• 한국세라믹학회지
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• 제27권5호
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• pp.577-582
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• 1990

The synthesis conditions of fibrous calcium sulfate hemihydrate were investigated by using phosphogypsum and calcium sulfate hemihydrate. The unstable organogel was deposited by adding methanol to the saturated solution with gypsum at ageing temperature, and it was crystallized to fibrous gypsum hemihydrate while methanol was removed by rapid filtrating. In case of using calcium sulfate hemihydrate, fibrous $\beta$-calcium sulfate hemihydrate was formed by adding methanol of 67% to saturated solution at 6$0^{\circ}C$ and ageing for 5 minutes and filtering with suction. Minor components in phosphogypsum did not affect the reaction.

• 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.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.18-19
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• 2017

In this study, hardening characteristics and microstructure of blast furnace slag-cement mortar replaced alpha-calcium sulfate hemihydrate were analyzed. As a result of replacing alpha-calcium sulfate hemihydrate with 0, 10, 20, 30%, it was confirmed that the initial and final setting times are faster than that of blast furnace slag-cement mortar. The compressive strength of the specimens containing alpha-calcium sulfate hemihydrate decreased in the range of 42 ~ 76% at age 28 days compared with blast furnace slag-cement mortar. In the case of replacing the alpha-calcium sulfate hemihydrate, the shrinkage did not occur more rapidly than the cement mortar, but the slope of the strain curve showed a linear behavior. The results of scanning electron microscopy images analysis showed that the formation of ettringite was increased at alpha-calcium sulfate hemihydrate replaced mortar.

• 한국건축시공학회지
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• 제12권6호
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• pp.575-585
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• 2012

The extruded cement panel, which has many advantages as a prefabricated method, has been limited in its application due to its low fire-resistance. However, an extruded cement panel produced by mixing a-hemihydrate gypsum offers dramatically improved fire-resistance and is expected to have wide-ranging applications in the construction sector as an interior material or partition wall between housing units. Sound insulation performance is very important for the partition wall between housing units. In this study, the sound insulation performance of the extruded cement panel produced through the mixture of a-hemihydrate gypsum is reviewed in order to determine its usability for a partition wall between housing units and for interior materials. Through the review it was found that the wall formed using the extruded cement panels produced by mixing the a-hemihydrate gypsum have ★★★ class in sound insulation test, equal or superior compared with the other two types of extruded cement panel walls currently available in the market.

• 한국구조물진단유지관리공학회 논문집
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• 제21권5호
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• pp.117-124
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• 2017

${\alpha}$형 반수석고는 생산방법이 복잡하고, 대량 연속 생산이 곤란하며, 재료 단가가 높기 때문에 건설재료로써 활용범위가 크지 않았으나, 최근 화력발전소의 배연탈황석고를 활용하여 경제적으로 ${\alpha}$형 반수석고를 제조하는 기술이 실용화되고 있다. 이에 본 연구에서는 응결 시작 시간이 빠르고 재령 초기 팽창변형이 발생하는 ${\alpha}$형 반수석고의 특징에 주목하여, ${\alpha}$형 반수석고를 10, 20, 30 wt.% 치환한 보통포틀랜드시멘트 및 고로슬래그시멘트 모르타르를 제조한 후 응결 및 압축강도 특성, 건조수축을 검토하였다. 실험 결과, ${\alpha}$형 반수석고의 치환율이 증가할수록 보통포틀랜드시멘트 모르타르 및 고로슬래그시멘트 모르타르의 초결시간이 빨라지는 경향을 확인할 수 있었다. 또한, 보통포틀랜드시멘트 모르타르와 고로슬래그시멘트 모르타르 모두 ${\alpha}$형 반수석고의 치환율이 증가할수록 압축강도가 저하되는 경향을 보였으며, 보통포틀랜드 시멘트보다 고로슬래그시멘트에서 ${\alpha}$형 반수석고의 압축강도 발현이 유리한 것으로 나타났다. 한편, ${\alpha}$형 반수석고를 치환한 모르타르의 경우 ${\alpha}$형 반수석고의 혼입에 의해 생성된 에트링가이트 침상결정의 성장압에 의해 초기재령에서 수축변형이 저감되는 것을 확인할 수 있었으며, 초기 재령에서 수축변형의 억제 효과는 분명하지만, 재령이 지남에 따라 ${\alpha}$형 반수석고를 치환하지 않은 조건과 변형의 차이는 다시 감소하는 경향을 보였다. 따라서 ${\alpha}$형 반수석고를 모르타르에 적용할 경우 강도는 다소 저하하지만, 응결 촉진 및 수축변형 억제에 큰 효과가 있기 때문에 건설재료로써 활용 가치가 높을 것으로 판단된다.

