• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.11a
• /
• pp.55-56
• /
• 2014

In this research, the effect of types of aggregate and SP on fundamental properties of ultra-high performance concrete of 80 MPa of compressive strength was evaluated to provide solution for high cost of ultra-high performance concrete. As the results of a series of tests, the mixture using limestone and silica aggregates showed improved workability rather than the mixture using granite aggregate. For compressive strength of UHPC, the UHPC mixtures using limestone and silica aggregates showed higher compressive strength than the UHPC mixture using granite aggregate while all mixtures satisfied target compressive range.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2013.11a
• /
• pp.34-35
• /
• 2013

In this study, the ultra high strength concrete which have 80, 130, 180MPa took the heat from 20℃ to 700℃ and the 0, 20% stress in normal condition's to evaluate stress-strain, residual compressive strength and thermal expansion deformation were evaluated. The heating speed of specimen was 0.77℃/min 20~50℃, 50℃ before the target temperature, and the other interval's heating speed was 1℃/min. As a result, the stress-strain curve of non-load specimen showed the liner behavior at high temperature when the specimen's strength increased more. If ultra high strength concrete got loads, its compressive strength tended to decrease different from the normal strength concrete. The thermal expansion deformation was expanded from a vitrification of quartz over 500℃. however, over the 600℃, it was shrinked because of the dehydration of the combined water.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.5
• /
• pp.171-178
• /
• 2006

It was presented that the spalling of high strength concrete exposed to high temperature could be reduced by using polypropylene fiber. However, as the concrete strength increase, the demanded quantity of PP fiber increase and this results in the loss of workability of ultra high strength concrete. The silica fume which is essentially mixed in ultra high strength concrete decrease the permeability of concrete, and this will increase the degree of spalling. In this study the effect of silica fume on the spalling of ultra high strength concrete and the fire resisting efficiency of PP fiber and poly vinyl alchol, instead of PP fiber, for the security of workability were experimentally examined.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.86-87
• /
• 2017

The high-temperature creep of Ultra-High-Strength Concrete (UHSC) has been investigated in this study. The purpose of this study is to evaluated total strain and high-temperature creep at elevated temperatures under loading condition of UHSC. As results, Total strain of UHSC increased showing shrinkage with increasing compressive strength. The high-temperature creep of UHSC increased with the temperature and higher level of compressive strength showed bigger high-temperature creep.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2013.05a
• /
• pp.91-92
• /
• 2013

The strength of ultra-high-strength concrete can be reduced even if the spalling is prevented at a high temperature. Therefore, in this study, we measured internal temperature history and residual compressive strength using a 300×300×450mm short column specimens which use the fiber(NY 0.15+PP 0.10+SF 0.30vol·%) and respectively silica sand, washed sand, the slag sand. As a result, the temperature history and residual compressive strength are almost similar regardless of the fine aggregate types.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.3
• /
• pp.69-75
• /
• 2017

Ultra-high performance concrete and high ductile cementless composite are considered as promising construction materials because those exhibits higher performance in terms of high strength and high ductility. The purpose of this study is to investigate experimentally the compressive strength and tensile behavior of ultra-high performance concrete and high ductile cementless composite. A series of experiments including density, compressive strength, and uniaxial tension tests were performed. Test results showed that the compressive strength and tensile strength of alkali-activated slag based high ductile cementless composite were lower than those of ultra-high performance concrete. However, the tensile strain capacity and toughness of alkali-activated slag based high ductile cementless composite were higher than those of ultra-high performance concrete. And it was exhibited that a high ductility up to 7.89% can be attainable by incorporating polyethylene fiber into the alkali-activated slag based cementless paste.

• Journal of the Korea Convergence Society
• /
• v.11 no.11
• /
• pp.211-217
• /
• 2020

There is an increasing demands of more efficient and economical ways of mold making according to the spreading trend of small quantity batch production system. Therefore, this study aims to examine the applicability of ultra high strength concrete, which has a compressive strength over 80MPa, as a mold material. The ultra high strength concrete has several advantages such as lower cost, lighter weight and convenience of shape making compared to the traditional mold materials. Although the strength of the ultra high strength concrete is lower than that of the tool steel, it was considered to be useful for small batch processes with relatively low pressure. Therefore, in this study, a prototype mold for reaction injection molding of polyurethane was developed using ultra high strength concrete and it was examined that the possibility and characteristics of concrete as a mold material.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.11a
• /
• pp.41-42
• /
• 2023

The physical performance of high-strength concrete deteriorates when exposed to high temperatures such as fire. In particular, in the case of ultra-high-strength concrete, there is a high possibility of explosion due to internal water pressure and thermal expansion due to the tight internal structure. In this paper, a fire resistance certification test was conducted for field application of ultra-high-strength fire-resistant concrete, and the fire resistance performance (temperature rise of main rebar) was compared according to the structural concrete cover thickness. As a result, when the covering thickness was 40 mm, three structures did not meet the certification standards, and when the covering thickness was 50 mm, all structures met the fire resistance certification standards.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05a
• /
• pp.79-82
• /
• 2005

This study reports on the structural characteristics of slab-column connections using an ultra-high-strength-fiber-reinforced concrete from new and retrospective data. The parameters investigated were the ' puddling ' of ultra-high-strength-fiber-reinforced concrete and the use of high-strength concrete in the slab. The effects of these parameters on the punching shear capacity, negative moment cracking, and stiffness of the two-way slab specimens are investigated. Furthermore, the ACI Code (2002), the CSA Standard (1994), the BS Standard (1985) and the CEB-FIP Code (1990) predictions are compared to the experimental results obtained from some slab-column connections tested in this experiment and those tested by other investigators. The beneficial effects of the ultra-high-strength-fiber-reinforced concrete puddling and of the use of high-strength concrete are demonstrated. It is also concluded that the punching shear strength of slab-column connections is a function of the flexural reinforcement ratio.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.313-316
• /
• 2004

In this paper, it was assessed durability of ultra-high strength cementitious composites(UHSCC) with the range of 180MPa of compressive strength through the test method of chloride ion resistance, carbonation, freezing-thawing resistance, permeability. In order to compare with ultra-high strength cementitious composites, normal concrete and high-strength concrete were also tested. As the experimental result, it showed that UHSCC was cleary superior to the durability performance of normal concrete and high-strength concrete.