• 한국세라믹학회지
• /
• 제44권9호
• /
• pp.465-470
• /
• 2007

This paper presents an experimental study of the sulfate resistance of mortars and pastes exposed to sodium sulfate solutions up to one year. In order to check deterioration modes due to sulfate attack, the sodium sulfate solution was varied at three concentration steps (3,380, 10,140 and 33,800 ppm of $SO_4^{2-}$ ions), and maintained at ambient temperature. The tests include a visual examination, expansion and compressive strength loss measurements as well as x-ray diffraction tests. The experimental data indicated that the use of cement with a low $C_3A$ content and low silicate ratio has a beneficial effect on the sulfate attack of mortars. In contrast, the mortars with a high $C_3A$ content and high silicate ratio became severely degraded due to the formation of ettringite, gypsum and/or thaumasite in the cement matrix.

• 콘크리트학회논문집
• /
• 제21권4호
• /
• pp.441-447
• /
• 2009

황산염침식을 방지하기 위하여 포틀랜드시멘트 중의 황산염침식 저항성이 우수한 시멘트를 선정하기 위한 연구의 일환으로 황산나트륨 용액에 360일간 침지한 후 모르타르의 역학적 특성 및 기기분석을 통하여 침식 특성을 평 가한 결과, 외관조사, 강도감소 및 길이변화에 따른 성능저하 순서는 보통 포틀랜드시멘트 >내황산염 포틀랜드시멘트 > 저열 포틀랜드시멘트 순으로 나타났다. 포틀랜드시멘트의 주요 반응생성물은 Calcite 피크 이외에도 황산염과의 반응으 로 인한 Gypsum, 에트린자이트 및 Thaumasite로 확인되었다. 포틀랜드시멘트의 경우 시멘트의 조성광물 비에 따라 성 능저하 형태가 상이하게 나타났다. 특히, C3A량과 칼슘실리케이트비가 가장 적은 저열 포틀랜드시멘트가 황산염침식 저 항성에 매우 우수한 것으로 확인되었다.

• 한국가구학회지
• /
• 제19권1호
• /
• pp.83-90
• /
• 2008

Gypsum-wood composites were made by introducing inorganic substances into wood using calcium chloride, first treating solution, and sodium sulfate, secondary treating solution, by double diffusion process under atmospheric pressure at room temperature. The process conducted as follows: water saturated specimens were soaked in calcium chloride solutions at several concentration. Then the specimens were soaked further in saturated sodium sulfate solution, and they were leached in flowing tap water for 24h. To attain sufficient weight percent gain (WPG) values, the suitable concentration of calcium chloride and soaking time in saturated sodium sulfate solution were 20% and 48h, respectively. Inorganic substances were produced mainly in the lumina of tracheides. It was made sure that these substances were dihydrate gypsum($CaSO_4$ $2H_2O$) by X -ray microanalysis (SEM-EDX). The composites had good fire resistance due to low heat transfer rate of gypsum formed in wood. However, the composites had little decay resistances, because they showed high weight losses by test fungi attacks.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
• /
• pp.27-32
• /
• 2002

In this research influences of type and concentration of alkali activator and curing condition on the hydration, and properties of alkali activated blast furnace slag(AAS) concrete were investigated. Sodium carbonate and sulfate were used as alkali activators and their concentration were 4~10 weight percent with Na$_2$O equivalent to binder. The curing conditions were standard curing using 23$^{\circ}C$ water and activated curing chamber at $65^{\circ}C$. Results show that in case of sodium carbonate addition high early strengths were gained by activation of early hydration, but later strength gained was slight. On the other side sodium sulfate strengths were continuously increased with adding amount and ages. Steam curing activated early hydration so that early strengths were improved but later strengths were similar to standard curing. The strength reduction of AAS mortar with sodium sulfate was less than OPC mortar in 5% sulfuric acid solution so that AAS concrete can be useful for acid-resistance concrete.

• Computers and Concrete
• /
• 제19권2호
• /
• pp.143-152
• /
• 2017

This paper has numerically investigated the changes of loading-induced stress in concrete with the corrosion time in the sulfate-containing environment. Firstly, based on Fick's law and reaction kinetics, a diffusion-reaction equation of sulfate ion in concrete is proposed, and it is numerically solved to obtain the spatial and temporal distribution of sulfate ion concentration in concrete by the finite difference method. Secondly, by fitting the existed experimental data of concrete in sodium sulfate solutions, the chemical damage of concrete associated with sulfate ion concentration and corrosion time is quantitatively presented. Thirdly, depending on the plastic-damage mechanics, while considering the influence of sulfate attack on concrete properties, a simplified chemo-mechanical damage model, with stress-based plasticity and strain-driven damage, for concrete under axial loading and sulfate attack is determined by introducing the chemical damage degree. Finally, an axially compressed concrete prism immersed into the sodium sulfate solution is regarded as an object to investigate the time-varying stress in concrete subjected to the couplings of axial loading and sulfate attack.

