• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.221-224
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• 2003

Polyvinyl chloride (PVC)/gypsum Polymer blend materials were prepared by melt blending of PVC with gypsum and additives. Effect of gypsum content on the properties of PVC/gypsum Polymer blend material was studied by investigating physico-mechanical properties, thermal properties and morphology development. It was found that the replacement of gypsum for methylene-butadiene-sarene (MBS) component in PVC/gypsum polymer blend material enhanced the tensile strength, but gradually decreased its impact strength. Besides, with the increase of gypsum content, the elongation at break of material gradually decreased. The Presence of the different gypsum contents made a shift of g1ass transition temperature and increased the thermal stability as well as the processing temperature range of polymer blends. The observation of morphology, the results of the physico-mechanical properties and thermal properties proved simultaneously that PVC/gypsum Polymer blend material with the gypsum content of 22.56 wt.% reached the optimum results among five kinds of PVC/gypsum Polymer blend materials investigated.

• 공업화학
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• 제8권5호
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• pp.822-829
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• 1997

석고의 경화촉진제로 $Al_2(SO_4)_3$을 첨가하고 ball mill로 분쇄한 2종류의 이수석고(인산 이수석고, 화학이수석고)의 첨가량에 따른 $\beta$-반수석고의 수화응결 및 유동성, 압축강도, 수화상태등에 미치는 영향을 파악하였다. 7%로 희석한 $Al_2(SO_4)_3$를 $\beta$-반수석고에 15wt% 첨가시 수화응결은 무첨가시보다 초결 및 종결시간이 크게 단축되었다. 마쇄인산 이수석고 및 화학이수석고의 첨가시 수화응결은 인산 이수석고의 분쇄시간 및 첨가량 증가에 따라 초결 및 종결시간이 현저히 단축되었으며 특히, 마쇄 인산이수석고의 첨가에 의한 효과가 더 크게 나타났다. 마쇄인산 이수석고와 화학 이수석고가 첨가된 $\beta$-반수석고의 압축강도는 1, 3일의 초기 재령에서 크게 증진되었고 특히, 화학 이수석고에 비하여 마쇄인산 이수석고의 첨가로 $\beta$-반수석고 경화체의 초기 압축강도가 15~20% 증가되었다.

• 대한한의학방제학회지
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• 제11권2호
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• pp.61-82
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• 2003

Objectives: This study has been done to make sure the Gypsum's standardization in medical use. Gypsum has a quality for removing pathogenic heat from the stomach meridian function and headache. Methods: I studied the herbalogical Gypsum and compared its' compositions and character before and after high temperature burning. Results: Gypsum and Lishi(理石) are the sulfate which is made of $CaSO_4{\cdot}2H_2O$, Feldspar is a Calcite, Hanshuishi(寒水石) and Ningshuishi(凝水石) are not a Gypsum but a Magnesium Sulfate($MgSO_4$) and Kalium Sulfate($K_2SO_4$). Conclusion: Real Gypsum is supposed to be Yiong cheng${\setminus}$(應城) Gypsum. Chemical edible Gypsum isn't appropriated to be used in medicine.

• 한국환경농학회지
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• 제26권4호
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• pp.294-299
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• 2007

Natural gypsum has been used as a soil amendment in the United States. However, flue gas desulfurization (FGD)-gypsum has not traditionally been used for agricultural purpose although it has potential benefit as a soil amendment. To expand use of FGD-gypsum for agricultural purpose, the effect of FGD-gypsum on soil chemical properties was investigated in the field scales. Application rates for this study were 0 (control), 1.1, and 2.2 Mg ha-1 of FGD-gypsum. After two year application, the soil samples were taken to 110 cm depth and sub-sampled at 10 cm intervals. The heavy metal contents in FGD-gypsum were lower than ceiling levels allowed by regulations for land-applied biosolids. Soil pH was not largely affected by FGD-gypsum application. Although degree of calcium (Ca) saturation in surface horizons increases only slightly with respect to the control, there is a clear decrease in exchangeable aluminum (Al). FGD-gypsum clearly increases the soil electrical conductivity (EC) with increasing application rate. Water-soluble Ca and sulfate is increased with FGD-gypsum application and these ions moved to a depth of at least 80 cm after only 2 years. We conclude that surface application of FGD-gypsum can mitigate toxicity of Al and deficiency of Ca in subsoil of acid soil.

• 자원리싸이클링
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• 제10권6호
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• pp.43-52
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• 2001

This study was conducted to obtain granular crystalline gypsum that can be used as raw material for Plaster boards or cements from waste Plaster board. Gypsum could be Preferentially disintegrated to gypsum needle in $10\mu\textrm{m}$ or less size by hydration after the dehydration of crushed waste Plaster board. The finer the gypsum needle, it is easier to remove coarse impurities and to recover the gypsum needle. The optimum conditions for obtain the finer gypsum size were dehydration rate of 75~85%, solid concentration at hydration of 10~15%, agitation speed of 250~400 rpm, crushing size before dehydration of 2 cm or less. Gypsum of 98.21% grade was recovered with 99.0% yield as the undersize of 325 mesh wet screening followed by the dehydration-hydration process performed at the conditions of dehydration rate of 80%, solid concentration at hydration of 15%, agitation speed of 300 rpm, crushing size before dehydration of 2 cm or less. After the recrystallization of recovered gypsum, Plate-like gypsum of $151\mu\textrm{m}$ size with 99.49% grade was obtained as the oversize of 270 mesh in a wet screening.

