• Magazine of RCR
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• v.5 no.2
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• pp.35-39
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• 2010

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.77-84
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• 2023

As the installation of solar panel accelerates, so does the number of solar panels reaching their end-of-life (EOL). However, the EOL solar panels is becoming a concern, as they contain potentially hazardous materials and are not easily recycled. Coping strategies such as effective collection, disposal, and recycling methods will be important to manage the growing number of EOL solar panels in the coming years.Therefore, many studies have focused on the development of EOL solar panel recycling technology. One recycling technology for EOL solar panels applicable to the construction field is the application of extracted tempered glass from EOL solar panels as construction materials. This study summarized the EOL solar panel disassembly technology and evaluated the mechanical properties of mortar using extracted tempered glass as fine aggregate. The results showed that when tempered glass was used as a fine aggregate in mortar, the compressive strength, flexural strength, and macro pores in the 1-3 ㎛ with 200-300 ㎛ range were affected, regardless of the disassembly technology of EOL solar panels. Especially, we found that the mechanical performance of mortar using chemically treated tempered glass was noticeably decreased due to changes in the chemical composition of the extracted tempered glass resulting from the removal of K₂O and CuO due to chemical reactions. Meanwhile, it was found that when fly ash was used as a binder, the reduction of mechanical performance could be alleviated.

• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.91-97
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• 2003

At present, the antiwashout underwater concretes are used as popular construction materials in European countries, the United States and Japan. The water-soluble polymers in the antiwashout underwater concretes provide excellent segregation or washout resistance, self-compaction and self-leveling property to the concretes. The purpose of this study is to recommend to optimum mix proportions of antiwashout underwater concretes according to compressive strength of 300kgf/$\textrm{cm}^2$ to 500kgf/$\textrm{cm}^2$. The antiwashout underwater concretes are prepared with various unit cement content, unit water content, sand-aggregate ratio, unit antiwashout agent and superplasticizer content. And they are tested for flowability, and compressive strength. From the test results, it is possible to recommend the optimum mix proportions of antiwashout underwater concretes according to compressive strengths within the range of 300kgf/$\textrm{cm}^2$ to 500kgf/$\textrm{cm}^2$.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.1
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• pp.46-49
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• 2008

Recycling glass fiber, 'F-fiber,' was obtained by the separation of the roving layer from waste FRP and the concrete products or structures were considered for its application. Experiment was carried out for the bending strength of aggregate (2.45 of cement) by weight and F-fiber (density of 1.45, volume ratio to all of the aggregate and the cement). Whereas the specimen containing 1% F-fiber showed the bending strength 23% higher than that without F-fiber after curing far 28 days, the one with 0.5% F-fiber did not give any change. It could be found, therefore, that the minimum mixing amount should be larger than 0.5% fur the strength reinforcement. One of the reinforcing concrete product, bench flume, containing 1% F-fiber showed 21% increment of bending strength In contrast to that without F-fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.923-926
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• 2008

Currently more high flow and high performance concrete is used for construction of buildings in the world. However, when high flow and high performance concrete put high performance water reducing agent in quantity to improve flow, it has a negative effect on concrete structures since segregation arises from it though flow will be improved. There are naked-eye observation, coarse aggregate washing test, L Flow test for permeation among reinforcing rods and measurement of viscosity to judge concrete segregation resistance. However, it is difficult to apply them to practical affairs since they are very complicated and troublesome. Therefore, the study analyzed EIS dividing slump flow value into slump value, how to valuate concrete segregation resistance more easily, on the basis of the existing reference materials to propose EIS. As the results, in the event of high flow concrete, it is desirable that EIS value is prescribed to be less than 2.5 at the time of managing segregation. Also, at the time of prescribing EIS with performance, it is judged that it is desirable to manage segregation as less than 2.2 (Grade 1), 2.2$\sim$2.4 (Grade 2) and more than 2.6 (Grade 3).

