• Journal of the Korean Ceramic Society
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• v.16 no.3
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• pp.164-168
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• 1979

In the previous paper, it was reported that formation of desirable calcium alunimate(CA) in clinker was considerably affected by sulfur-contaminated alumina which was prone to form a disadvantageous mineral, $C_4A_3S$. In this study, however, sulphate-free alumina cement was made from sulfur-free alumina refined from alunite and corresponding materials. The major minerals in the clinker were identified by X-ray diffraction patterns as calcium aluminate (CA), calcium dialuminate $(CA_2)$ and dicalcium alumino silicate $(C_2AS)$. The formation of CA was more effective with decreasing contents of silica to 2 per cent or less and sulfur in the refined alumina. Physical properties of prepared alumina cement such as setting time, stability and compressive strength were measured. The values were similar to those of commercial alumina cements.

• Cement
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• s.59
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• pp.26-38
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• 1975

본고는 일본 소야전Cement Co.의 중앙연구소주임연구원으로 있는 Hiroshi Uckikawa 박사가 일본의 Ceramics-Japan지(''74.10)에 기고한 것을 번역한 것으로서 그 내용에 의한 목차는 다음과 같다. 즉 근년에 개발된 새로운 cement로서는 1. 속경성 cement 2) 초속경 cement(jet cement, regulated set cement) 2) Alumina cement 3) 초조강 cement 4) 급경 cement 2. 고강도 cement 3. 내구성 cement 1) 내유산균 cement 2) 내화 cement (1) alumina cement 계 (2) barium, strontium 계 cement (3) 인산 aluminium 계 cement 3) 방사선차폐용 cement 4. 팽창 cement 1) alumine 산, 유산 calcium 수화물의 생성에 의한 것 2) 수산화 calcium의 생성에 의한 것 3) 기타 5. 시공성을 개선한 cement (예: 유정용 cement, 도장용 cement) 등이 있다. 머지 않아 우리나라에서도 cement 품종의 다양화가 필연적인 문제로 대두될 것을 생각하여 본번역문이 다소나마 도움이 되기를 바란다.

• The Journal of the Korean dental association
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• v.22 no.4 s.179
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• pp.313-322
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• 1984

This study was designed to observe the marginal leakage of three permanent cements affected by three temporary cements. The temporary cements used in this study were Zinc oxide-eugenol, Non-eugenol, and Calcium hydroxide cements and the permanent cements were Zinc phosphate, Polycarboxylate and Alumina reinforced EBA cements. To measure the dye penetration into permanently cemented zone, the experimental specimens were treated with the temporary cements for a week. An analysis of the data obtained from 120 specimens resulted in the following conclusions: 1. Regardless of the types of the permanent cements used, using Calcium hydroxide cement as temporary cement showed higher marginal leakage than other temporary cements. 2. Using Polycarboxylate cement as permanent cement showed less marginal leakage than other permanent cements. 3. The marginal leakage in zinc phosphate cement was similar to Alumina reinforced EBA cement regardless of the types of the temporary cements.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.199-205
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• 2015

The mechanical and thermal properties of high temperature aluminate cementitious thermal storage materials were investigated in this paper. Alumina cement was used as basic binder and the effect of the replacement of fly ash, silica fume, calcium sulfo-aluminate and graphite for alumina cement was investigated. Experiments were performed to measure mechanical properties including compressive strength before and after thermal cycling, and split tensile strength, and to measure thermal properties including thermal conductivity and specific heat. Test results show that the residual compressive strengths of mixtures with alumina cement only, or alumina cement and silica fume were greater than those of the others. Additionally, the specific heat of mixture with graphite was largest in all the mixtures used in the study. The results of this study could be used to provide realistic information for material properties in thermal energy storage concrete in the future.

• Journal of the Korean Ceramic Society
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• v.27 no.2
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• pp.195-200
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• 1990

For the development of low energy cement, the belite cement clinker of calcium sulphoaluminate ferrite type was synthesized at 130$0^{\circ}C$ and containing C2S, C4A3S as the major minerals along with C3A, C4AF, CS by using limestone, dolomite, clay, iron ore, gypsum and alumina as raw materials. At over 130$0^{\circ}C$, C4A3S was decomposed and thus C3A was increased. When hydrated, this cement was hardened, producing ettringite, CSH, etc.

