• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.3
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• pp.151-158
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• 2007

The recent government policy for environment is pursuing for a circular waste control system not only to reduce waste as much as possible but also to vigorously use the already produced waste. Copper slag has a higher fineness modulus and a greater specific gravity than natural aggregate. but when the substitutive ratio of fine aggregate is higher than 30%, material segregation occurs by bleeding. Thus, in this study, the strength and the physical properties were tested for the specimens manufactured by varying the types of admixtures, and the substitutive ratio of copper slag to suppress material segregation occurring due to the bleeding of concrete using copper slag as the substitutive material of fine aggregate and to find the adequate substitutive ratio of copper slag.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.349-355
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• 2016

This study is about the reuse of bottom ash, which is released as a necessity in thermal power plant. In general, coal-ash are classified as fly-ash, bottom-ash, cinder-ash. Of these, a large amount of fly ash is being recycled as cement substitutes. While, recycling rates of bottom ash are the lowest due to its porosity and high absorption. In this study, the durability of the concrete using bottom ash as a concrete fine aggregate was evaluated. The using level of the bottom ash ranges to step-by-step from 0% to 30%. According to the result of the durability test, regardless of the presence of the bottom ash, freeze-thaw durability could be secured by air entrainment. In case of the resistance to chloride ions penetration, the length change, and the effects on heavy metals, the replacement of bottom ash as fine aggregate was not critical. Although carbonation penetration was higher as the replacement level of bottom ash increased, the experiment showed that it could be possible to use bottom ash as concrete fine aggregate with proper mix design.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.167-174
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• 2020

Many researches have been conducted to utilize recycled aggregates in Korea, but since most sources of recycled aggregates are not clear, there is a lot of uncertainty in applying the existing research results on recycle of aggregates generated from nuclear power plants. In this study, therefore, in order to investigate the possibility of recycling coarse aggregates generated through dismantling of nuclear power plants in Korea, recycled coarse aggregates were produced from concrete simulating nuclear power plants in Korea. Using the recycled coarse aggregates, concrete was mixed in consideration of the mixing ratio of the recycled coarse aggregates, and the mechanical properties were experimentally investigated. From the test results, as the mixing ratio of recycled coarse aggregates increased. concrete compressive strength, tensile strength, and elastic modulus generally decreased up to 36, 37, and 27% from the mechanical properties of normal concrete, respectively. Therefore, it can be concluded that limitation on the mixing ratio of recycled coarse aggregates is necessary when coarse aggregates are recycled through dismantling of nuclear power plants.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.63-69
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• 2020

The volume of construction waste material from the entire waste material volume in Korea is approximately 47.3% to take the biggest ratio, and from them, the waste concrete takes up approximately 62.8% that recycling is an urgent issue to address. Therefore, the government recommends more diverse and broader facilitation of the recycled aggregate in order to promote recycling the construction waste materials. In addition, when using concrete recycled aggregate in building, building standard such as floor area ratio and building height are being mitigation. The standard is a condition that mitigation the floor area ratio by up to 15% when using up to 25% of concrete recycled aggregate. Therefore, this study reviewed the relaxation of construction of construction standards when using concrete recycled aggregate in order to actively recommend the use of concrete recycled aggregate. And using the recycled coarse aggregate among the recycled aggregate, the appropriate mixing time in the batch plant according to the substitution rate was derived. In addition, using recycled aggregate admixture in order to improve the drying shrinkage, did comparative analysis about physical and mechanical property of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.253-254
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• 2010

This study is about evaluation of shrinkage of concrete used oxidized EFS(electric-furnaceslag) aggregate. As a result, the shrinkage of concrete used oxidized EFS aggregate is decreased to about 40% in proportion to replacement of oxidized EFS aggregate in total aggregate volume.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.329-334
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• 2005

The use of Polymer Concrete (PC) is growing very rapidly in many structural and construction applications such as box culverts, hazardous waste containers, trench lines, floor drains and the repair and overlay of damaged cement concrete surfaces in pavements, bridges, etc. However, PC has a defect economically because resin which be used for binder is expensive. Therefore the latest research is being progressed to replace existing resin with new resin which can reduce the high cost. Here, Polymer concrete using the recycled PET(polyethylene terephthalate) has some merits such as decrease of environmental destruction, decrease of environmental pollution and development of new construction materials. The variables of this study are amount of resin, curing condition and maximum size of coarse aggregate to find out mechanic properties of this. Stress-strain curve was obtained using MTS equipment by strain control. The results indicated that modulus of elasticity was increased gradually in an ascending branch of curve, as an increase of resin content. Compressive strength was the highest for resin content of $13\%$. And Compressive strength was increased as maximum size of coarse aggregate increases. The strain at maximum stress increases with an increase of resin content and size of coarse aggregate. For the descending branch of stress-strain curve the brittle fracture was decreased when it was cured at the room temperature compared to high temperature.