• 한국세라믹학회지
• /
• 제25권3호
• /
• pp.300-306
• /
• 1988

The catalytic effect of salts on formation of ${\alpha}$-calcium sulfate hemihydrate under water vapor at atmospheric pressure was studied and the formation of q-calcium sulfate hemilydrate from by-product gypsum of phosphoric acid process was investigated. The order of catalytic effect of salts are as follow: Ammonium chloride>Sodium succinate>Calcium chloride>Sodium tartrate>Magnesium chloride The prismatic crystals was formed when ammonium chloride, calcium chloride and magnesium chloride was added, whereas the needle crystals was formed when sodium tartrate was added. Ammonium chlorideis most successful in catalytic effects in formation of ${\alpha}$-calcium sulfate hermihydrate for the by-product gypsum of phosphoric acid process.

• 한국식품영양학회지
• /
• 제23권4호
• /
• pp.435-439
• /
• 2010

The aim of this study was to evaluate the anti-inlfammatory effects of Glycyrrhiza glabra Linne extract on ulcerative colitis induced by 3% dextran sulfate sodium in mice. The experimental animals were divided into six groups: control(normal), DSS-induced colitis(control), 1 mg/kg, 10 mg/kg, and 100 mg/kg of Glycyrrhiza glabra Linne extract, and 150 mg/kg 5-aminosalicylic acid(5-ASA)(positive control). We evaluated the pathological disease activity index(DAI), change in weight, colon mucosa damage and myeloperoxidase(MPO) in colon mucosa. Treatment with 10 mg/kg and 100 mg/kg of Glycyrrhiza glabra Linne extract led to significant loss of body weight, the decrease of MPO activity and clinical symptoms such as DAI and histological change. In particular, 100 mg/kg Glycyrrhiza glabra Linne extract led to markedly greater improvement than 150 mg/kg 5-ASA treatment. These results suggest that Glycyrrhiza glabra mediated anti-inflammatory action on colorectal sites may be a useful therapeutic approach to ulcerative colitis.

• 생약학회지
• /
• 제43권1호
• /
• pp.22-26
• /
• 2012

The aim of this study was to evaluate the anti-inlfammatory effect of the extract of Zanthoxylum schinifolium on ulcerative colitis induced by 3% dextran sulfate sodium in the rat. The experiment animals were divided into six groups: control (normal), DDS-induced colitis, 1 mg/kg, 15 mg/kg and 150 mg/kg of the extract of Z. schinifolium and 150 mg/kg of 5-aminosalicylic acid (5-ASA) as comparative drug. Anti-ulcerative colitis effect was evaluated pathologically by disease activity index (DAI), the change of weight and myeloperoxidase (MPO) in colon mucosa. Treatment with 15 mg/kg and 150 mg/kg of the extract of Z. schinifolium significantly improved the gain of body weight and DAI as clinical symptoms, and reduced MPO and $PGE_2$ level as biochemical index. Especially, 150 mg/kg of the extract of Z. schinifolium showed markedly more improvement than the same dose of 5-ASA in all kind of index such as MPO, $PGE_2$ and DAI. These results suggest that Z. schinifolium mediated anti-inflammatory action on colorectal sites may be a useful therapeutic approach to ulcerative colitis.

• 한국가구학회지
• /
• 제19권5호
• /
• pp.358-364
• /
• 2008

Wood-inorganic material composite (WIC) was prepared by impregnating wood with copper sulfate ($CuSO_4\;5H_2O$) solution and by immersed wood in sodium carbonate($Na_2CO_3$) solution in order to introduce insoluble copper compounds {copper carbonate hydroxide, $CuCO_3\;Cu(OH)_2$} into the wood to give fungicidal effects in treated-wood. The weight percent gains (WPGs) of treated wood reached maximum value by impregnation of 20% copper sulfate solution and immersion in about 15% sodium carbonate solution for 24 hrs. Inorganic substances were present mainly in the lumina and cross-field pitting of tracheides. These substances were proved to be the insoluble copper carbonate hydroxide against water by the energy dispersive X-ray analyzer in conjunction with a scanning electron microscope (SEM-EDXA). The treated specimens showed high preservative effectiveness because the weight losses were hardly occurred by the fungi degradation test.

• 대한화장품학회지
• /
• 제8권1호
• /
• pp.1-2
• /
• 1980