• 한국세라믹학회지
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• 제50권2호
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• pp.134-141
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• 2013

Pond ash produced from Seochun Power Station was quantitatively characterized to manufacture geopolymers with a range of Si/Al compositional ratios. Mix consistency was kept nearly constant for comparing the compressive strengths of geopolymers. The amorphous composition of coal ash was determined using XRF and quantitative X-ray diffraction. Different mix compositions were used in order to achieve Si/Al ratios of 2.0, 2.5 and 3.0 in the geopolymer binder. Geopolymers synthesized from coal ash with a Si/Al ratio of 3.0 exhibited the highest compressive strength in this study. It was found that geopolymers activated with aluminate produced different microstructure from that of geopolymers activated with silicate. High silica in alkali activators produced the fine-grained microstructure of geopolymer gel. It was also found that high compressive strength was related to low porosity and a dense, connected microstructure. The outcome of the reported experiment indicates that quantitative formulation method made it possible to choose suitable activators for achieving targeted compositions of geopolymers and to avoid efflorescence.

• 한국미생물·생명공학회지
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• 제32권3호
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• pp.265-270
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• 2004

하수 중계펌프장에서 발생되는 악취를 효율적으로 저감할 수 있는 기술로 4가지 기술(활성탄 흡착법, 약액세정법, 지렁이 분변로를 이용한 탈취법, 바이오필터법)의 탈취 효율과 경제성을 조사하였다. PU 바이오필터와 활성탄 흡착법의 평균탈취 효율은 98% 이상이었으나, 지렁이 분변토 바이오필터와 약액세정법은 60-80%의 탈취율을 보였다. PU 바이오필터 탈취 성능은 악취가스의 체류시간이 4-36초에서 체류시간과 무관하게 약 98-99%로 매우 안정적이었고, 최대 탈취능은 으로 평가되었다. $1.6${\times}$10^{ 7}$ $OUm^{-3}$$h^{-1}$ PU 바이오필터와 활성탄 흡착법의 탈취비용을 조사하였다. 악취 강도가 증가함에 따라 활성탄 흡탁법의 운전비는 선형적으로 증가하였지만 바이오필터법은 약간 증가하였다. 바이오필터의 초기 시설비의 비용이 활성탄 흡탁법의 2배 이상이었지만 운전비가 활성탄 보다 아주 저렴한 것으로 평가되었다. 결론적으로 탈취효율과 경제성이 우수한 생물여과법이 가장 유망한 기술로 평가되었다.

• Environmental Engineering Research
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• 제21권4호
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• pp.341-349
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• 2016

To improve the utilization rate of construction waste as mine backfilling materials, this paper investigated the feasibility of using recycled powder as mine paste backfilling cementitious material, and studied the pozzolanic activity of recycled construction waste powder. In this study, alkali-calcium-sulfur served as the activation principle and an orthogonal test plan was performed to analyze the impact of the early strength agent, quick lime, and gypsum on the pozzolanic activity of the recycled powder. Our results indicated that in descending order, early strength agent > quick lime > gypsum affected the strength of the backfilling paste with recycled powder as a cementitious material during early phases. The strength during late phases was affected by, in descending order, quick lime > gypsum > early strength agent. Using setting time and early compressive strength as an analysis index as well as an extreme difference analysis, it was found that the optimal ratio of recycled powder cementitious material for mine paste backfilling was recycled powder:quick lime:gypsum:early strength agent at 78%:10%:8%:4%. X-ray diffraction analysis and scanning electron microscope were used to show that the hydration products of recycled powder cementitious material at the initial stages were mainly CH and ettringite. As hydration time increased, more and more recycled powder was activated. It mainly became calcium silicate hydrate, calcium aluminate hydrate, etc. In summary, recycled powder exhibited potential pozzolanic activities. When activated, it could replace cementitious materials to be used in mine backfill.

