• 대한건축학회논문집:구조계
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• 제34권7호
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• pp.19-26
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• 2018

This study tested 25 lightweight aggregate concrete (LWAC) mixtures using the expanded bottom ash and dredged soil granules to examine the compressive strength gain of such concrete with different ages. The test parameters investigated were water-to-cement ratios and the natural sand content for the replacement of lightweight fine aggregate. The compressive strength gain rate in the basic equation specified in fib model code was experimentally determined in each mixture and then empirically formulated as a function of the water-to-cement ratio and oven-dried density of concrete. When compared with 28-day compressive strength, the tested LWAC mixtures exhibited relatively low gain ratios (0.49~0.82) at an age of 3 days whereas the gain ratios (1.16~1.41) at 91 days were higher than that (1.05~1.15) of the conventional normal-weight concrete. Thus, the fib model equations tend to overestimate the early strength gain of LWAC but underestimate the long-term strength gain. The proposed equations are in good agreement with the measured compressive strength development of LWAC at different ages, indicating that the mean and standard deviation of the normalized root mean square errors determined in each mixture are 0.101 and 0.053, respectively.

• 한국건축시공학회지
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• 제7권1호
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• pp.115-121
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• 2007

Ordinary concrete uses aggregate sufficiently soaked with water, and is weighed, mixed with other materials and placed in accord with performances required in the construction field. Recently special concrete with high fluidity and durability is required but it is difficult to use top-quality concrete due to lack of high-quality aggregate, delayed transportation because of traffic jam, etc. In addition, sometimes the use of a remicon is inevitable just for small-sized concrete constructions or it is difficult for a remicon to reach remote construction places such as mountainous areas. To solve these problems, this study attempted to pack concrete materials. In other words, it is to instantize concrete. This study dried aggregate, a material of concrete, and compared the change of absorption phase of the aggregate in water and in paste in order to examine the effect of the dryness of aggregate on its absorption rate and, based on the absorption rate, decided water addition ratio necessary for the reduction of unit quantity caused by the use of dry aggregate in designing concrete mixture, and analyzed the properties of unhardened concrete according to water addition ratio in manufacturing concrete using aggregate in the state of absolute dryness and in the state of surface dryness.

• 한국건설순환자원학회논문집
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• 제7권2호
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• pp.84-90
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• 2012

폐목재의 활용에 관한 특허동향 분석을 위해 한국특허정보원의 특허정보검색서비스(KIPRIS)에서 관련 키워드로 한국, 미국 및 일본의 특허 검색을 실시하여 2011년 12일 31일까지 특허 등록된 한국 77건, 미국 316건 및 일본 317건의 특허 자료를 수집하였다. 수집된 자료 중 거절, 소멸, 무효, 취하, 포기 및 폐목재와 관련이 적은 내용의 특허를 제외시키고 얻은 한국특허 71건, 미국특허 216건, 일본특허 227건에 대한 분석을 실시하였다. 또한 폐목재를 콘크리트용 경량골재로 활용하기 위한 기초 연구로서 파쇄시킨 소나무 임목부산물을 No. 8(2.4 mm)체로 쳐서 이를 통과시킨 것을 $100{\pm}5^{\circ}C$에서 24시간 동안 건조시킨 다음 잔골재의 일부로서 대체 사용한 모르타르 물성 실험을 실시하였다. 목재와 시멘트를 혼합하는 경우 목재의 수종과 부위에 따라서는 시멘트의 경화를 저해하는 것으로 알려져 있기 때문에 본 연구에서는 파쇄폐목재를 $20^{\circ}C$, $50^{\circ}C$, $80^{\circ}C$ 및 $100^{\circ}C$의 수중에서 일정 시간 동안 침지시킨 후 건조시킨 다음 이를 사용한 모르타르의 물성실험을 실시하여 파쇄폐목재의 전처리 효과를 함께 고찰하였다.

• 아시안잔디학회지
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• 제25권1호
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• pp.69-72
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• 2011

토양입단화는 토양의 물리적 화학적 그리고 생물학적인 변화를 일으키는 활발한 과정이다. 토양입단화를 통해서 생성된 토양공극은 토양에서 공기와 물의 순환을 증가시키는 역할을 하게 된다. 유기중합물이 토양입단 안정화에 대한 긍정적인 역할은 많은 연구결과에서 보고가 된 바 있다. 본 실험의 목적은 유기중합물이 토양입단화와 페레니얼 라이그래스의 성장에 미치는 영향에 대해서 알아보기 위해서 수행되었다. 유기중합물의 세가지 농도가 적용이 되었으며 실험을 위해 두가지 토양이 사용이 되었다. 첫번째 토양으로 4.0%의 유기물이 함유된 양토가 건조된 후 사용이 되었으며 두번째 토양으로 점토가 사용이 되었다. 유기중합물 처리에 따른 페레니얼 라이그래스의 색, 품질, 성장에 미치는 영향은 나타나지 않았다. 그러나 유기중합물이 토양입단화에는 토양의 종류에 따라 영향이 있는 것으로 나타났다. 본 실험의 결과의 구체적인 실증을 위해서 필드 실험이 필요한 것으로 판단이 된다.

