• Title, Summary, Keyword: gypsum

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Effect of gypsum content on the properties of PVC/Gypsum polymer blend material (PVC/Gypsum 복합체에서 Gypsum 의 영향)

  • N. V. Gian;Thai Hoan;Kim, M. Y.
    • Proceedings of the Korean Society For Composite Materials Conference
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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.

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Hydration-Setting Property of β-Hemihydrate Gypsum by Adding of Accelerator and Ground Gypsum (경화촉진제 및 마쇄 이수석고 첨가에 의한 β-반수석고의 수화응결 특성)

  • Choi, Jeong-Bong;Kim, Jong-Pal
    • Applied Chemistry for Engineering
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    • v.8 no.5
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    • pp.822-829
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    • 1997
  • When $Al_2(SO_4)_3$ as an accelerator was added to $\beta$-hemihydrate gypsum, the setting time, mobility and compressive strength properties of $\beta$-hemihydrate gypsum were examined with the adding of two types grounded gypsum crushed by ball mill. By 15wt% adding of 7% $Al_2(SO_4)_3$ dilute solution, the setting time of $\beta$-hemihydrate gypsum was sharply accelerated than that of non-added $\beta$-hemihydrate gypsum. When ground phospho gypsum(PG) and chemical gypsum(CG) were added to $\beta$-hemihydrate gypsum, the initial and final setting time of $\beta$-hemihydrate gypsum were accelerated markedly with the increasing of grinding time and added amount of ground phospho gypsum. Especially, this trend largely presented when ground phospho gypsum was added to $\beta$-hemihydrate gypsum. The compressive strength of $\beta$-hemihydrate gypsum added by ground phospho and chemical gypsum was largely increased at initial curing time such as 1, 3 days. Particularly, the compressive strength of $\beta$-hemihydrate gypsum added by ground phospho gypsum was increased by 15~20% than that of ground chemical gypsum.

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Study for the quality and the herbalogical Gypsum (석고(石膏)의 본초고증(本草考證) 및 좌용석고(左用石膏)의 품질(品質))

  • Lee Jang-Cheon
    • Herbal Formula Science
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    • v.11 no.2
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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.

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Evaluate Changes in Soil Chemical Properties Following FGD-Gypsum Application

  • Lee, Yong-Bok;Bigham, Jerry M.;Kim, Pil-Joo
    • Korean Journal of Environmental Agriculture
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    • v.26 no.4
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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.

Investigation on Properties of Cement Mortar Using Heat Treated Flue Gas Desulfurization Gypsum (열처리된 배연탈황석고를 혼입한 시멘트 모르타르의 물성 연구)

  • Chung, Chul-Woo;Lee, Yong-Mu;Kim, Ji-Hyun;Kim, Young-Su
    • Journal of the Korea Institute of Building Construction
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    • v.16 no.6
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    • pp.497-503
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    • 2016
  • Flue gas desulfurization gypsum is produced from emission process of fossil fuel power plant to remove sulfur dioxide ($SO_2$) from exhaust gas. Production of flue gas desulfurization gypsum in Republic of Korea has been increasing due to the enforced regulations by government agency. Since flue gas desulfurization gypsum has characteristic that is similar to that of natural gypsum, there is a strong possibility for flue gas desulfurization gypsum to replace the role of natural gypsum. However, consumption of such material is still limited, only used for agricultural purposes or to make gypsum boards, it is necessary to expand the use of this material more aggressively. In this research, the chemical and mineralogical properties of flue gas desulfurization gypsum were investigated, and flue gas desulfurization gypsum with heat treatment was used to make cement paste. According to the results, it was found that flue gas desulfurization gypsum used in this experiment was a very high purity gypsum, and shown to have similar property to that of natural gypsum. Heat treating flue gas desulfurization gypsum above $100^{\circ}C$ was shown to bring beneficial effect on both compressive strength and drying shrinkage

Recovery and Refining Process of Gypsum from Waste Plaster Board

  • Song, Young-Jun;Hiroki Yotsumoto
    • Resources Recycling
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    • v.10 no.6
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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.

