• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.31-37
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• 2018

This study evaluates the dynamic tensile behavior of HPFRCC according to compressive strength levels of 100, 140 and 180 MPa. Firstly, the compressive stress-strain relationship of 100, 140 and 180 MPa class HPFRCC was analyzed. As a result, the compressive strengths were 112, 150 and 202 MPa, respectively, and the elastic modulus increased with increasing compressive strength. The static tensile strengths of HPFRCC of 100, 140 and 180 MPa were 10.7, 11.5 and 16.5 MPa, and tensile strength also increased with increasing compressive strength. On the other hand, static tensile strength and energy absorption capacity at 100 and 140 MPa class HPFRCC showed no significant difference according to the compressive strength level. It was influenced by the specification of specimen and the arrangement of steel fiber. As a result of evaluating the dynamic impact tensile strength of HPFRCC, tensile strength and dynamic impact factor of all HPFRCCs tended to increase with increasing strain rate from 10-1/s to 150/s. In the same strain rate range, the DIF of the tensile strength was measured higher as the compressive strength of HPFRCC was lower. It is considered that HPFRCC of 100 MPa is the best in terms of efficiency. Therefore, it is advantageous to use HPFRCC with high compressive strength when a high level of tensile performance is required, and it is preferable to use HPFRCC close to the target compressive strength for more efficient approach at a high strain rate such as explosion.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.35-41
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• 2005

Recently, various fiber reinforced cementitious composites are used in order to solve problems of concrete as the brittleness breaking. Especially, in U.S.A., Europe, and Japan, ultra-high strength steel fiber reinforced cementitious composites(ultra-high strength SFRCC) with compressive strength in excess of 100 MPa were developed. However few studies have been investigated on the high-strength SFRCC in Korea. Therefore, in this paper, to make ultra-high strength SFRCC with the range of compressive strength 180MPa, it was investigated the constitute factors of ultra-high strength SFRCC influenced on the compressive strength. The experimental variables were water-binder ratio, replacement of silica fume, size and proportion of sand, type and replacement of filling powder, and using of steel fiber in ultra-high strength SFRCC. As a result, in water-binder ratio 0.20, we could make ultra-high strength SFRCC with compressive strength of 180MPa through using of silica fume, quartz sand with below 0.5mm filling powder and steel fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.288-291
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• 2004

In this paper, to make ultra-high strength SFRCC with the range of compressive strength 180MPa, it was investigated the constitute factors of ultra-high strength SFRCC influenced on the compressive strength. The experimental variables were water-cementitious ratio, replacement of silica fume, size and proportion of sand, type and replacement of filling powder, and using of steel fiber in ultra-high strength SFRCC. As a result, in water-binder ratio 0.18, we could make ultra-high strength SFRCC with compressive strength 180MPa through using of silica fume, quartz sand with below 0.5mm, filling powder and steel fiber.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4930-4935
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• 2015

In the actual research fields, the studies for applications of 180 MPa ultra high performance concrete (UHFRCC) to compressive members are limited due to its very high compressive strength. In this study, in order to find its practical use, UHPC was producted by using twin-shaft mixer batch plant. Also, to get basic research data for the design specification of UHPC compressive members, a series of draft experiments, including short columns with square and circular sections, were performed and its failure modes and behaviors were assessed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.5015-5020
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• 2015

Push-out test is performed on perfobond shear connectors applying ultra high performance concretes with compressive strength higher than 80 MPa to evaluate their shear resistance. The test variables are chosen to be the diameter and number of dowel holes and, the change in the shear strength of the perfobond rib connector is examined with respect to the strength of two types of UHPC: steel fiber-reinforced concrete with compressive strength of 180 MPa and concrete without steel fiber with compressive strength of 80 MPa. The test results reveal that higher concrete strength and larger number of holes increased the shear strength, and that higher increase rate in the shear strength was achieved by the dowel action.

