• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.46-51
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• 2014

Increasing of waste FRP (fiber reinforced plastics) has caused environmental problems. Recently, the technology of making fibers from waste FRP, which can be used to reinforce the concrete, was developed and the reinforced concretes were tested to study the structural performance. The purpose of this study is to investigate the effect of the powder, obtained together with F-fiber from the waste FRP, on the compressive strength and the fire resistance performance as in the high strength concrete. Strength tests show that the use of recycled FRP powder does not reduce the compressive strength of high strength concrete if the volume fraction of FRP powder is less than 0.7%. Electric furnace test results also show that the use of recycled FRP powder may increase the fire resistance performance of high strength concrete significantly.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.39-55
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• 1999

Geotextile composites to improve the weather ability were composed of recycled polyester geotextile with carbon black as ultraviolet stabilizer and polypropylene geotextile by needle-punching method, and evaluated physical properties, ultraviolet resistance and chemical stability. Retention ratio of tensile properties of non woven polypropylene geotextiles were decreased about 50% by the exposed condition with ultraviolet but those of geotextile composites were slightly decreased than polypropylene geotextiles. Geotextile composites which have larger weights of polyester geotextile were more stable against ultraviolet. For chemical stability, the changes of tensile properties of geotextile composites were in the range of -20~＋10% at the various chemical conditions.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.727-736
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• 2010

This paper describes results of an preliminary study to produce strain hardening cement-based composites (SHCCs)with consideration of sustainability for infrastructure applications. The aims of this study are to evaluate the influence of recycled materials on the mechanical characteristics of SHCCs, such as compressive, four-point bending, and direct tensile behaviors, and to give basic data for constitutive model for analyzing and designing infra structures with SHCCs. In this study, silica sand, cement, and PVA fibers, were partially replaced with recycled sand, fly-ash, and FET fibers in the mixture of SHCCs, respectively. Test results indicated that fly-ash could improve both bending and direct tensile performance of SHCCs due to increasing chemical bond strength at the interface between PVA fibers and cement matrices. However, SHCCs replaced with PET fibers showed much lower performance in bending and direct tensile tests due to originally low mechanical properties of own fibers, although compressive behavior is similar to PVA2.0 specimen. Also, it was noted that the recycled sand would increase elastic modulus of SHCCs due to larger grain size compared to silica sand. Based on pre-set target value to maintain the performance of SHCCs, it was concluded that the replacement ratio below 20% of fly-ash or below 50% of recycled sands would be desirable for creating sustainable SHCCs.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.234-239
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• 2023

Waste from the food is a challenge to the environment all over the globe, hence there is need to be recycled. There is a great deal of renewable energy potential in the biomass of vegetables and fruits, which can be used to generate power and steam, as well as fuel for human consumption and laboratory solvents. To maintain the nutritional, antioxidative, and functional qualities of sapota fruit, wine was made by fermenting it with wine yeast (Saccharomyces cerevisiae). The wine's approximate composition was as follows: total soluble solids, 2.38°Brix; total sugar, 3.8 g/100 ml tartaric acidity (TA), 1.29 g tartaric acidity total phenolics, 0.21 g/100 mL; pH, 3.02; acid/100 mL; pH, 3.02; total phenolics, 0.21 g/100 mL; 22 g/100 ml -carotene; 1.78 g/100 ml ascorbic acid mg/100 ml; 0.64 mg/100 ml lactic acid; and The ethanol percentage is 8.23% (v/v). The sapota wine was delicious. A DPPH-scavenging 2, 2-diphenyl-1picryl hydroxyl (DPPH) at a dosage of 250 g/ml, the activity was 46%. Infrared alcohols, phenethylamines, and other compounds were discovered via spectroscopy.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.53-59
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• 2013

Since 1990s, the major recycling methods for mechanical recycling of FRP(Fiber Reinforced Plastics)boats has involved shredding and grinding of the scrap FRP in a new recycled product. But still it leads to secondary problem such as air pollution, unacceptable shredding noise level and few limited applications. This study is to propose a newly advanced method which is more efficient and environment friendly waste FRP regenerating system. As extracting FRP layer and making the recycled fiber for recycled-fiber reinforced concrete(RFRC) from waste FRP, the recycling process has some merits in a sense of the recycling energy and the environmental effects. In this study, for those tasks, spectro-chemical differentiation method and coloring water-soluble dye treatment makes the roving layer more distinguishable photophysically. Also that has remarkably reduced safety hazards and energy. Using the mechanical properties of polymers and composite, FRP with the orthotropic and laminated plastic structure has been easily separated in the new extracting system. Also the new method has introduced five kind of separating manuals for the some different compositions of FRP boats. The roving fiber of laminated glass-fiber layer is as good as the polyvinyl fiber which is cost-high commercial fiber to increasing strength of concrete products. The early study has shown the effectiveness of laminated glass-fiber layer which also is chemical-resistant due to the resin coating. These results imply that more efficient and environment friendly recycled glass fiber can be better applied to the fiber reinforced concrete(FRC) substitute and this study also has shown wide concrete applications with RFRC from the waste FRP boat.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.82-89
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• 2009

