• Resources Recycling
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• v.15 no.2 s.70
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• pp.24-31
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• 2006

The duality of recycled fine aggregate (RS) which was produced at the waste concrete crushing was investigated. The compressive strength, flexural strength and absorption of mortar utilized with RS were examined. It was evaluated on the application of RS as precast concrete aggregate. The density and absorption of RS were $2.31g/cm^3$ and 8.07% respectively, the quality of RS was satisfied with the criterion of KS F 2573 type 2. The maximum 28days compressive strength of mortar mixed with blended cement MRS1, MRS2 and MRS3 were developed with 15.8, 27.4 and 48.7MPa respectively, in condition to curing temperature $40^{\circ}C$ and water-cement ratio 37.5%. When blended cement MRS1 and MRS2 were used, the maximum flexural strength of mortar was developed at curing temperature $40^{\circ}C$ and water-cement ratio 35.0%. When blended cement MRS3 was used, the maximum flexural strength of mortar was developed at curing temperature $40^{\circ}C$ and water-cement ratio 37.5%. The absorption of mortar mixed with blended cement MRS1, MRS2 and MRS3 were indicated the range of $8.3{\sim}7.3%,\;6.5{\sim}8.5%$ and $3.5{\sim}6%$ respectively. Therefore, when the ratio of blended cement and RS is appropriately centre]led, it would be expected that MRS1, MRS2 and MRS3 will be able to apply the variable low strength, medium strength and high strength precaste concrete.

• Journal of the Korea Institute of Building Construction
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• v.3 no.1
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• pp.147-154
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• 2003

Recently, the amount of the construction and demolition wastes has rapidly increased due to increasing construction projects. In the past, most of the construction and demolition wastes were buried in the ground of thrown away. Illegally, without any treatment, so various harmful environmental pollution problems were occurred. In this study, the domestic data on the amount of the construction and demolition wastes and the disposal methods were collection and analysed. Specially, the recycling and management systems of the construction and asphalt concrete wastes were studied. A new technology and necessary policy for recycling were suggested. In general, the industrial wastes were produced in the particular place, and the amount and the characteristics of the wastes able to be estimated by the studies on the treatment technology. And the investment of the facilities for the industrial wastes have been made continuously. But little attention has been relatively given to the treatment technology. And system for the construction and demolition wastes for the political support and facilitation on the proper treatment and the recycling, the necessary of information exchange system and the manifest system for treatment of waste on commission were recommended, and also devised methods to develope and support the recycling industry. In the future, the subject of study is going to carry out analysis of economic and market in making products.

• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.105-112
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• 2005

This is to find out that cement mortar mixed with waste tie particle can be applied for recycling it and enhanced to have shock absorption capacity. Therefore, architectural material specification and its related references for the disposal of it are based on for the study. Test has been performed with procedure, based on the Korea Standard insulation mortar and Compressive Strength Test has been done at K remicon factory approved by Korea Government in Korea, in order to decrease any possible error in mixing procedure. Test molds far insulation capacity and cohesive strength have been delivered to the expert agency for having more exact results. The result from the above test shows that waste tyre mixed with cement mortar has almost equal to the common concrete. This means that the recycling of the waste t)re will be demanded more and more in case of having continued development for this recycling area. And also waste t)to-using construction material can be more applied for construction area than existing material. Thus, this recycling method can be very usefully applied for solving environmental problem and for establishing economic aspect.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.481-487
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• 2009

On the paved track, the railway ballast is used as aggregate for the filling layer using the pre-packed concrete method. The condition of ballast as the paved track aggregate ensure that the compressive strength, particle distribution size for the pouring and surface clearance to increase the adhesive strength with mortar. It is profitable to recycle the existing railway ballast as a economical supply. In order to increase recycling characteristic, it is necessary to apply the similar criterion which does not exceed the conventional railway ballast criterion. Consequently, this paper was to investigate physical characteristics of existing ballast, particle size distribution, compressive and flexural strength, bearing capacity and filling capacity to prepare the aggregate's recycling. As a result, optimized aggregate criterion is suggested.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.57-63
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• 2013

PURPOSES: This study is to investigate the Hot In-Place recycling asphalt mixture in Korea using field produced materials. METHODS: Hot In-Place reclaimed asphalt mixture was investigated to evaluate the mixture properties based on various test results such as Marshall Test, Indirect Tensile Test, TSR, and Wheel Tracking Test. These test values were compared with domestic standard specification. RESULTS: The result of the laboratory experiment indicates that the Hot In-Place Reclaimed(HIR) asphalt mixture produced at the field constrution site was satisfied all of the test criteria such as Indirect tensile test, Marshall and TSR test, and wheel tracking test. During the test, the research team found that current HIR system is required an extention of mixing time to improve quality and to reduce variation of sample to sample. Although the current HIR mixture was passed the test criteria, there is a potential capability to enhance the mixture properties as extend mixting time. CONCLUSIONS: Based on these laboratory test results, It would be concluded that domestic HIR mixture's properties were satisfied all standard specification related with evaluation of recycling asphalt mixtures. Based on this case study result, there is a chance to save construction cost and increase the usage of reclaimed asphalt concrete in the future.