• 대한환경공학회지
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• 제28권4호
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• pp.438-446
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• 2006

팔당호 경안천 하류 정체수역에서 퇴적물 인 용출 저감을 위한 capping 소재를 개발하고자 실험실 규모의 batch test를 수행하였다. 조사지역 퇴적물 평균 입도는 7.7 ${\phi}$로 매우 세립하고, 유기탄소 함량은 2.4%로 매우 높게 나타났다. 최적의 capping 소재 선정을 위한 인 용출 실험을 위해 150 L 반응기 5개에 모래층, powder-gypsum($CaSO_4{\cdot}2H_2O$), granule-gypsum, 복합층(gypsum+sand)로 capping을 한 경우와 control을 45일간 비교 평가하였다. 모래로 capping할 경우, 퇴적물로부터 용출되는 인을 약 50% 차단 가능한 것으로 나타났다. 그러나 모래층 1 cm로는 $CH_4$ gas 발생으로 인한 퇴적물의 재부유와 유기물 분해에 의한 수층 용존산소 감소(3 mg/L 이하)를 초래하는 것으로 나타났다. 따라서 모래로 capping을 할 경우에는 모래층이 더 높아져야 할 것으로 판단된다. powder-Gypsum과 granule-Gypsum은 80% 이상의 인 용출 저감 효과를 보였으나 수층 ${SO_4}^{2-}$ 농도가 증가되어 상수원보호구역에 적용하기 어려운 것으로 나타났다. 따라서 ${SO_4}^{2-}$의 용해도를 감소시키기 위해 Fe-Gypsum, $SiO_2$-gypsum 소재를 개발하였다. powder-Gypsum은 물과 결합시 경화되어 퇴적물 층위에 공극이 전혀 없는 차단막을 만들기 때문에 gypsum 층에 crack이 생길 경우, $CH_4$ gas 발생으로 인한 인 용출이 한꺼번에 일어날 수 있다. 복합층(granule-Gypsum+sand(1 cm))으로 capping을 할 경우, 인 용출 차단 효과가 높을 뿐만 아니라, ${SO_4}^{2-}$ 농도 역시 powder-Gypsum, granule-Gypsum 보다 수층으로 용출이 적어 상수원보호구역에 적합한 것으로 나타났다. Gypsum으로 capping을 할 경우, 빠른 초기속성작용(early diagenesis)과 ${SO_4}^{2-}$ 농도가 퇴적물에 충분히 공급되어 SRB(sulfate reducing bacteria)의 활성이 높아져 methanogensis의 진행을 저하시킬 수 있는 것으로 나타났다.

• 한국태양에너지학회 논문집
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• 제35권1호
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• pp.97-106
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• 2015

Gypsum board is easy to manufacture of a variety of forms and has stable mechanical properties and thermal properties. And gypsum boards are widely used to the walls and ceiling of the building as the interior building materials. The studies about technology of applying the various features in the gypsum board with additives are being actively investigated. Development methods for enhancing performance of the gypsum board using additives are largely divided into two categories. The first case is functional gypsum board that is to improve the moisture absorption and moisture-proof properties. Also studies of adsorption and decomposition of indoor air pollutants of the gypsum board using porous materials as an additive are being actively investigated. Another case is applying thermal storage materials which gives the heat storage performance to gypsum board. In this paper, we would like to introduce the various cases of gypsum board applied various additives.

• Elastomers and Composites
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• 제55권4호
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• pp.347-353
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• 2020

Stearic acid (SA), polyethylene glycol (PEG), and malic acid (MA) have been used to modify the surface of waste gypsum to develop corresponding poly (butylene adipate-co-terephthalate) (PBAT) composites. According to the mechanical properties, MA-treated gypsum (MA-gypsum) showed the best performance, whereas SA-gypsum showed the worst performance. In contrast to SA and PEG (having -COOH and -OH as polar functional groups, respectively), the presence of both -OH and -COOH in MA is responsible for the superior surface treatment of gypsum and its better dispersion in the polymer matrix (as revealed by FE-SEM analyses). The presence of long aliphatic chain in SA is supposed to inhibit the dispersion of SA-gypsum. Further, the performance of MA-gypsum/PBAT was enhanced by adding polylactic acid (PLA). The maximum optimized contents of MA-gypsum and PLA are 20 and 7.5 wt% for developing a high-performance PBAT composite.

• 한국토양비료학회지
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• 제47권5호
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• pp.340-344
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• 2014

Compost and gypsum can be used to ameliorate soil physicochemical properties in reclaimed tidal lands as an organic and inorganic amendment, respectively. To evaluate effects of compost and gypsum on soil water movement and retention as a soil physical property, we measured the soil's saturated hydraulic conductivity and field capacity after treating the soil collected in a reclaimed tidal land with compost and gypsum. Saturated hydraulic conductivity of soil increased when compost was applied at the conventional application rate of $30Mg\;ha^{-1}$. However, the further application of compost insignificantly (P > 0.05) increased saturated hydraulic conductivity. On the other hand, additional gypsum application significantly increased soil saturated hydraulic conductivity while it decreased soil field capacity, implying the possible effect of gypsum on flocculating soil colloidal particles. The results in this study suggested that compost and gypsum can be used to improve hydrological properties of reclaimed tidal lands through increasing soil water retention and movement, respectively.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.207-208
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• 2019

In this study, compressive strength was measured to evaluate the initial strength of cement mortar substituted with coal gasification slag containing desulfurized gypsum, and the reactivity of desulfurized gypsum was confirmed. In order to improve the reactivity, 2% gypsum mixed type and gypsum unfedged type specimens were fabricated and the influence of desulfurization gypsum on compressive strength of coal gasification slag and blast furnace slag fine powder replacement cement mortar was compared and confirmed. As a result of the experiment, it was confirmed that the initial compressive strength of the specimen containing the desulfurized gypsum was improved at the initial stage.