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.413-416
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• 2008

The concrete used most in construction materials. There is an overcrowded iron dimensions use of the concrete at time of the other concrete theory on the reinforcing rod back which did congestion and compares it with this, and there are more few dimensions of the aggregate than concrete, and quantity of aggregate passage is superior in mortar than concrete. If a volume rate of the aggregate writes mortar than concrete against this, therefore, unit amount increases, and quantity of paste increases and quantity of dry shrinkage than increase concrete. However, I let I regulate lay priest distribution of the aggregate, and the results rates increase and reduce unit amount and decrease quantity of dry shrinkage, and separation resistance and the gap passage characteristics are judged because it can be it in a substitute document of very superior concrete. I came to carry out the study that I watched to let I was useful a little more and do the improvement repair of a become building wall body, a basement pillar and repair reinforcement of the assistant in the reinforcing rod back, the old age when I made congestion here. I regulated lay priest distribution of the aggregate in the study and regulated substitution rate of the aggregate (40%, 50%, 60%) and divided W/C 30%, 40% standards and produced mortar and I compared quantity of air by this, slump, compression robbery and showed it this time.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.88-94
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• 2011

To make recycling aggregate, quantity of fine particles increase due to multi-crushing. Though this particles were mixed with recycling aggregate, those have to be disparted from aggregate in the high quality recycling aggregate, because of the cause of low quality. Considering reactivity, fine particles is better than coarse one. Therefore, it needs to develop suitable usage. We try to make cement extruding material by using the fine particles from concrete recycling, as a silicious replacement. Test results are as follows ; 1) Waste concrete powder has major ingredients such as $SiO_2$ and CaO, its density is $2.45g/cm^3$ being similar to silica powder, its diameter is range 13 to $141{\mu}m$. 2) Considering to strength properties according to particle size, specimen was made using small particles is higher strength than large one. 3) Despite of exception in the autoclaved curing, when the replacement of waste fine particle increase, strength of extruding panel shows almost same level.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.194-201
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• 2019

This study analyzed the properties of concrete depending on the coal gasification slag(CGS) contents in order to examine the applicability of CGS as the fine aggregate for concrete. Experimental results, trended that the slump and slump flow increased with increasing CGS contents, and air contents has decreased. Evaluation index for segregation of normal strength concrete(EISN) is showed was good from CGS 25% when using crushed sand A(CSa) and CGS 50% when using mixed sand(MS). The compressive strength decreased with increasing CGS contents when CSa was used. However, when MS was used, the maximum value was CGS 50% due to parabolic tendency. Depending on fine aggregates type, compared with compressive strength of CSa was about 8% higher than that of MS, and depending on the use or unuse of CGS, more advantageous at higher strength than low strength. As a result of relative performance study on the quality of concrete according to the CGS contents, it is considered that CGS can be positively contributed to enhancement of workability and strength development when mixed with fine aggregate around 25~50%.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.152-160
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• 2021

Converter steel slag(BOF slag) is a vast amount of solid waste generated in the steelmaking process which has very low utilization rate in Korea. Due to the presence of free CaO which can derive bad volume stability in BOF slag, it usually land filled. For recycling BOF and identify its applicability as fine aggregate, this study investigates the fundamental characteristics of mortar with cement replaced ferronickel slag(FNS), which has the potential to be used as a binder. The results suggest that the mineral phases of BOF slag mainly include larnite(CaSiO₄), mayenite(Ca₁₂Al₁₄O₃₃) and wuestite(FeO) while olivine crystallines are shown in FNS. The results of flow and setting time reveals that the flowability and process of hardening increased when the amount of FNS and BOF slag incorporated was increased. The length change shows that the amount of change in the length of the mortar was almost constant regardless of mix proportion while compressive strength was reduced. Micro structure test results revealed that FNS or/and BOF slag mix took a long time to react in the cement matrix to form a complete hydration products. To achieve the efficient utilization of B OF slag as construction materials, proper replacement rate is necessary.

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.587-592
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• 1995

The purpose of this study was to observe the pattern of bone remodellings in the periodontal ligament of dog, in which experimental tooth movement was performed A control and 5 experimental dogs, one and half year in age, were studied. Light force (50-75g) was applied by placing open-coil spring between left mandibular premolars ; heavy force (250-300g), between right mandibular premolars. Experimental dogs were sacrificed at 12 hours, 1, 3 ,7 and 14 days after force application, respectively. And soft X-ray films were obtained and read on the sectioned periodontal tissue around mandibular premolars. The results were as follows. 1. New bone formation began to be observed in tension side at 7-day and increased at 14-day , No difference was observed between light force group and heavy force group. 2. Bone resorption was observed as a shape of destruction of lamina dura at 3-day and increased gradually at 7-day, 14-day.