According to the great city development and the rapid growth of redevelopment project, waste concrete emission has been increased. Waste concrete powder is one of the by-product originated from the recycling of the waste concrete. The more making high quality recycled aggregate to use aggregate for concrete, the more waste concrete powder is producted relatively. Therefore, to realize the total recycling of waste concrete, development of recycling technology for waste concrete powder need very much. This technical note present the discharged process and the various properties of waste concrete powder. As the results, on the average, the maximum particle-size of waste concrete powder is less than $600{\mu}m$, and oven-dry density is less than $2.5g/cm^3$. And waste concrete powder contains more than 50% of $SiO_2$, 30% of CaO and 10% of $Al_2O_3$. Thus qualities of waste concrete powder is lower than those of high quality raw material for concrete. However, if it is processed by grading to the purpose, it will be used as resource of raw materials for construction field.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.2
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• pp.81-88
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• 2011

This study ascertained the possibility of use of sulfur abstracted from waste sulfur as a construction material through modification process and manufacturing high efficiency modification sulfur with superior quality on dispersibility and hydrophilic in normal temperature. Mechanic, behavior and chemical durability of mortar with added modification sulfur. The results of the study are as follows. The fluidity of mortar mixed with modification sulfur and compressive strength decreased as ratio of mixing of them increases. Flexural, tensile and bond strength of the mortar are also improved and shrinkage of it increases. Especially chemical durability of the mortar showed excellent resistance with the increase of ratio of mixing. Therefore this research has confirmed the modification sulfur can be used as a addmixture for cement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.68-75
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• 2017

The study investigates the effects of the content and using method of chemical admixtures such as superplasticizer and viscosity modifying admixture on the fluidity, bleeding ratio, volumetric change and compressive strength of the grout in order to provide basic data for the development of high-quality grout for prestressed concrete. It appeared that the combination of superplasticizer and viscosity modifying admixture decreased the fluidity of grout with small content of superplasticizer. On the contrary, Grout used more than 0.1% of superplasticizer appeared to have significant effect on the improvement of the fluidity. On the other hand, bleeding of grout reduced according to increasing the content of viscosity modifying admixture. Superplasticizer with less than 0.05% had practically no effect on the reduction of bleeding, whereas superplasticizer with more than 0.1% appear to have significant effect on the reduction of bleeding. Also the combination of superplasticizer with 0.15% and viscosity modifying admixture with 0.15% resulted in satisfactory fluidity accompanied with fair reduction of bleeding and shrinkage of the grout.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2009.04a
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• pp.23-28
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• 2009

The purpose of this study was to improve not only wet-end performances but also paper characteristics by the modification of various factors like molecular design and ionic characteristics of polyacrylamides First of all physical characteristics were observed after modify molecular design of the cationic polyacrylamides to linear, branched and cross-linked. In addition it was found analysis method to confirm branch degree of cationic polyacrylamides to combine ionic titration characteristics and spectroscopic behavior, After application of these structure modified polyacrylamides to the multiple retention systems with inorganic microparticles, it was found adjusting of branch degree of polyacrylamides was very important to optimize wet-end improvement. Second, After polymerization of amphoteric polyacrylamide to have both of cationic and anionic functional group in the polymer, we observed not only physical characteristics but also wet-end improvement to apply recycled pulp and found that the improvement of solution stability to prevent hydrolysis and increase of ash retention dramatically to compare traditional cationic polyacrylamide retention aid, Finally, After polymerization of anionic polyacrylamide, we observed not only wet-end improvement but also paper characteristics to apply preflocculation of PCC and it was found the improvements of flocculation efficiency, retention, ash retention, optical properties of the paper and bursting strength to compare traditional preflocculant of cationic polyacrylamide.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.364-372
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• 2023

By applying coarse-grained limestone and unprocessed coal ash as sintering raw materials for cement clinker, the microstructure and distribution of chemical components of cement clinker were compared and examined. Samples using coarse limestone as a raw material for cement clinker showed a decrease in sinterability compared to samples using reagent-grade raw materials. Samples using coal ash showed a tendency for some increase in sinterability. In samples using coarse limestone and coal ash, the formation of Belite was high at 1350 ℃. The conversion rate from Belite to Alite was high in the range of 1350~1450 ℃. Samples using coal ash showed stable formation of interstitial phase in the range of 1350 to 1450 ℃. The microstructure and chemical composition distribution of cement clinker sintered at 1350~1450 ℃ showed that all samples showed a form and composition distribution in which the calcium silicate phase and interstitial phase were clearly distinguished.