• Advances in materials Research
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• 제11권4호
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• pp.299-330
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• 2022

This review article highlights the physical, mechanical, and chemical properties of coconut shells, and the fresh and hardened properties of the coconut shell concrete are summarized and were compared with other types of aggregates. Furthermore, the structural behavior in terms of flexural, shear, and torsion was also highlighted, with other properties including shrinkage, elastic modulus, and permeability of the coconut shell concrete. Based on the reviewed literature, concrete containing coconut shell as coarse aggregate with normal sand as fine showed the 28-day compressive strength between 2 and 36 MPa with the dried density range of 1865 to 2300 kg/m³. Coconut shell concretes showed a 28-day modulus of rupture and splitting tensile strength values in the ranges of 2.59 to 8.45 MPa and 0.8 to 3.70 MPa, respectively, and these values were in the range of 5-20% of the compressive strength. The flexural behavior of CSC was found similar to other types of lightweight concrete. There were no horizontal cracks on beams which indicate no bond failure. Whereas, the diagonal shear failure was prominent in beams with no shear reinforcements while flexural failure mode was seen in beams having shear reinforcement. Under torsion, CSC beams behave like conventional concrete. Finally, future recommendations are also suggested in this study to investigate the innovative lightweight aggregate concrete based on the environmental and financial design factors.

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권1호
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• pp.25-29
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• 2018

The effect of soil grinding on total As and Pb concentrations determined by aqua regia method was examined. Among six field-collected, air-dried soil samples tested, soils A, B, C, and E were directly sieved through a $150-{\mu}m$ sieve without grinding and showed 2.18 to 3.03 times higher total As concentrations and 2.62 to 3.45 times higher total Pb concentrations than those of the soil samples prepared to allow all soil particles to pass through the $150-{\mu}m$ sieve by grinding. The reason can be ascribed to the fact that those soils contain fine particles (i.e., < $150{\mu}m$ in diameter) only 4.6 to 6.8% of the total soil weights. On the other hand, for D and F soils, fine particles smaller than $150{\mu}m$ accounted for 57 and 46%, respectively, so that the effect of grinding on As and Pb concentrations were relatively low (As: 1.15 and 1.23 times, Pb: 1.36 and 1.49 times, respectively). The result demonstrates that grinding prior to $150-{\mu}m$ sieving is necessary to ensure the homogeneity of soil samples and hence to obtain more accurate heavy metal concentrations in soils. This is especially true for soil samples with less fine soil particles and/or microaggregates (i.e., below $150{\mu}m$).

• 한국건설순환자원학회논문집
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• 제4권2호
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• pp.165-171
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• 2016

본 연구에서는 에코 프리캐스트 콘크리트 제품 개발을 위한 기초 연구로서 박테리아를 흡착한 팽창질석 기반의 친생태 모르타르를 개발하였으며, 압축강도 발현 및 생태환경영향 평가를 실시하였다. 경화된 모르타르의 극건조 환경 및 강알칼리성 환경에서 생장이 가능하며, 식물생장성 증대 효과를 갖는 Bacillus alcalophilus와 Rhodoblastus acidophilus를 분리 및 배양하였다. 배양이 완료된 박테리아는 생장처 제공을 위한 재료로서 선택된 팽창질석에 흡착하였으며, 이를 배합시 골재의 체적 대비 혼입하여 모르타르를 제작하였다. 평가 결과 친생태 모르타르는 COD 및 T-N 수질정화능력 및 식물생장증대에 효과를 보였다. 모르타르의 압축강도 발현 및 비용적 측면을 고려했을 때, 박테리아 기반 팽창질석의 최적 치환율은 최대 10% 이하가 추천될 수 있었다.

• Journal of Forest and Environmental Science
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• 제37권2호
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• pp.116-127
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• 2021

Predicting carbon distribution of soil aggregates is difficult due to complexity in organo-mineral formation. This limits global warming mitigation through soil carbon sequestration. Therefore, knowledge of land use effect on carbon stabilization requires quantification of soil mineral cations. The study was conducted to quantify carbon and base cations on soil mineral fractions in Natural Forest, Plantation Forest and Farm Land. Five 0.09 ha were demarcated alternately along 500 m long transect with an interval of 50 m in Natural Forest (NF), Plantation Forest (PF) and Farm Land (FL). Soil samples were collected with soil cores at 0-15, 15-30 and 30-45 cm depths in each plot. Soil core samples were oven-dried at 105℃ and soil bulk densities were computed. Sample (100 g) of each soil core was separated into >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.05 and <0.05 mm aggregates using dry sieve procedure and proportion determined. Carbon concentration of soil aggregates was determined using Loss-on-ignition method. Mineral fractions of soil depths were obtained using dispersion, sequential extraction and sedimentation methods of composite soil samples and sieved into <0.05 and >0.05 mm fractions. Cation exchange capacity of two mineral fractions was measured using spectrophotometry method. Data collected were analysed using descriptive and ANOVA at α_0.05. Silt and sand particle size decreased while clay increased with increase in soil depth in NF and PF. Subsoil depth contained highest carbon stock in the PF. Carbon concentration increased with decrease in aggregate size in soil depths of NF and FL. Micro- (1-0.5, 0.5-0.05 and <0.05 mm) and macro-aggregates (>2.0 and 2-1.0 mm) were saturated with soil carbon in NF and FL, respectively. Cation exchange capacity of <0.05 mm was higher than >0.05 mm in soil depths of PF and FL. Fine silt (<0.05 mm) determine the cation exchange capacity in soil depths. Land use and mineral size influence the carbon and cation exchange capacity of Gambari Forest Reserve.