waste lime and hydrated lime, and conventional asphalt concrete mixtures were evaluated through their fundamental engineering properties such as Marshall stability, indirect tensile strength, resilient modulus, permanent deformation characteristics, moisture susceptibility and fatigue resistance. The results indicate that the application of recycled waste lime as mineral filler improves the permanent deformation characteristics, stiffness and fatigue endurance of asphalt concrete mixtures at the wide range of temperatures. It is also found that the mixtures with recycled waste lime show higher resistance against stripping than conventional asphalt concrete mixtures. It is concluded from various test results that the waste lime can be used as mineral fillers and especially can greatly improve resistance to permanent deformation of asphalt concrete mixtures at high temperatures.

• Advances in concrete construction
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• v.4 no.4
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• pp.263-281
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• 2016

Concrete continues to be the most consumed construction material in the world, only next to water. Due to rapid increase in construction activities, Construction and Demolition (C&D) waste constitutes a major portion of total solid waste production in the world. It is important to assess the amount of C&D waste being generated and analyse the practices needed to handle this waste from the point of waste utilization, management and disposal addressing the sustainability aspects. The depleting natural resources in the current scenario warrants research to examine viable alternative means, modes and methods for sustainable construction. This study reports processing Recycled Coarse Aggregates (RCA) using a rod mill, for the first time. Parameters such as amount of C&D waste for processing, nature of charge and duration of processing time have been optimized for obtaining good quality RCA. Performance of RCA based concrete and performance enhancement techniques of 50% RCA based concrete are discussed in this paper.

• International Journal of Highway Engineering
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• v.16 no.5
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• pp.39-47
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• 2014

PURPOSES : This study aimed to analyze economic effect of recycled aggregate production on job-site airport pavement. METHODS : The validation of site recycling for waste concrete as economic efficiency is analyzed through the case study of site recycling at an O airport pavement construction. The break-even point for the cost of site recycling was estimated according to two different waste concrete processing methods such as job-site recycling and processing on commission (or plant). RESULTS : Job-site recycling cost decreases as the use rate of job-site recycled concrete aggregate increases, or the amount of concrete waste increases, but transporting distance decreases. It was shown in an O airport case that as the use rate of job-site recycled concrete aggregate exceeds 61.4 %, the job-site recycling cost is cheaper than the processing cost on commission. CONCLUSIONS : The results of this study can utilize basic data of feasibility for site recycling of waste concrete on airport pavement construction.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.571-575
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• 2001

To examine the grinding effect through preheating of waste concrete as a way of retrieving coarse aggregates from waste concrete, the removal rates of cement mortar and paste of both recycled aggregates and heated and grinded ones were investigated. As the preheating temperature increased, the removal rate of cement mortar from waste concrete was raised, and this kind of removal hardly affected the abrasion rate and specific gravity of aggregates. On the other hand, when it was treated over 40$0^{\circ}C$ of preheating temperature, the absorptance was reduced to less than 2.17, and cement mortar was effectively separated from waste concrete. It could meet the Korean Standards on recycled aggregates for concrete, and it is expected to expand the scope of utilization by making it possible to retrieve the aggregates which have the properties close to natural aggregates.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.53-56
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• 2007

Recently, waste concrete emission has been increased by acceleration of urban development and the rapid growth of redevelopment projects, so recycling of waste concrete is actively progressed, But the usage is limited to a lower value added such as the roadbed material etc. To produce the high quality recycled aggregate, breaking and washing process is added to the existing process and inevitably increases the occurrence of particle, because old mortal is included in the recycled aggregate. Therefore, this study purpose is analysis the properties of lightweight foamed concrete made by waste concrete sludge which is the by-product from produce the recycled aggregate. In result, possibility of manufacture of lightweight foamed concrete which gives equal performance compared with ALC was detect(scope of density : $0.5{\sim}0.6$, scope of compressive strength : $3.5{\sim}4.0MPa$). And scope of porosity is as follow ; total porosity : $27{\sim}30%$, open porosity : $1{\sim}5%$

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.568-571
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• 2004

This research estimated the physical. mechanical characteristic and the character of sound absorption according to target void ratio of porous concrete and the mixing ratio of recycled aggregate for the valid utilization of recycled aggregate using waste concrete and sound reduction out of a road, a railway, a residential street, and a downtown area. As a result of the test, compressive strength tended to be a radical strength fall when target void ratio was $25\%$ and contents of recycled aggregate exceeded over $50\%$. Also, the character of sound absorption of porous concrete which used recycled aggregate using waste concrete was the most excellent when target void ratio was $25\%$, and the influence by contents of recycled aggregate was trivial. Therefore, when the strength and the character of sound absorption of porous concrete are considered, it is proved valid that proper target void ratio was $25\%$ and contents of recycled aggregate using waste concrete was $50\%$ or so.

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.13-20
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• 1999

Recently, the study for practical construction application no recycled aggregate concrete is actively being proceeded, on the purpose of technical development for recycling on the construction waste concrete occurred at the time of destruction of building construction by the rapid increase of building wastes and exhaustion of natural aggregates. But, the durability of investigation with all sorts of fluidity and engineering property for application recycled aggregate concrete to practical construction must be done at the same time. Especially, because of the real condition for chemical attack of concrete construction by the acid rain, acidification of soil, deepening of air pollution and dirty water etc. being come to the fore a serious problem, the study on the chemical soundness of concrete durability must be accompanied. This study is composed as: I series: Analysis for chemical soundness of aggregates. II series: Analysis for chemical soundness of natural and recycled aggregate concrete against $Na_2$$SO_4$ solution in drying and wet curing condition ($at20~80^{\circ}C$).