• Advances in concrete construction
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• v.9 no.2
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• pp.207-215
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• 2020

This paper describes the experimental studies carried out to determine the properties of fresh and hardened concrete with Recycled Plastic Waste (RPW) as a partial replacement material for fine aggregates. In the experimental study, RPW was used for replacing river sand and manufactured sand (M sand) aggregates in concrete. The replacement level of fine aggregates was ranging from 5% to 20% by volume with an increment of 5%. M40 grade of concrete with water cement ratio of 0.40 was used in this study. Two different types of RPW were used, and they are (i) un-activated RPW and (ii) activated RPW. The activated RPW was obtained by alkali activation of un-activated RPW using NaOH solution. The hardened properties of the concrete determined were dry density, compressive strength, split tensile strength, flexural strength and ultrasonic pulse velocity (UPV). The properties of the concrete with river sand, M sand, activated RPW and un-activated RPW were compared and inferences were drawn. The effect of activation using NaOH solution was investigated using FT-IR study. The micro structural examination of hardened concrete was carried out using Scanning Electron Microscopy (SEM). The test results show that the strength of concrete with activated RPW was more than that of un-activated RPW. From the results, it is evident that it is feasible to use 5% un-activated RPW and 15% activated RPW as fine aggregates for making concrete without affecting the strength properties.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.5
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• pp.31-39
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• 2007

This study was carried out to evaluation the recycled waste soils from construction site for planting soil. For this purpose, the concentrations of polluted materials and the physico-chemical properties were measured at recycled soil samples of an industrial waste treating company in the Metropolitan landfill area. The concentrations of polluted materials did not exceed to the standard critical levels of soil pollution in all analyzed items. The measures of the samples soil texture (loamy sand), bulk density (1.09~1.32g/$cm^3$), saturated hydraulic conductivity ($1.6{\times}10^{-3}{\sim}1.8{\times}10^{-3}$cm/sec), solid phase distribution (0.4~0.5$m^3/m^3$), porosity (0.5~0.6$m^3/m^3$), Ex. $K^+$ (1.0~1.2cmol/kg), Ex. $Mg^{2+}$ (0.2~0.6cmol/kg) were identified as not worse than those of conventional planting soil. But the sample soils have serious problems for planting soil such as high levels of pH (9.6~11.5), EC (0.78~1.84ds/m) and Ex. $Ca^{2+}$ (25.6~34.5cmol/kg), low level of organic matter (0.2~0.3%). It is required to improve pH, EC and Ex. $Ca^{2+}$ of sample soils. Consequently, the results suggested a high potential of recycling of the wastes soils for planting soil.

• Journal of the Korean GEO-environmental Society
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• v.6 no.2
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• pp.31-38
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• 2005

Flowable fills are self-leveling, liquid-like materials, and self-compacting to 95-100% of the maximum unit weight. Benefits of flowable fills include limited required labor, accelerated construction, ready placement at inaccessible locations, and the ability to be manually re-excavated. Applications for flowable fills include utility trenches, building excavations, underground storage tanks, abandoned sewers and utility lines, and filling underground mine shafts The objective of this study is to estimate engineering property of flowable fills made of soil mixed with recycled stylofoam and stabilizer for using geotechnical field. For this study, the uniaxial compression test, flowable test, and model tests were performed. Based on the results of the tests, the following conclusions are : fills made of soil mixed with recycled stylofoam and stabilizer can be used as flowable fills, minimum stabilizer quantity for using flowable fills ranges from 1.0($kN/m^3$) to 1.2 ($kN/m^3$).

• Composites Research
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• v.35 no.4
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• pp.242-247
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• 2022

This study has a different direction from the existing technology of applying recycled carbon fiber obtained by recycling waste CFRP to CFRP again. A study was conducted to utilize recycled carbon fiber as a raw material for manufacturing a carbon/carbon (C/C) composite material comprising carbon as a matrix. First, it was attempted to recycle a commonly used epoxy resin composite material through a thermal decomposition process. By applying the newly proposed oxidation-inert atmosphere conversion technology to the pyrolysis process, the residual carbon rate of 1~2% was improved to 19%. Through this, the possibility of manufacturing C/C composite materials utilizing epoxy resin was confirmed. However, in the case of carbon obtained by the oxidation-inert atmosphere controlled pyrolysis process, the degree of oxygen bonding is high, so further improvement studies are needed. In addition, short-fiber C/C composite material specimens were prepared through the crushing and disintegrating processes after thermal decomposition of waste CFRP, and the optimum process conditions were derived through the evaluation of mechanical properties.

• Magazine of RCR
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• v.11 no.3
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• pp.18-24
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• 2016

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.211.2-211
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• 2003

• Magazine of RCR
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• v.13 no.3
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• pp.32-38
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• 2018

• Magazine of RCR
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• v.16 no.4
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• pp.30-36
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• 2021

• Magazine of RCR
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• v.14 no.1
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• pp.10-16
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• 2019

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.4
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• pp.291-296
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• 2014

For the purpose of energy consumption and green-house gas reduction from building, new insulation materials with improved thermal property have been developed and used. Among new insulation materials, mineral hydrate which compensates for the defects of existing materials is using as a prominent insulation material. The fabrication method of mineral hydrate is similar to that of ALC for building structure but mineral hydrate is only used for insulation. The raw materials that make up of mineral hydrate are cement, lime and anhydrite. Especially anhydrite is all dependant on imports. In this study, Desulfurization Gypsum(DG), by-product of oil plant, was used for replacing for imported anhydrite and waste recycling. DG substituted all of anhydrite and a part of lime. Mineral hydrate used DG had analogous thermal and physical properties, compared to existing mineral hydrate.