• Resources Recycling
• /
• v.9 no.6
• /
• pp.36-44
• /
• 2000

Fly ash was composed of the unburned carbon and mineral particles. The former was able to attach on the bubbles, while the latter was not. Therefore, it was possible to separate the unburned carbon and the mineral from fly ash using the froth flotation process. This study was carried out to evaluate the separation efficiency as a function of the ny ash particle properties in the column flotation. Separation efficiency was analyzed for various size fraction of -38 fm,38~125 fm and 1125 W, and for various fly ash samples containing 7, 11, and 20 wt% unburned carbon. For the size fractions of -38 fm containing 7 wt% unburned carbon, separation efficiency was 86ft, whereas separation efficiency was found to be 74% for the size fraction of +125$\mu\textrm{m}$ containing 20 wt% unburned carbon. The results indicated that separation efficiency increased with the decrease in the particle size and the unburned carbon content of the fly ash.

• Journal of Environmental Science International
• /
• v.26 no.11
• /
• pp.1267-1274
• /
• 2017

A Controlled Low-Strength Materials (CLSM) is suitable for mine backfilling because it does not require compaction owing to it high fluidity and can be installed quickly. Therefore, a CLSM utilizing $CO_2$-solidified Circulating Fluidzed Bed Combustion (CFBC) coal ash was developed and it's properties were investigated, since. $CO_2$-solidification of CFBC coal ash can inhibit exudation of heavy metals. The chemical composition and specific surface area of Pulverized coal Combustion fly ash and CFBC fly ash were analyzed. The water ratio, compressive strength and length change ratio of CLSM were confirmed. The water ratios differed with the specific surface area of the CLSM. It was confirmed that the porosity of CLSM affected its compressive strength and length change ratio.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.2
• /
• pp.154-160
• /
• 2018

Cement industries are considered key industries for reducing carbon emissions, and efforts are off the ground to reduce the use of cement in the concrete sector. As a part of this effort, research is off the ground to utilize a large amount of industrial by-products that can be used as a substitute for a part of cement. Concrete using industrial by-products has advantages such as durability, environment friendliness and economical efficiency, but there are problems such as retarding and early-age strength deterioration. Therefore, this study aimed to reduce the use of cement and solve the problem of early-age strength deterioration while using fly ash, which is an industrial by-product. Accordingly, it was confirmed that the strength was improved at all ages irrespective of curing temperature by accelerating the hydration reaction by using high fineness cement. Subsequently, high fineness cement was partially replaced with fly ash and the strength development characteristics were examined. As a result, it was possible to exhibit strength equal to or higher than ordinary portland cement even at the early age. Also, it was confirmed that even when the fly ash is replaced by 30%, it is possible to shorten the time for dismantling the forms of vertical and horizontal members.

• Journal of People, Plants, and Environment
• /
• v.24 no.5
• /
• pp.461-468
• /
• 2021

Background and objective: Particulate matter (PM) has a serious impact on health. Recently, studies are conducted to reduce PM in an environmentally friendly way using plants. This study investigated the physiological responses of plants and their ability to remove PM by continuously spraying different PM sources (loam, fly ash, carbon black) to four native plant species, such as Iris sanguinea, Pteris multifida, Vitis coignetiae, and Viburnum odoratissimum var. awabuki. Methods: The four plant species were randomly placed in four chambers, and 0.1 g of different PM was injected into each chamber twice a week. We measured chlorophyll, carotenoid, chlorophyll fluorescence (Fv/Fm), total leaf area, amount of leaf wax, PM10 (sPM10) and PM2.5 (sPM2.5) on the leaf surface, and PM10 (wPM10) and PM2.5 (wPM2.5) on the wax layer. Results: For I. sanguinea and V. coignetiae, the sources of PM did not affect the growth response. P. multifida showed high chlorophyll a, b, total chlorophyll, and carotenoid content in carbon black as well as high Fv/Fm and total leaf area, thereby proving that carbon black helped plant growth. By PM sources, sPM10 showed a significant difference in three plant species, sPM2.5 in two plant species, and wPM10 in one plant species, indicating that sPM10 was most affected by PM sources. Conclusion: Carbon black increased the leaf area by affecting the growth of P. multifida. This plant can be effectively used for PM reduction by increasing the adsorption area. I. sanguinea and V. coignetiae can be used as economical landscaping plants since they can grow regardless of PM sources.

