• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.145-152
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• 2003

This paper develops a relatively comprehensive and sophisticated constitutive model of concrete for finite element analysis of concrete structures. The present model accounts for the hydrostatic pressure sensitivity and Lode angle dependence behavior of concrete, not only in its strength criterion, but also in its hardening characteristics. The implementation is carried out through incorporating the developed concrete model in User Subroutine Material(UMAT) of the general-purpose FE program ABAQUS(v.5.8). It is found that the model can sufficiently predict the hardening as well as the softening behaviour of concrete under high confining pressure.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.41-46
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• 2000

In recently, though the development of antiwashout admixture, if's possible to construct in underwater with the concrete which is improved segregation resistance of material, filling and self-leveling. It is generally to use this method with Europe and Japan as the central figure, and also the construction case is reported in korea. There's some advantages to add the fly ash in plain concrete. The objective of this study is to find the characteristics of fresh underwater antiwashout concrete which is followed by the blend rate of fly ash.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.480-485
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• 1996

A numerical method for perdicting the behavior of a reinforced concrete column under biaxial loading is proposed, using the layered finite element method. Concrete is assumed to exhibit strain softening and steel reinforcement is elastic-plastic. The bending theory assumptions are used and bond slip of reinforcement is meglected. To perdict the entire load-deformation characteristics, displacement control method is used. This method consider not only combined effect due to axial load and bending moment but also that due to bending moments. Predicted behaviors of reinforced concrete columns under biaxial loading through the numerical method proposed in this study show good agreements with test results.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.366-372
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• 1996

This paper persents the characteristics and properties of the five domestic and foreign-made anti-washout admixtures commercially available in Korea. These admixtures have been analysed by experiments to compare among others specifically on the following items : air content, slump-flow, hardening time, pH, filling condition, turbidity, content of chloride, compressive strength of underwater concrete and ratio of ambient / underwater concrete compressive strength. The mix design for comparison has been set according to the Japanese practicesince there is still no guideline concerning underwater concrete available domestically.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.905-908
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• 2006

In this study examines physical and mechanical properties the use of domestic low grade meta-kaolin in light weight porous concrete. For this purpose light weight porous concrete incorporating low grade meta-kaolin admixture, was tested for tensile strength and acoustic characteristics. Checking tensile strength of cement and low grade meta-kaolin mixture was used to determine the optimum mix proportion of the low grade meta-kaolin admixture. In this paper sound absorbing material has been investigated by using the light weight porous concrete.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.30-34
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• 2000

The concretes cast in the sea water would be likely to be rich mix and mass concrete. Therefore it is important to check out the hydration heat of concrete and to reduce it to prevent the concrete from processing the temperature crack. Recently the antiwashout agent is used on underwater concrete for preventing from the segregation of concrete in the water. The experimental studies were done for the combined cement replaced by fly ash 30%unit weight of binder to study on the characteristics of hydration heat of antiwashout underwater concrete, and its characteristic was discussed by comparing on cast in sea water with anther one in air. The present paper showed that the hydration heat concrete replaced by 30%of fly ash was more significantly reduced than the normal concrete. The hydration heat of antiwashout underwater concrete was highter than that of normal concrete, but it was reduced lower than the normal concrete by adding fly ash.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.715-718
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• 2004

The evaluation of durability of resin concrete was examined through various tests, i.e., compressive strength, absorption, abrasion, chemical attack resistance and bond between general and resin concrete. 2 types of concrete were used such as 40 MPa of general concrete and 90 MPa of resin concrete. The characteristics of resin concrete was more improved than that of general concrete, and especially, resin concrete was most effective on compressive strength, the resistance to $H_2SO_4$ solution attack and absorption. However, abrasion. is almost same between general concrete and resin concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1035-1040
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• 2001

Recently, Sea-sand containing high levels of chloride is being applied to on reinforced concrete structures due to the exhaustion of river-sand and environmental problems, which affects directly corrosion of rebar in the RC structures. In this paper, characteristics of corroded rebar before and after casting were studied. Test results showed that bond strength of rebar corroded after casting was decreased with increase of corrosion level more rapidly than that of rebar corroded before casting.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.151-156
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• 1994

This study is to investigate the quality of superplasticizers in domestic market. Therefore, the physico-chemical characteristics, the fluidity characteristics of fresh cement paste and mortar were tested. Also fresh and hardened properties of mortars and concretes using these superplasticizers were tested. From these results, differences of quality among superplasticizers are checked clearly in low water/cement ratio. And it is concluded that several superplasticizers have better dispersion ability than others in every tests. It has known that all samples are naphtalene sulfornate formaldehede types by the UV(ultra-violet) test.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.581-586
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• 2002

Addition of steel fiber to shotcrete is to improve the brittleness of concrete. Quality of steel fiber reinforced shotcrete can be evaluated by quantitive analysis of toughness characteristics after cracking. The toughness characteristics can be expressed by absolute value of energy absorption capacity, non-dimensional toughness index related to the energy absorption capacity, and equivalent flexural strength at arbitrary deflection. In this study, merits and demerits of flexural toughness by RTA round panel of Australia and other specifications have been analyzed.