• 한국건축시공학회지
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• 제19권1호
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• pp.1-7
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• 2019

본 연구에서는 전력구 콘크리트 구조물에서 발생하는 균열저감을 위해 알파형 반수석고를 치환한 콘크리트의 역학적 특성을 평가하였다. 알파형 반수석고의 치환율은 0, 6, 9, 12, 15%로 설정하여, 응결시간, 압축강도, 건조수축을 측정하였으며, 미세구조 및 결정구조의 분석을 실시하였다. 실험 결과, 알파형 반수석고의 치환율이 증가할수록 응결시간이 단축되었으며, 압축강도가 저하되는 경향을 확인하였다. 한편, 알파형 반수석고를 15% 치환할 경우 보통포틀랜드시멘트 콘크리트에 비해 건조수축이 약 60% 저감되는 효과가 나타났다. 따라서, 전력구 콘크리트 구조물에 알파형 반수석고를 치환한 콘크리트를 적용할 경우 균열저감 성능이 향상될 것으로 판단되며, 압축강도의 개선은 필요할 것으로 판단된다.

• 한국건축시공학회지
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• 제12권6호
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• pp.586-595
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• 2012

While the extruded cement panel has many advantages compared to drywall, it has limited applicability in buildings due to its low fire resistance. However, an extruded panel in which the fire resistance has been dramatically enhanced through the addition of a-hemihydrate gypsum is expected to become widely applied as a partition wall or interior material for buildings. To ensure its applicability, certain safety requirements for use, such as the leaning load by residents, the impact by indoor articles, and the fire, need to be taken into consideration. The purpose of this study is to review the impact load resistance, horizontal load resistance, and fire resistance as required safety properties for the partition wall and interior materials of the extruded panel that includes a-hemihydrate gypsum. The results of this study show that the impact load resistance of the extruded panel that includes a-hemihydrate gypsum achieves SD grade for industrial buildings, and the horizontal impact load resistance achieves HD grade for public buildings. In addition, it provides fire-resistance for approximately 7 minutes longer than the existing extruded cement panel. Based on this result, it is confirmed the extruded panel incorporating a-hemihydrate gypsum has adequate safety properties for use as partition wall or interior material.

• 한국세라믹학회지
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• 제25권5호
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• pp.449-454
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• 1988

The effects of salts which was used as a catalysis in formation of $\alpha$-calciumusulfate hemihydrate from dicalcium sulfate hydrate were investigated on the hydration of $\alpha$-calciumsulfate hemihydrate. The hydration of $\alpha$-calciumsulfate hemihydrate was studied by the measurements of crystalline water, heat evolution. Also the hydrates were analyzed by XRD, DSC and SEM. The promotive effect each salts on the hydration was as follows: NaCl>NH4Cl>NaNO3>NH4NO3, and the hydration rate was accelerated with concentration of salts. The effect of Al2(SO4)3 and potassium sodium tartrate on the hydration was slmilar to water, whereas sodium succinate and gelatin retarded the hydration in comparision with water. These salts affected the hydration time but total heat evoution was similar.

• 한국세라믹학회지
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• 제24권4호
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• pp.343-348
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• 1987

The effects of salts such as aluminum sulfate as inorganic salt(2-4%), and sodium salts of citrate, tartrate, succinate, potassium tartrate and gelatin as organic salts(0.1%) on the formation of ${\alpha}$-calcium sulfate hemihydrate from by-product gypsum of phosphoric acid process under hydrothermal condition at 123$^{\circ}C$ and 133$^{\circ}C$ were investigated. Aluminum sulfate solution exhibited the catalystic effected on the crystallization of ${\alpha}$-calcium sulfate hemihydrate of which was assumed in the prismatic form, and organic salts solution exhibited little effect on the catalystic action to the crystallization, than inorganic salts. In the acidic solution with sulfuric acid(pH=2), needle like crystal of calcium sulfate hemihydrate was obtained. Hydrothermal process with aluminum sulfate solution also showed certain amounts of impurity removal such as phosphorus penataoxide from calcium sulfate hemihydrate.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.109-110
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• 2011

Gypsum is an important building material used to provide fire resistance to constructions by reducing their temperature rises. As the hardened gypsum is exposed to fire, evaporation of both the free water and the chemical bond water is easier than that in the cement extruding panel. The purpose of this study is to investigate the utilizability of alpha-hemihydrate gypsum to prevent spalling failure of cement extruding panel exposed to fire. This paper reports the fire-resistance property of a controled general cement extruding panel(C100), and gypsum-cement extruding panels(C50A50, A100) according to replacement ratio of alpha-hemihydrate gypsum. As a results, it is found that A100 and C50A50 are more effective to prevent the explosive spalling failure under standard fire condition than C100.