• Resources Recycling
• /
• v.9 no.2
• /
• pp.33-39
• /
• 2000

Low density ceramic supporter was prepared by using fly ash as a starting material for the application to the biological aerated filter system. Wheat powders were used to control the porosity of the supporter and the carbon content of the raw material. Apparent density of 1.6~1.8 g/$\textrm{cm}^3$ was obtained when the fly ash was sintered at $1200^{\circ}C$ in a weak reducing atmosphere. By maintaining the reducing atmosphere and sintering at a high heating rate, the liquid phase was formed from the reduced composition of fly ash. This resulted in the closed pore formation which enabled the low apparent density.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 1999.10a
• /
• pp.65-68
• /
• 1999

A plasma melting system to vitrify ny ash from MSW(Municipal Solid Waste) incinerator has been operated in SHI(Samsung Heavy Industries) since 1996. Waste feeding rate was 200kg/hr. with maximum working power of 500㎾. Because of high melting temperature of fly ash, bottom ash was used as an additive to decrease melting temperature. Data analysis for discharged slag shows volume reduction up to 30% and no leaching of heavy metals such as Pb, Cd, Cr which were an obstacle for landfill and recycle. Atmospheric pollution gas like nitrogen oxides, carbon monoxide, and PCDD/PCDF were restrained below the regulatory limit.

• Journal of the Korea Institute of Building Construction
• /
• v.19 no.4
• /
• pp.323-330
• /
• 2019

The cement industry is considered a major industry for reducing greenhouse gases, increasing the amount of binding materials that can replace cement in concrete is known as the most effective method for reducing carbon dioxide. Therefore, research is being carried out to utilize large quantities of by-products that can be used as alternatives to cement. However, there are problems with reduced strength at early age and retarded setting for major reasons that do not increase the amount of mixture of binders used to replace cement. Thus, in this study, normal cement and high-fineness cement were used and physical properties were reviewed by placing differences in fly ash usage depending on the type of cement. As a result, the characteristics of strength were similar, and the hydration temperature was the same level. Also, the durability test showed that the length change, carbonation resistance were better than those of normal cement. Therefore, it is confirmed that the use of high-fineness cement is effective to reduce the amount of cement used and using more by-products.

• Journal of the Korea Institute of Building Construction
• /
• v.24 no.2
• /
• pp.215-226
• /
• 2024

This study presents an experimental investigation into the performance of self-sensing grout formulated with a high volume of ultra-fine fly ash(UHFA). To explore the potential benefits of alternative cementitious materials, the research examined the effect of substituting UHFA with equal parts of blast furnace slag(BFS) fine powder. Both UHFA and BFS are byproducts generated in significant quantities by industrial processes. The evaluation focused on the fresh properties of the grout, including its flow characteristics, as well as the hardened properties such as compressive strength, dimensional stability(length change rate), and electrical properties. The experimental results demonstrated that incorporating UHFA resulted in a substantial reduction in the plastic viscosity of the grout, translating to improved flowability. Additionally, the compressive strength of the UHFA-modified grout surpassed that of the reference grout(without UHFA substitution) at all curing ages investigated. Interestingly, the electrical characteristics, as indicated by the relationships between FCR-stress and FCR-strain, exhibited similar trends for both grout mixtures.

• Advances in nano research
• /
• v.13 no.1
• /
• pp.13-28
• /
• 2022

The pumpability of the grouts is significant issue in concept of the rheological and workability properties during penetrating to voids and cracks. To improve the fluidity features of the grout mixes, the usage of Colloidal Nano Particular Powders (CNPPs) with mineral additives such as fly ash (FA) can contribute. Therefore, the main purpose of this study can be explained as investigating the usage effects of four types of Colloidal Nano Particular Powders (n-TiO₂, n-ZnO, n-Al₂O₃ and n-SiO₂) as nano additives on the rheological, workability and bleeding properties of cement-based grout incorporated with fly as. Test results showed that the usage of FA in the grout samples positively contribute to increase on the fluidity of the grout samples as expected. The dilatant behavior was observed from the results for all mixes. Observing the effect of nano-sized additives in such cement-based grout mixtures with high fluidity has presented remarkable effects in this study.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.601-604
• /
• 2006

Recently the new inorganic sound-absorbing material manufacturing techniques have introduced. These mainly is plentifully used in the place where the noise damage becomes problem in life environment, partitioning of the apartment, the railroad and the express highway, school and the residential quarter neighboring area etc. While the sound-absorbing material has vast quantity of open pore, sound insulation material, used in the apartment and high building in order to prevent the sound between layers, has suitable quantity of closed pore. The fly ash is widely used in the cement materials and the concrete binder material. The bottom ash, however, is rarely used for the grain size is big and multiform with unburning carbon ingredient. In this paper, the practical field tests and the results on the sound reduction properties of formed concrete using bottom ash are described.