• 한국건설순환자원학회논문집
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• 제7권4호
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• pp.302-309
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• 2019

본 논문은 5℃의 해수 환경에 노출한 알칼리 활성 플라이애시-슬래그 시멘트의 기본 특성에 관한 실험적 연구이다. 플라이애시와 슬래그의 배합비는 6:4, 7:3 및 8:2의 세 가지로 하였으며, 활성화제(수산화나트륨 및 규산나트륨)는 결합재 중량의 5%로 하였다. 실험 결과는 플라이애시의 치환율이 증가할수록 압축강도와 밀도는 감소하는 것으로 나타났으며, 또한 흡수율은 증가하는 것으로 나타났다. 경화된 샘플의 열중량 및 X선 회절분석을 통해 샘플 내에 생성된 반응물의 종류에는 변화가 없었으나, 슬래그의 치환율이 높을수록 C-S-H gel의 생성은 증가한 것을 알 수 있었다. 본 연구에서는 5℃의 해수에 노출된 알칼리 활성 플라이애시-슬래그 시멘트에서 플라이애시 보다 오히려 슬래그의 치환율이 샘플의 역학적 특성에 영향을 미치는 것으로 나타났다.

• Geomechanics and Engineering
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• 제16권1호
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• pp.105-112
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• 2018

This paper presents results of a compressive investigation conducted on weathered soil stabilized with ground bottom ash (GBA) and red mud (RM). The effects of water/binder ratio, RM/GBA ratio, chemical activator (NaOH and $Na_2SiO_3$) and curing time on unconfined compressive strength of stabilized soils were examined. The results show that the water/binder ratio of 1.2 is optimum ratio at which the stabilized soils have the maximum compressive strength. For 28 days of curing, the compressive strength of soils stabilized with alkali-activated GBA and RM varies between 1.5 MPa and 4.1 MPa. The addition of GBA, RM and chemical activators enhanced strength development and the rate of strength improvement was more significant at the later age than at the early age. The potential environmental impacts of stabilized soils were also assessed. The chemical property changes of leachate from stabilized soils were analyzed in terms of pH and concentrations of hazardous elements. The observation revealed that the soil mixture with ground bottom ash and red mud proved environmentally safe.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.473-474
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• 2010

C-S-H(I)은 활성슬래그시멘트의 강도생성의 핵심물질이며 시멘트 수화물의 강도원천물질인 C-S-H의 구조모델로 사용되어 왔기 때문에, 나노 수준의 콘크리트 연구 분야에서는 세계적으로 아주 중요한 물질로 다루어지고 있다. 이러한 C-S-H(I)에서 발생되는 Si에 대한 Al 치환은 C-S-H(I)의 분자구조변경을 인위적으로 할 수 있다는 점에서 주목되어 왔고, C-S-H(I)의 기계적 물성치 (예, bulk modulus)에도 큰 영향을 미칠 것이라고 예상되어 왔었다. 그러나 본 연구를 통해 이러한 Al 치환이 실제로는 C-S-H(I)의 bulk modulus에는 거의 영향을 미치지 못함이 밝혀졌다.

• Advances in materials Research
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• 제4권1호
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• pp.45-60
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• 2015

This paper aimed to investigate the effect of MWCNTs on properties of slag Geopolymeric mortar. Geopolymeric matrices containing different MWCNTs concentrations (0.0, 0.1, 0.2, 0.3 and 0.4 % by weight of the used binder) were synthesized. The Geopolymer mortar composed of aluminosilicate slag to sand (1:2), while the alumino silicate source binder composed of 50% air cooled slag and 50%water cooled slag both passing a sieve of $90{\mu}m$, while the sand passing a sieve of 1 ml. The materials prepared at water/binder ratios in a range of 0.34-0.39% depending on the added MWCNT, whereas the Gelenium Ace-30 superplasticizer used in the ratio of 1.4-2.2% from the total dry weight for better dispersion of MWCNT under sonication for 15 min. Alkaline activation of the Geopolymer mortar was carried by using of 6% NaOH. Curing was performed under temperature of $40^{\circ}C$ and 100% R.H. Results showed that the addition of MWCNTs enhanced the resulting amorphous geopolymer structure with marked decrease in the drying shrinkage as well as water absorption specially when using 0.1% MWCNT, while further increase in MWCNTs results in agglomeration in MWCNT within the matrix and so hinder the propagation of Geopolymerization reaction and negatively affect the formed geopolymer structure.