• Resources Recycling
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• v.29 no.2
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• pp.28-36
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• 2020

To enhance the recycling rate of wasted glass bottles toward recycled aggregates, the study would decide optimal comminution equipment based on the particle size distribution, aspect ratio and equipment energy analysis. The impact, compress and abrasion is type of generated force by comminution. So, hammer crusher, shredder, roll crusher and ball mill have been selected because they have characteristic which is each type of force. As a result of the particle size analysis of each product, only the shredder product satisfied concrete and asphalt aggregate quality standard condition. Also, as a result of aspect ratio analysis using Imaging software program (Image J, National institute of health), most of size fraction is confirmed under 1.6 value. It was confirmed that the product has low dangerousness and satisfying to shpage index. Also, the particle reduction ratio against input energy of shredder product was the most high. Therefore, we can decide that the optimal equipment which applicable for comminuting waste glass bottle in certain particle size under 10mm is shredder. The result of study will make contribution to increasing energy efficiency of comminution processing and competitiveness of product.

• Economic and Environmental Geology
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• v.50 no.4
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• pp.257-266
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• 2017

Batch experiments were performed to develop the method for the pH reduction of recycled aggregate by using $scCO_2$ (supercritical $CO_2$), maintaining the pH of extraction water below 9.8. Three different aggregate types from a domestic company were used for the $scCO_2$-water-recycled aggregate reaction to investigate the low pH maintenance of aggregate during the reaction. Thirty five gram of recycled aggregate sample was mixed with 70 mL of distilled water in a Teflon beaker, which was fixed in a high pressurized stainless steel cell (150 mL of capacity). The inside of the cell was pressurized to 100 bar and each cell was located in an oven at $50^{\circ}C$ for 50 days and the pH and ion concentrations of water in the cell were measured at a different reaction time interval. The XRD and SEM-EDS analyses for the aggregate before and after the reaction were performed to identify the mineralogical change during the reaction. The extraction experiment for the aggregate was also conducted to investigate the pH change of extracted water by the $scCO_2$ treatment. The pH of the recycled aggregate without the $scCO_2$ treatment maintained over 12, but its pH dramatically decreased to below 7 after 1 hour reaction and maintained below 8 for 50 day reaction. Concentration of $Ca^{2+}$, $Si^{4+}$, $Mg^{2+}$ and $Na^+$ increased in water due to the $scCO_2$-water-recycled aggregate reaction and lots of secondary precipitates such as calcite, amorphous silicate, and hydroxide minerals were found by XRD and SEM-EDS analyses. The pH of extracted water from the recycled aggregates without the $scCO_2$ treatment maintained over 12, but the pH of extracted water with the $scCO_2$ treatment kept below 9 of pH for both of 50 day and 1 day treatment, suggesting that the recycled aggregate with the $scCO_2$ treatment can be reused in real construction sites.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.316-323
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• 2023

The need for sustainable waste management has intensified the focus on recycling prestressed concrete sleepers used in railways. Given their high volume and environmental impact at the end of their service life, finding efficient recycling methods is crucial. This study explores current recycling approaches, particularly mechanical techniques, evaluating their advantages, limitations, and economic feasibility. Finally, an example of mechanical recycling was performed. The analysis results of the resulting recycled aggregates are suggested. Then, the non-cement concrete mixtures with recycled aggregates were designed, and their strength development was analyzed.

• Resources Recycling
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• v.25 no.2
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• pp.49-59
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• 2016

Steel slag is being recycled into industrial by-products for civil generated inevitably in the seasonal course, road and cement raw materials. However, the field of recycling most of the bottom portion is concentrated in the areas that are required to take advantage of the situation in various fields taking advantage of the steel slag. But various studies to take advantage of the steel slag as aggregate for concrete made for limiting slag was a situation that most of the studies are incomplete research on the suitability of as aggregate for concrete practical relates to an expandable suppressed. In this study, the separation of the slag aggregate according to the production methods to assess the feasibility aggregate for concrete aggregates, including through Steel making slag, a total of seven kinds of steel slag aggregate. Studies show that ordinary concrete, steel slag aggregate for aggregate and on the equally to take advantage of grading, chloride content standards such as to what is lacking, although appropriate aggregate of concrete include the deployment of only in special sectors through the combination was assessed to have a very high.