• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.2
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• pp.75-83
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• 2000

Recently, the quantities of waste asphalt concrete at construction sites have much increased greatly. but maintaining a filling-up and final disposal place is a difficult problem. Therefore, we are faced with a worsening environmental problem brought about present illegal measures. So, safety treatment and recycling of construction waste is a very important question in the Preservation of environmental and natural resources In this study we performed fundamental investigation to manufacture the base recycling asphalt mixture by movable asphalt recycling machine. It contained waste asphalt concrete and recycling agent and its quality was equal to virgin asphalt concrete.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2019-2024
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• 2021

For evaluating the radiological safety of dismantled concrete, the process of disposal and recycling of the radioactive concrete generated during the dismantling of Kori Unit 1 is analyzed. Four scenarios are derived based on the analysis of the concrete recycling and disposal process, and the potential exposure to the workers and public during this process are calculated. VISIPLAN and RESRAD code are used for evaluating the dosages received by the workers and public in the following four scenarios: concrete inspection, transport of concrete by the truck driver, driving on a recycled concrete road, and public living near the landfilled concrete waste. Two worker exposure scenarios in the processing of concrete and two public exposure scenarios in recycling and disposal are considered; in all the scenarios, the exposure dose does not exceed the annual dose limit for each representative.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.123-131
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• 2014

Whole amount of waste water, approximately 921.6 liter, for cleaning a ready mixed concrete truck should be used to produce concrete as a mixing water or cleaning water. Recycling water for concrete mixing contains solids, which cause decrease in slump, air and compressive strengths, so it may influence on poor concrete quality. Therefore, it has been maintained to use recycling water with less than 3 percent of solids. Since no evaluation system has been constructed to directly reflect on variability of recycling water from ready mixed concrete plants, it is necessary to develop "Automatic recycling solid measuring system" for quality controls in real time. In this research, sensors measuring waste water concentration in ultrasonic and inductance methods were developed, and automatic system using the sensors were established. The accuracy of measurement sensors developed for recycling water based on various conditions of concentration was proved, and application limits were evaluated. Also, concentration of recycling water using sensors developed from ready mixed concrete plant was measured, and curing method verified the accuracy of the sensors. Moreover, measurement sensors for recycling water in various locations were installed to evaluate the effects on measuring method and spots. The automatic measuring system for recycling water concentration, which is developed in the research, will contribute to improve concrete quality safety through reliable solids maintenance.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.561-566
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• 1999

Due to recent demolition works of aged concrete bridges and buildings, a considerable amount of waste concrete material have been reclaimed without crushing works. It is well believed that waste concrete could be used for recycling good coarse aggregate, which could contribute to partly reduce environmental pollutions due to noise and dust by demolition works, and also to solve the shortage of natural aggregate for new concrete works. This experimental study is to investigate the flexural and shear behaviour of recycling RC beams with pertinent amount of recycling coarse aggregate, such as 30%, 50% and 100% of total aggregate volume. It is concluded from the test that structural behaviour of recycled concrete is determined to have similar behaviour of normal concrete.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.530-545
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• 2023

As an alternative to conventional management options for a lot of concrete waste from decommissioning of nuclear power plants, a set of scenarios for controlled recycling of decommissioning concrete waste as engineered barriers of a radioactive waste repository was proposed, and a comprehensive safety assessment model and framework covering both pre-and post-closure phases was newly developed. The new methodology was applied to a reference vault-type repository, and the ratios of derived concentration limits to unconditional clearance levels of eighteen radionuclides for controlled recycling were provided for three sets of dose criteria (0.01, 1, and 20 mSv/y for the pre-closure and 0.01 mSv/y for the post-closure phases). It turns out that decommissioning concrete waste whose concentration is much higher than the unconditional clearance level can be recycled even when the dose criterion 0.01 mSv/y is applied. Moreover, a case study on ABWR bio-shield shows that the fraction of recyclable concrete waste increases significantly by increasing the dose criterion for the radiation worker in the pre-closure phase or the duration of storage prior to recycling. The results of this study are expected to contribute to demonstrating the feasibility of controlled recycling of a lot of decommissioning concrete waste within nuclear sectors.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.327-328
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• 2021

In the manufacturing process of ready-mixed concrete, quantity management directly affects the workability and strength of concrete. Therefore, water quantity is the most important management factor for water quality control of ready-mixed concrete. It can be said that the number of unit water in the mix design, the water quantity due to the surface water contained in the aggregate used, and the water quantity taking into account the concentration of sludge contained in the recycling water when using the recycling water are factors that affect the quantity management of ready-mixed concrete. In this study, as a stable quality control method of ready-mixed concrete, a quantity management method by aggregate surface water and a sludge concentration management method according to the use of recycling water were proposed. Thus, we tried to suggest an efficient quantity management method for stabilizing the quality of ready-mixed concrete.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2003.10a
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• pp.129-133
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• 2003

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.777-780
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• 2008

There were some attempt to reuse water with sludge combinative water for ready mixed concrete. But recycling water consist of cement, aggregate and chemical admixture. So it caused deterioration of concrete. The object of this study was to search for recycling method of the recycling water sludge as mineral admixture. This experiment dealed with the effect of $2.5{\sim}12.5$% range of the recycling sludge which can be used for admixture binder(BFS, FA, BFS+FA) on properties of activated recycling water sludge for admixture of concrete. As a result, Although the slump levels reduced and air contents increased as sludge replacement levels increased, it didn't change highly. The compression strength of concrete slightly increased with an increasing amount of recycling water sludge replacement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.2
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• pp.65-71
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• 2001

Recently the quantities of waste asphalt concrete at construction sites have increased greatly, but the maintenance and final disposal is very difficult problem. Therefore, we were faced with a worsening environmental problem brought about illegal measures. One of the most effective recycling method is cold recycling. This method will satisfy treatment and recycling of construction wastes. Also it is very important question in the preservation of environmental and natural resources. So, in this paper, we dealt cold recycling modified asphalt mixtures using emulsified asphalt to concern the effect of adding reclaimed asphalt concrete 30, 40, 50% and using SBR Latex for modified asphalt mixtures.