• KIEAE Journal
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• v.8 no.5
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• pp.61-68
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• 2008

For the recycling of the resources and the preservation of the environment, this study's purpose is to measure flexural behavior of the reinforced concrete beams with the major variables like concrete strength, replacement ratio of the recycled aggregate and the waste foundry sand and the tension reinforcement ratio and to present the data of the recycled aggregate used for the structure design. The experiment on the flexural behavior resulted in the followings. The ultimate strength of recycled R/C beam was manipulated proportionate to the tension reinforcement ratio, however the strength instantly decreased after passing the ultimate load due to the destroyed concrete of the compression side. The deflection at the maximum load varied from the tension reinforcement ratio by 5.5 times. The test specimen with the tension reinforcement ratio less than $0.5{\rho}b$ showed constant curve without change in the load from the yield to the ultimate load in contrast to the distinctive plastic region where the displacement was rising. Although the strain of main tension steel with the reinforcement ratio indicate different, the design of recycled concrete member can be applied for current design code for reinforced concrete structure as the ratio of tension reinforcement district the under the reinforcement ration in a balanced strain condition.

• 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.

• Advances in concrete construction
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• v.5 no.6
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• pp.563-573
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• 2017

Transparency, excellent toughness, thermal stability and a very good dimensional stability make Polycarbonate (PC) one of the most widely used engineering thermoplastics. Polycarbonate market include electronics, automotive, construction, optical media and packaging. One alternative for reducing the environmental pollution caused by polycarbonate from electronic waste (e-waste), is to use it in cement concretes. In this work, physical and chemical characterization of recycled polycarbonate from electronic waste was made, through the analysis by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM). Then cement concrete was made with Portland cement, sand, gravel, water, and this recycled polycarbonate. Specimens without polycarbonate were produced for comparison purposes. The effect of the particle sizes and concentrations of recycled polycarbonate within the concrete, on the compressive strength and density was studied. Results show that compressive strength values and equilibrium density of concrete depend on the polycarbonate particle sizes and its concentrations; particularly the highest compressive strength values were 20% higher than that for concrete without polycarbonate particles. Moreover, morphological, structural and crystallinity characteristics of recycled polycarbonate, are suitable for to be mixed into concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.26-32
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• 2020

Concrete recycling is becoming mandatory rather selective due to depletion of constructional materials and increase of concrete waste. Studies on recycling concrete are conducted in various point of view for long time. However, standard or guideline of many countries for the application of recycled aggregate concrete(RAC) has restrictions such as low replacement rate of coarse aggregate and no fine aggregate allowed due to inferior material properties of recycled aggregate. This study intends to figure out the feasibility of casting natural aggregate concrete(NAC) and RAC separately in a structural member. In making RAC, replacement rate of coarse aggregate was 50, 100% in RAC and treatment of interface of two concretes is introduced. RAC treatment of recycled aggregate or inclusion of additives was not done as it can increase embodied energy of concrete work. Double-shear test with uniformly distributed loading was adopted to evaluate shear strength at the interface of two concretes. After curing it was hard to distinguish interface of two concretes. Experimental result revealed that specimen with higher replacement rate showed higher shear-to-compressive strength ratio, which is possibly attributed to coarse aggregate size and roughness of sheared section. Further study on the effect of various parameters is required and subsequent research activity is on-going.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.359-365
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• 2017

This study examined concrete characteristics depending on the replacement ratio of recycled fine aggregates, which suits the KS F 2573 concrete recycled aggregate standard. As physical properties, slump, air content, changes in the elapse of time and compressive strength were studied in order to provide basic data for activation of recycled fine aggregate recycling. As a result of experimenting recycled fine aggregate concrete, the increase in the replacement ratio of recycled aggregates led to the increase in slump and air content. Also, when the replacement ratio of recycled fine aggregates was 30%, it was judged that there was no problem with constructability. When the replacement ratio was 30%, recycled fine aggregate concrete had a similar tendency to natural aggregate concrete at a compressive strength of 24MPa. When the replacement ratio was 30%, at a target strength of 24MPa, recycled fine aggregate concrete had the same physical characteristics as natural aggregate concrete. This means that a replacement ratio of 30% is appropriate for replacement of recycled fine aggregates. In future, there will be a need to improve the quality of recycled fine aggregates for activating the use of recycled fine aggregates and further research will have to evaluate physical properties of recycled fine aggregate concrete using improved recycled fine aggregates.