• Journal of the Korean Ceramic Society
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• v.12 no.4
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• pp.3-8
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• 1975

Hydration processes of the rapid hardening cement clinkers, which were synthesized from domestic alunite for major alumina source, limestone, kaolin and fluorite, were investigated by means of x-ray diffraction analysis, thermal analysis and microscopic observation etc. The clinkers were composed mainly of alite, calcium fluroaluminate (C11A7.CaF2) minerals. While the hydratio processes of the clinkers are altered by concentration of SO3 in the paste, calcium aluminate hydrates such as C4AH13, CAH10 and calcium monosulfate hydrate (C3A.CaSO4.12H2O) are formed at first and then some of them are transformed into ettringite(C3A.3CaSO4.32H2O) within 30~60 min. when the concentration of SO3 in the paste are enough. However the formed ettringite are changed slowly into calcium monosulfate hydrate as the concentration of SO3 become lowered, and the paste is hardened with these close-packed minerals. When the content of SO3 in clinker is so enough, calcium sulfoaluminate hydrates are found without any addition of anhydrite or hemi-hydrite.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.183-184
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• 2023

Considering the actual marine environment construction, this paper monitors the mechanical properties (Flexural, Compressive strength) by exposing alumina cement to seawater. As a result of the experiment, it was confirmed that the strength decreases by about -25% when curing in seawater, but the target strength of the product is met, so it is believed that exposure to the actual marine environment will not be significantly affected.

• Computers and Concrete
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• v.24 no.5
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• pp.453-458
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• 2019

Today, concrete remains the most important, durable, and reliable material that has been used in the construction sector, making it the most commonly used material after water. However, cement continues to exert many negative effects on the environment, including the production of carbon dioxide (CO2), which pollutes the atmosphere. Cement production is costly, and it also consumes energy and natural non- renewable resources, which are critical for sustainability. These factors represent the motivation for researchers to examine the various alternatives that can reduce the effects on the environment, natural resources, and energy consumption and enhance the mechanical properties of concrete. Geopolymer is one alternative that has been investigated; this can be produced using aluminosilicate materials such as low calcium (class F) FA, Ultra-Fine GGBS, and high calcium FA (class C, which are available worldwide as industrial, agricultural byproducts.). It has a high percentage of silica and alumina, which react with alkaline solution (activators). Aluminosilicate gel, which forms as a result of this reaction, is an effective binding material for the concrete. This paper presents an up-to-date review regarding the important engineering properties of geopolymer formed by FA and slag binders; the findings demonstrate that this type of geopolymer could be an adequate alternative to ordinary Portland cement (OPC). Due to the significant positive mechanical properties of slag-FA geopolymer cements and their positive effects on the environment, it represents a material that could potentially be used in the construction industry.

• Clean Technology
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• v.3 no.2
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• pp.87-93
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• 1997

A new process has been developed for nitrate and other salts removals from polluted waters. Alumina cement and calcium oxide served as precipitating agents to remove nitrate with stirring at basic pH. Low content of alumina in the commercialized alumina cements resulted in a increasing in nitrate removal yield. It is found that the compositions of aluminium and calcium are the most important factors in successful nitrate insolubilization. In order to remove high concentration of nitrate in polluted water, multi-stage precipitation was found to be very effective. Sulfate, chloride, and phosphate ions as well as nitrate were also removed by the precipitated reaction. After precipitation, post-treatments including Na2CO3 addition and neutralization with acid alleviated the level of aluminium and calcium in the treated water.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.289-290
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• 2009

In this study, the resistance of calcium aluminate cement (CAC) against chloride-induced corrosion was assessed by testing for the strength, chloride transport, and corrosion behaviour. The study found that the CAC concrete had better performance than ordinary Portalnd cement(OPC) in resisting the corrosion of steel.