Properties of Non-Sintered Cement Mortar Made with Activated Hwangto 비소성 시멘트의 활성황토 치환에 따른 모르타르의 특성 변화
김무준 Moo-joon Kim , 문경주 Kyoung-ju Mun , 형원길 Won-gil Hyung
DOI:10.9786/kswm.2020.37.2.85
Abstract
In construction sectors, activities using cement emit a significant amount of carbon dioxide accounting for approximately 30% of global CO2 emissions. Therefore, the use of cement in construction sectors needs to be reduced in order to reduce CO2 emissions. In this regard, herein the properties of non-sintered cement mortar made with ground granulated blast furnace slag, high calcium fly ash, and activated Hwangto were characterized to find proper eco-friendly replacement of cement. Flow test results of non-sintered cement mortar indicated a tendency for water/binder ratio is increased with the rate of adding activated Hwangto. When activated Hwangto was added, flexural and compressive strength was 20% (HFAH-20). Absorption rates was also increased with the addition of activated Hwangto. The neutralization test showed that the nonsintered cement mortar made with activated Hwangto is responded. X-ray diffraction analysis showed that as activated Hwangto is added, stratlingite was increased but Ca(OH)2 was decreased. Through scanning electron microscope analysis, a small amount of ettringite and calcium-silicate-hydrate gels was found, but no plate-like Ca(OH)2 were observed.
Characterization of Bio-coal Made via Hydrothermal Carbonization of Mixed Organic Waste Hydrothermal Carbonization (HTC)을 이용한 혼합 유기성폐기물 bio-coal의 특성 평가
김형욱 Hyeong Wook Kim , 조우리 Woori Cho , 이재영 Jai-young Lee
Characterization of Bio-coal Made via Hydrothermal Carbonization of Mixed Organic Waste Hydrothermal Carbonization (HTC)을 이용한 혼합 유기성폐기물 bio-coal의 특성 평가
김형욱 Hyeong Wook Kim , 조우리 Woori Cho , 이재영 Jai-young Lee
DOI:10.9786/kswm.2020.37.2.93
Abstract
In this study, a mixture of sewage sludge, paper sludge, and food waste was hydrothermally carbonized to produce a renewable solid fuel. Hydrothermal carbonization (HTC) does not need a drying step, so it is a proper method to make biofuels from wet feedstocks. Fuel properties of the bio-coals produced via HTC of mixtures of sewage sludge, paper sludge, and food waste with different ratios were characterized. As the ratio of food waste in the mixture was increased, the content of fixed carbon and heating value were increased. Coal banding analysis proved that the ratio of carbon/ hydrogen/oxygen of the bio-coals were similar to those of a low-grade coal.
The Environmental Assessment of Recycling (EAoR) system protects humans and the environment from the pollution that results from recycling. Under the EAoR system, the Eco-Toxicity test applies to land-based (e.g., filling material) recycling larger than 120,000 tons or 30,000 m2 for recycling plants as defined by current laws (for new recycling methods currently undefined, the eco-toxicity test should always be applied regardless of size and weight). The eco-toxicity limit is less than TU 2.0 on the acute toxicity test by Daphnia magna. This study used the up-flow percolation method to get liquid samples from solid wastes for testing. We also analyzed heavy metals and other factors to evaluate their recyclability. Our results showed that 3 out of 5 waste types exceeded the toxicity limit. The maximum toxicity value was TU 44.4 in the incinerator. Heavy metal analysis proved that the content of Cr6+ in the waste exceeded the standard; hence, it can be highly toxic.
Key Words
Environmental assessment of recycling, Eco-toxicity test, Up-flow percolation method
Study on the Physical Properties of Recycled Aggregate Concrete with Variation of Mixing Rate and Cement Content 순환골재 혼합비율 및 시멘트량 변화에 따른 순환골재 콘크리트의 물리적 특성에 관한 연구
Study on the Physical Properties of Recycled Aggregate Concrete with Variation of Mixing Rate and Cement Content 순환골재 혼합비율 및 시멘트량 변화에 따른 순환골재 콘크리트의 물리적 특성에 관한 연구
이세현 Sea-hyun Lee
DOI:10.9786/kswm.2020.37.2.109
Abstract
This study compared and analyzed the physical characteristics of slump, air volume, and compressive strength according to the cyclic aggregate mixing ratio and the change of cement. According to the circulating aggregate, the slump showed satisfactory results of 190 ± 15 mm, which is the standard in all formulations. In addition, the change in air volume over the plain showed a similar pattern. The compressive strength of circulating aggregate concrete showed the same strength as the plain, and the application of circulating aggregate did not lead to no significant decrease in strength. We concluded that achieving the target strength of 27 MPa would require about 10 kg/m3 more cement than that of general concrete.
Study on the Engineering Evaluation of Waste PET as a Construction Material 건설재료로 재활용하기 위한 폐PET의 공학적 평가에 관한 연구
김유성 You-seong Kim , 이강수 Khang-soo Lee , 조대성 Dae-sung Cho
DOI:10.9786/kswm.2020.37.2.117
Abstract
Polyethylene terephthalate (PET) is a polyester resin produced by the condensation reaction between terephthalic acid and ethylene glycol. Since it has excellent engineering properties such as thermal stability, transparency, and strength, the consumption for packaging containers increases every year; in turn, waste PET increased. It is difficult to recycle PET due to the lack of facilities, which makes waste PET a source of environmental pollution. In this study, we analyzed the engineering properties of waste PET to explore the possibility of using it as an alternative to concrete, the latter of which produces carbon dioxide emissions and causes environmental damage by collecting natural aggregates. We found that the compressive strength of waste PET was 32.89MPa, tensile strength was 31.43 MPa, Izod impact strength was 2.68 kJ/m2, and Rockwell hardness was 122.17. These results showed that the compressive strength was equivalent to that of ordinary concrete, and the tensile strength and hardness were better. However, the impact strength was low. Also, waste PET showed a lack of resistance to dynamic loads acting suddenly in various directions. However, in the static load condition such as the weight of soil, we found that the cross-section is simple such as pile foundation, culvert, block, and waste pipe, and waste PET can be used as construction materials manufactured using concrete.
