• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.25-28
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• 2005

This study shows the early quality improvement of concrete with calcium sulfa aluminate(CSA). For the properties of slump, plain concrete incorporating BS $35\%$ and UP $15\%$ resulted in high fluidity compared with OPC without any admixture. As displacement ratio of CSA increased. the fluidity decreased. The fluidity also declined with setting time. Increase of incorporation ratio of CSA declined bleeding and accelerated setting time. Importantly, using more CSA helped to improve early compressive strength and decrease drying shrinkage. In term of water curing, drying shrinkage hardly ever occurred.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.6
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• pp.115-121
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• 2000

The purpose of this research is to investigate properties and field application of non-shrinkage high strength concrete containing expansive additive. Before the field applications, several basic laboratory test are performed to evaluate the characteristics of air content, workability and strength of the concrete using calcium sulfa aluminate(CSA) expansive additive. As a result, high strength concrete using CSA expansive additive show similar workability and compressive strength to that normal concrete, and the optimum replacement ratio of them is obtained by 10% CSA expansive additive. Accordingly, it can be concluded that the use of CSA expansive additive is effective to prevent shrinkage crack and to achieve volume stability of concrete structure.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.203-207
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• 2005

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.97-101
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• 1996

In this paper, We have studied internal quality incluiding chemical compositions, microscopic structrue and nonmetalic inclusion of test materials. We have analyzed dynamic characteristics of cutting resistence including tensile strength value, hardeness value, impact value etcs. We have compared chip treatments of test materials. In analyzing internal quality, all of test materials have typical ferrite+pearlite structure. But, nonmetallic inclusion have oxide and sulfide inclusion in medium carbon steels, mainly sulfide inclusion is existed in S-free cutting steels. In Ca+S-free cutting steels, calcium aluminate and sulfide complex inclusion, had low-melting points, as deformation of sulfide and oxide inclusion is existed. machining characteristics, cutting resistence is maximum in Ca+S-free cutting steels, minimum in medium carbon steels. Chip treatements are excellent in S-free cutting steels, similar to the Ca+S free cutting steels and medium carbon steels.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.154-165
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• 1996

As II-anhydrite reacts with C3A(aluminate), C4AF(ferrite) at initial hydration of cement and assists the hydrolysis of C3S(calcium silicate), the production rate of ettringite(3C3A.3CaSO4.32H2O) and C-S-H gel was acclerated. It was known that compressive strength of cement concrete improved due to the effect of II-anhydrite. For the checking these effects of II-anhydrite, the fluidity and compressive strength of cementmortar admixed with II-anhydrite and pozollanic fine powders were investigated. By means of SEM analysis, the surface structure of mortar with the condition of steam curing at curing days=28 was investigated. As a result of this experiment, it was examined that II-anhydrite had an increase on the fluidity of cementpaste and compressive strength of mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.397-400
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• 2005

This study is a result that, in order to improve the early stage strength of fly ash, the calciumsulfoaluminate in which the generation of ettringite was very active in the early stage was substituted by some amount, and then the effect on the early stage was analyzed. when fly ash was substituted by 30$\%$, the strength dropped by maximum 54 $\%$ in the 3rd day of aging, compared to the cement mixture, but when CSA was substituted by 8 $\%$ in the fly ash amount, the strength improved at the 86 percent level of cement, it is suggested as an economical and effective method to improve the early-stage strength that CSA should be mixed by 8$\%$ compared to the fly ash amount used

• Journal of the Korean Society for Precision Engineering
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• v.14 no.7
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• pp.22-28
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• 1997

In this paper, We have studied internal quality incluiding chemical compositions, microscopic structure and nonmetalic inclusion of test material. We have analyzed dynamic characteristics of cutting resistence and compared chip treatment of the test material. In analyzing internal quality, all of the test material have typical ferrite+pearlite structure. But, nonmetallic inclusion has oxide and sulfide inclusion has oxide and sulfide inclusion in medium carbon steel, mainly sulfide inclusion is existed in S-free cutting steel. In Ca+S-free cutting steel, calcium aluminate and sulfide complex inclusion, had low-melting point, as deformation of sulfide and oxide inclusion is existed. Machining characteristics, cutting resistence is maximum in medium carbon steel. Chip treatement are excellent in S-free cutting steel, similar to the Ca+S free cutting steel and medium carbon steel.

• 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.

• Journal of the Korea Institute of Building Construction
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• v.19 no.4
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• pp.299-306
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• 2019

In general, repair mortar is used to rehabilitate underground communities, but difficulties are encountered in the execution of long-term construction due to spatial co-operatives. In this study, the engineering properties of repair mortar according to the curing condition and accelerator type were reviewed. The results showed that the aluminate, alkali-free and calcium-aluminate precipitates in the water curing conditions showed higher compressive strength at the beginning of age than mortar specimens under air curing conditions, and increased. Especially in CA and AF test specimen with cement mineral quick setting, a large amount of ettringite products were observed compared with AL, thus reducing the pore volume and increasing the strength of the compound by micro-filling effect were found.