• Journal of Microbiology and Biotechnology
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• 제26권6호
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• pp.1087-1097
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• 2016

An intracellular lipase from Anoxybacillus flavithermus HBB 134 was purified to 7.4-fold. The molecular mass of the enzyme was found to be about 64 kDa. The maximum activity of the enzyme was at pH 9.0 and 50℃. The enzyme was stable between pH 6.0 and 11.0 at 25℃, 40℃, and 50℃ for 24 h. The K_m and V_max of the enzyme for pNPL substrate were determined as 0.084 mM and 500 U/mg, respectively. Glycerol, sorbitol, and mannitol enhanced the enzyme thermostability. The enzyme was found to be highly stable against acetone, ethyl acetate, and diethyl ether. The presence of PMSF, NBS, DTT and β-mercaptoethanol inhibited the enzyme activity. Hg²⁺, Fe³⁺, Pb²⁺, Al³⁺, and Zn²⁺ strongly inhibited the enzyme whereas Li⁺, Na⁺, K⁺, and NH₄⁺ slightly activated it. At least 60% of the enzyme activity and stability were retained against sodium deoxycholate, sodium taurocholate, n-octyl-β-D-glucopyranoside, and CHAPS. The presence of 1% Triton X-100 caused about 34% increase in the enzyme activity. The enzyme is thought to be a true lipase since it has preferred the long-chain triacylglycerols. The lipase of HBB 134 cleaved triolein at the 1- or 3-position.

• Advances in concrete construction
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• 제15권3호
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• pp.149-159
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• 2023

Water glass (WG) and sodium sulfate (SS) were used to prepare polymeric aluminum chloride residue cement mortar (PACRM) by single and compound blending with polymeric aluminum chloride waste residue, respectively. The structural strength and textural characteristics examinations showed that PACRM consistency increased by incorporating WG, but decreased by incorporating SS. When WG and SS were compounded, the mortar consistency initially rose before falling. The compressive strength of PACRM increased and then decreased as WG was increased. The mechanical properties of PACRM were better enhanced by SS than WG, showing no strength deterioration. The main reason for the improved mechanical properties of polymeric aluminum chloride waste residue in the presence of activators is the increased precipitation of reactive substances, such as C-S-H gels, calcium silica, and Ca(OH)₂. The density of the specimens with PACRM and the degree of aggregation of hydration products were significantly enhanced by generating more hydration products in the mortar. Further, the cracks and pores were significantly reduced, and the matrix structure was continuous and dense at 5% SS doping and 3% compound doping.

• 콘크리트학회논문집
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• 제19권6호
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• pp.667-676
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• 2007

21세기에 들어와 현대의 건설 재료로 대표되는 시멘트 콘크리트는 이산화탄소 발생 등에 의한 지구온난화현상, 대기오염, 환경오염 및 파괴 등에 대한 환경적 문제 및 고성능, 고강도 등에 대한 사회적 문제에 대한 대책마련이 시급한 실정이다. 이에 본 연구에서는 하수슬러지 소각재를 재활용하여 친환경적이며 지속 가능 개발에 적합한 신개념 건설 소재를 개발하여 부족한 천연자원을 대체하고, 폐기물 자원화 기술 확보 및 2차 환경오염 문제를 근본적으로 해결하고자 하였다. 연구 결과, 하수슬러지의 화학성분비는 $SiO_2$와 $Al_2O_3$로 주로 이루어져 있으며, 포졸란 물질의 성분과 유사하였다. 또한 하수슬러지 소각재는 알칼리 활성화에 의해 포졸란반응성을 갖는 경화체로 활용될 수 있음을 알 수 있었으며, 시멘트 콘크리트와 비교하여 적정한 강도 발현의 가능성과 건조수축 등의 유리한 점을 고려할 때, 추후 연구를 통하여 시멘트 대체재로서의 기능을 충분히 발휘할 수 있을 것으로 판단된다.