Evaluation of Parameters Affecting Composting of Hanwoo Manure 한우분뇨 퇴비화 시 공기공급량 및 퇴비화 경과 시간에 따른 퇴비특성 평가
이성현 Sunghyoun Lee , 정광화 Gwanghwa Jeong , 이동준 Dongjun Lee , 이동현 Donghyeon Lee , 곽정훈 Junghoon Kwag
DOI:10.9786/kswm.2020.37.2.124
Abstract
Hanwoo (a breed of small cattle native to Korea) manure is a major byproduct generated in farms in Korea. As an effort to exploit the organic waste, this study assesses the feasibility of composting of Hanwoo manure. For the composting test, a control pile, which did not supply air, and two test piles supplying 100 L/m3/min (EXP1) and 150 L/m3/min (EXP2) of outside air, respectively, were installed. Fermentation and post-fermentation lasted for a total of 8 weeks, and samples were collected every week beginning with the initiation of composting. The inner temperature of composting piles EXP1 and EXP2 rapidly increased to 50 ~ 70℃ within 1 ~ 2 d. No significant difference was found in the moisture content, N content, pH, and C/N ratio. The organic matter content was highest in EXP1 and lowest in the control pile. The compost maturity in this study was assessed using a seed germination index wherein 70 or greater is considered to be fully matured compost. The seed germination index of the raw material was initially greater than 100; after 8 weeks of composting, it was 116 ~ 154. In addition, the seed germination index during the composting period exhibits a U-shaped pattern. According to our results, the composting process of the aerated static pile compost had a significant effect on reducing the time required for composting. Thus, supplying an adequate amount of air to compost Hanwoo manure greatly reduces the composting period.
Evaluation of SNCR Performance on NOx Removal by Different Injection Points of Reductant in a Coal-fired CFBC Boiler 석탄 CFBC보일러의 환원제 주입위치에 따른 SNCR 효율특성 연구
Evaluation of SNCR Performance on NOx Removal by Different Injection Points of Reductant in a Coal-fired CFBC Boiler 석탄 CFBC보일러의 환원제 주입위치에 따른 SNCR 효율특성 연구
SNCR (Selective Non Catalytic Reduction) technology is a post-combustion control technology for reducing NOx that injects ammonia reductant into the appropriate position of a boiler furnace. In this study, coal CFBC (Circulating Fludized Bed Combustion) (200 MW), was conducted to obtain the optimum desorption efficiency according to the location of the reducer injection within the temperature range from 850°C to 1,150°C. The performance test at the entrance to the cyclone inlet showed that the average NOx was 50.80 ppm before and 36.93 ppm after reducer injection, respectively. Thus, the average NOx removal efficiency is 27.30%. These results do not satisfy the SNCR performance condition of 30 ppm nor signify a denitrogenation efficiency of greater than 50%. In the cyclone outlet, the NOx removal efficiency was measured at an average of 49.16 ppm before the reducer was injected at an average rate of 21.15 ppm, corresponding to an average reduction of 56.97% after the reducer was injected, which does not exceed the SNCR performance satisfying condition (30 ppm emission concentration of NOx) and corresponds to a desorption rate of greater than 50%. The principal reason for the low denitrogenation efficiency found at the cyclone inlet is that the delayed combustion of the anthracite fuel caused continuous combustion at the seal pot of the cyclone bottom, which is potentially affected the desorption efficiency due to decomposition at high temperature. Therefore, it is desirable to install the optimal reductant for applying SNCR in circulating fluidized bed boilers that use less volatile and combustible anthracite in the cyclone outlet, where delayed combustion does not occur.
Key Words
SNCR, CFBC. NOx Reduction, Urea, Coal
Study on In-situ Hydrogen Sulfide Reduction for Optimal Use of Landfill Gas (LFG) 매립가스(LFG) 최적이용을 위한 In-situ 황화수소(H2S) 저감 연구
오화수 Hwa-soo Oh , 김형수 Hyung-soo Kim , 박정현 Jung-hyun Park , 이영민 Young-min Lee
Study on In-situ Hydrogen Sulfide Reduction for Optimal Use of Landfill Gas (LFG) 매립가스(LFG) 최적이용을 위한 In-situ 황화수소(H2S) 저감 연구
오화수 Hwa-soo Oh , 김형수 Hyung-soo Kim , 박정현 Jung-hyun Park , 이영민 Young-min Lee
DOI:10.9786/kswm.2020.37.2.141
Abstract
The traditional single vertical landfill gas collection system applied to landfills in the Republic of Korea does not efficiently extract the landfill gas. In addition, the system inefficiently treats hydrogen sulfide. This study shows that an efficient, environmentally friendly, and economically-feasible outcome can be achieved by installing an in-situ layer (waste concrete) that can remove hydrogen sulfide from the landfill.
Key Words
Landfill gas, Landfill final cover, Hydrogen sulfide, H2S removal layer