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Capping Treatment for the Reduction of Phosphorus Release from Contaminated Sediments of Lakes (호소퇴적물로부터 인 용출 저감을 위한 Capping 처리)

  • Kim, Seog-Ku;Lee, Mi-Kyung;Ahn, Jae-Hwan;Yun, Sang-Leen;Kim, So-Jung
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.4
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    • pp.438-446
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    • 2006
  • A lab-scale batch test was conducted to develop capping materials to reduce the sediment phosphorus in the stagnant water zone of Gyeongancheon in Paldang Lake. The mean grain size(Mz) of sediment in the investigated area was 7.7 ${\phi}$, which is very fine, and the contents of organic carbon($C_{org}$) was 2.4%, which is very high. For the phosphorous release experiment to select the optimal capping material, sand layer, powder-gypsum($CaSO_4{\cdot}2H_2O$), granule-gypsum, complex layer(gypsum+sand) and the control were compared and evaluated in the 150 L reactor for 45 days. In case of the capping with the sand, it was found that the phosphorous from the sediment could be reduced by around 50%. However, it was found that this caused the reduction of the dissolved oxygen in the water column(by less than 3 mg/L) due to the resuspension of sediment and the organic matter decomposition that comes from the generation of $CH_4$ gas in the 1 cm of the sand layer. Therefore, it is likely that the sand layer has to be thickener in case of the sand capping. Powder-gypsum and granule-Gypsum reduced phosphorous release by more than 80%. However, the concentration of ${SO_4}^{2-}$ in the water column increased, making it difficult to apply it to the drinking water protection zone. We developed Fe-Gypsum and $SiO_2$-gypsum materials to reduce the solubility of ${SO_4}^{2-}$. Powder-Gypsum creates the interception film that does not have any aperture on the sediment layer when it is combined with the water. However phosphorous release caused by the generation of $CH_4$ gas may happen at a time when the gypsum layer has the crack. Capping through the complex layer(granule-Gypsum+sand(1 cm)) found to be suitable for the drinking water protection zone because it was effective to prevent phosphorus release. Moreover, this leads to the lower solubility from the concentration of ${SO_4}^{2-}$ into the water column than the powder-Gypsum and granule-Gypsum. The addition of gypsum($CaSO_4{\cdot}2H_2O$) into the sediment can reduce the progress of methanogensis because fast early diagenesis and sufficient supply of ${SO_4}^{2-}$ to the sediment, stimulate the SRB(sulfate reducing bacteria) highly.

Review on the heat storage performance and air pollutant adsorption properties of gypsum board according to the additives (석고보드의 첨가제에 따른 오염물질 흡착 및 축열 성능에 대한 고찰)

  • Seo, Hyun Jeong;Jeong, Su-Gwang;Lim, Jae-Han;Kim, Sumin
    • Journal of the Korean Solar Energy Society
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    • v.35 no.1
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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.

Effect of Surface Modifying Agents Towards Enhancing Performance of Waste Gypsum Based PBAT Composite

  • Kong, Tae Woong;Kim, In Tae;Sinha, Tridib Kumar;Moon, Junho;Kim, Dong Ho;Kim, Inseon;Na, Kwangyong;Kim, Min-Woo;Kim, Hye-Lin;Hyeong, Taegyeong;Oh, Jeong Seok
    • Elastomers and Composites
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    • v.55 no.4
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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.

Initial Strength Characteristics of Cementitious Gypsum-Containing Coal Gasification Slag Powder Replacement Cement Mortar (석고 혼입 석탄가스화 슬래그 미분말 치환 시멘트 모르타르의 초기강도 특성)

  • Cho, Hyeon-Seo;Kim, Min-Hyouck;Lee, Gun-Cheol;Cho, Do-Young
    • Proceedings of the Korean Institute of Building Construction Conference
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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.

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