• Structural Engineering and Mechanics
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• v.31 no.6
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• pp.697-716
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• 2009

This paper summarizes an experimental and analytical study on the seismic behavior of high strength reinforced concrete columns under cyclic loading. In total six cantilever columns with different sizes and concrete compressive strengths were tested. Three columns, small size, had a $325{\times}325$ mm cross section and the three other columns, medium size, were $520{\times}520$ mm. Concrete compressive strength was 80, 130 and 180 MPa. All specimens were designed in accordance with the Japanese design guidelines. The tests demonstrated that, for specimens made of 180 MPa concrete compressive strength, spalling of cover concrete was very brittle followed by a significant decrease in strength. Curvature was much important for the small size than for the medium size columns. Concrete compressive strength had no effect on the curvature distribution for a drift varying between -2% and +2%. However, it had an effect on the drift corresponding to the peak moment and on the equivalent viscous damping variation. Simple equations are proposed for 1) evaluating the concrete Young's modulus for high strength concrete and for 2) evaluating the moment-drift envelope curves for the medium size columns knowing that of the small size columns. Experimental moment-drift and axial strain-drift histories were well predicted using a fiber model developed by the authors.

• Fire Science and Engineering
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• v.24 no.2
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• pp.44-51
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• 2010

This study, to develop the technology of the fire resistance design of CFT structure based on fire resistance performance design, was suppose to use as basic data for performance design through a measure of temperature and deformation of the CFT specimen as parameter is the concrete compressive strength and load ratio. In accordance with KS F 2257-1 and 7, 24 MPa and 40 MPa and the load ratio of 0.9, 0.6 and 0.2 were imposed on a square column and as a result of evaluating in accordance with the fire resistance criteria, in case of 24 MPa, the fire resistance performance was improved by 73 minutes when the load ratio was reduced by 0.3. And when it comes to 40 MPa, the fire resistance was 31 minutes and 180 minutes when a load ratio was 0.6 and 0.2, respectively. As a result of evaluating fire resistant performance depending on variation of internal concrete strength, it proved that the higher the strength the lower the fire resistance.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.117-124
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• 2010

The aggregate, which does not satisfy the standard of KS F 2573, was selected for this investigation. The 28day compressive strength of recycled aggregate concrete without pozzolan material was 21.7MPa, which was less than the strength of concrete made with crushed stone. However, the compressive strength at 28 days was improved by mixing early rapid hardening cement to the cement at the weight ratio of 2.5%. Furthermore, the compressive strength at 91 days and 180 days increased significantly by adding fly ash, slag powder, and diatom powder. The tensile strength of recycled aggregate concrete with pozzolan material also increased about 40% compared to the general concrete. Futhermore, the shrinkage and creep of recycled aggregate concrete with fly ash and slag powder was a little decreased that of recycled aggregate concrete with fly ash and diatom powder. Relationship between compressive strength and creep coefficient was shown to the linear relation like as ${\sigma}_c=-30CF+404$.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.607-614
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• 2001

This paper describes the design and construction of main Arch bridge using Ultra-high performance concrete, Ductal in the Sunyudo pedestrian bridge project. Ductal is a new family of cementing materials with remarkable properties. Its mechanical characteristics reach unique values, with compressive strength in industrial use of 180 to 230 MPa and bending tensile strength of 50 to 80 MPa. By the use of Ductal, main Arch bridge crossing the Han-river is designed to the span 120m-long with optimized $\pi$ shape section.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.5-6
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• 2017

This study is to analyze the properties of concrete according to the types of binders and cement powder and to utilize them as fundamental data for the development of early strength concrete. In the case of fluidity, all of the formulations satisfied the 180±25mm, and the flowability of HSF was decreased by high fineness cement. For the air content, 4.5±1.5% of the total content was satisfied. Compressive strength of HSF was found to satisfy the 5MPa in 2days of aging. In case of 28 days of aging, the strength of HSF was more than 24MPa.