• Structural Engineering and Mechanics
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• v.40 no.5
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• pp.595-616
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• 2011

Impact experiments have been carried out on concrete slabs. The first group was traditionally manufactured, densely reinforced concrete targets, and the next were ordinary Portland and calcium aluminate cement based HPSFRC (High performance steel fiber reinforced concrete) and SIFCON (Slurry infiltrated concrete) targets. All specimens were hit by anti-armor tungsten projectiles at a muzzle velocity of over 4 Mach causing destructive perforation. In Part I of this article, production and experimental procedures are described. The first group of specimens were ordinary CEM I 42.5 R cement based targets including only dense reinforcement. In the second and third groups, specimens were produced using CEM I 42.5 R cement and Calcium Aluminate Cement (CAC40) with ordinary reinforcement and steel fibers 2 percent in volume. In the fourth group, SIFCON specimens including 12 percent of steel fibers without reinforcement were tested. A high-speed camera was used to capture impact and residual velocities of the projectile. Sample tests were performed to obtain mechanical properties of the materials. In the companion Part II of this study, numerical investigations and simulations performed will be presented. Few studies exist that examine high-velocity impact effects on CAC40 based HPSFRC targets, so this investigation gives an insight for comparison of their behavior with Portland cement based and SIFCON specimens.

• Journal of the Korean Ceramic Society
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• v.15 no.4
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• pp.199-204
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• 1978

In the present investigation, refined alumina obtained from alunite locally available was used as a aluminous source to synthesize monocalcium aluminate $(CA)_3$ the major mineral constituent of alumina cement. The influence of $SiO_2$ and $Fe_2O_3$ contents on the formation of monocalcium aluminate was studied by X-ray diffraction analysis mainly. About 0.8-1.0 of $Al_2O_3/C_3O$ mol ratio and less than 4 percent of $SiO_2$ were desirable for the effective formation of CA. The small amount of alkali and sulphur contents contained in refined alumina from alunite as the impurities were affected to form $C_4A_3S$ and $C_3S_2$, disadvantageous compounds for the alumina cement, therefore the impurities should be restricted in minimum content as possible.

• Cement
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• s.120
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• pp.24-33
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• 1990

• Journal of Energy Engineering
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• v.27 no.1
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• pp.33-39
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• 2018

In this paper, we reviewed briefly about the barrier materials for the radioactive waste disposal. The primary concept of the radioactive waste disposal is safety. The goal of the radioactive waste management is to assure that the environment is not adversely affected and also public. There are a wide variety of materials are available for the radioactive waste disposal or storage. Among those coal fly ash is one of the significant materials are used as a barrier material. Here we reported, the Calcium sulfo aluminate (CSA) from coal fly ash is effectively suitable for the radioactive waste disposal. This is one of the ways of utilization of waste and manufactured the valuable materials for future indeeds.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.419-427
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• 2017

In order to examine the possibility of practical use of aluminate cement concrete at low-temperature environment with insulation method, an experimental studies on flowability, setting time, freezing temperature, size variation and compressive strength of the mortar at low-temperature were conducted. Compressive strength was increased in use of CSA, aluminate cement with gypsum. Workability and physical properties were improved by using aluminate cement and gypsum. In addition, freezing resistance and physical properties were improved by applying the insulation curing method. Especially, when alumina cement and gypsum were used together, the insulation curing method was more effective in improving the compressive strength.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.68-75
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• 2012

The biogenic corrosion of mortars adopted in sewage repair by sulfuric acid-producing bacteria was considered in this paper. Calcium aluminate cement (CAC) was known to resist microbiologically-induced corrosion significantly better than portland and blended portland cement.In this study, CAC as well portland cement mortars were tested as main binder to evaluate the corrosion resistance by the chemical immersion test. Replacement ratios of CAC were changed as 0, 20, 40, 50, 60% of OPC binder and 0, 2, 4, 6% of EVA(Ethylene Vinyl Acetate) were also adopted to increase properties of CAC repair mortars in sewage application. Setting time, compressive strength, acid resistance and adhesive strength were measured for various experiments. As a results of the experiments, the proper formulation of repair mortars was found at 40% of CAC and 4% of EVA. Finally, the CAC mortars adopted in field sewer pipe and were demonstrated to superior in adhesion and workability.

• Cement Symposium
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• no.32
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• pp.97-102
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• 2005

• Cement Symposium
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• s.37
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• pp.68-74
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• 2010

• Structural Engineering and Mechanics
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• v.40 no.5
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• pp.617-636
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• 2011

We present the numerical implementation, simulation, and validation of the high-velocity impact experiments that have been described in the companion article. In this part, numerical investigations and simulations performed to mimic the tests are presented. The experiments were analyzed by the explicit integration-based software ABAQUS for improved simulations. Targets were modeled with a damaged plasticity model for concrete. Computational results of residual velocity and crater dimensions yielded acceptable results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.4
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• pp.1-9
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• 2020

This study conducted to understand effects of CA (CaAl₂O₄) and CA₂ (CaAl₄O₇) ratio on chloride binding ability and compressive strength and pore structure of cement mortar incorporating mixture of CA and CA₂. The Portland cement based specimens were mixed with the clinkers CA and CA₂, and these calcium aluminate clinker mixture were replaced 0, 5, 10% by weight of cement. After all the test specimens were cured for 28 days under water curing, they were immersed in the distilled water and NaCl solution. As a result, 28 days compressive strength of all specimens was similar, and As the replacement ratio of calcium aluminate clinker in the specimen increased, Friedel's salt production tended to increase. However, it was dependent on the amount of Al₂O₃ in the level of 5% replacement and CA ratio in the level of 10% replacement. Through equilibrium isotherm result, it was also indicated that as replacement ratio of calcium aluminate clinker in cement matrix increased, chloride binding capacity was improved, and chloride penetration was suppressed. In this study, the specimen replaced with 10% of the calcium aluminate clinker mixture (CA 39%, CA₂ 60%) was remarkable to control chloride attack. We figured out necessity to understand optimal CA/CA₂ ratio to effectively apply CA₂ as a sustainable building material by improving the chloride binding ability in Portland cement based system.