Mechanical Behavior of UHPC(Ultra High Performance Concrete) According to Hybrid Use of Steel Fibers

2011 ◽  
Vol 287-290 ◽  
pp. 453-457 ◽  
Author(s):  
Gum Sung Ryu ◽  
Su Tae Kang ◽  
Jung Jun Park ◽  
Kyung Taek Koh ◽  
Sung Wook Kim
Keyword(s):  
Flexural Strength ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Single Type ◽  
Behavioral Characteristics ◽  
Total Rate ◽  
Ultra High Performance Concrete ◽  
Load Bearing Capacity

This intends to examine the flexural behavioral characteristics of hybrid UHPC using a mix of steel fibers with different lengths. Three types of fibers are adopted with fixed diameter of 0.2 mm and lengths of 13, 16.3 and 19.5 mm (aspect ratio of 65, 82 and 98, respectively). Comparative analysis of the flexural strength, load bearing capacity, deflection and toughness is performed adopting a mix use of these 3 types of steel fibers with ratio of 2% and 1.5%. The results show that the hybrid use of steel fibers improves significantly the flexural strength and flexural toughness compared to the use of a single type of fiber. When steel fibers with lengths of 16.3 mm and 19.5mm are admixed at a rate of 1% each, UHPC develops a flexural strength larger by 27% (maximum 50%) than conventional UHPC admixed with 2% of steel fiber with length of 13 mm. Moreover, flexural strength similar to that of conventional UHPC is secured when steel fibers with lengths of 16.3 mm and 19.5mm are admixed at respective rates of 0.5% and 1% (total rate of 1.5%).

scholarly journals Flexural Strength Evaluation of Reinforced Concrete Members with Ultra High Performance Concrete

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Baek-Il Bae ◽  
Hyun-Ki Choi ◽  
Chang-Sik Choi
Keyword(s):  
Flexural Strength ◽  
High Performance ◽  
Strain Softening ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
High Strength ◽  
Tension Stress ◽  
Compression Stress ◽  
Ultra High Performance Concrete ◽  
Stress Block

Flexural strength evaluation models for steel fiber reinforced ultra high strength concrete were suggested and evaluated with test results. Suggested flexural strength models were composed of compression stress blocks and tension stress blocks. Rectangular stress block, triangular stress block, and real distribution shape of stress were used on compression side. Under tension, rectangular stress block distributed to whole area of tension side and partial area of tension side was used. The last model for tension side is realistic stress distribution. All these models were verified with test result which was carried out in this study. Test was conducted by four-point loading with 2,000 kN actuator for slender beam specimen. Additional verifications were carried out with previous researches on flexural strength of steel fiber reinforced concrete or ultra high strength concrete. Total of 21 test specimens were evaluated. As a result of comparison for flexural strength of section, neutral axis depth at ultimate state, models with triangular compression stress block, and strain-softening type tension stress block can be used as exact solution for ultra high performance concrete. For the conservative and convenient design of section, modified rectangular stress block model can be used with strain softening type tension stress block.

Evaluation of Fundamental UHPC Properties According to the Shape of Steel Fiber

2010 ◽  
Vol 452-453 ◽  
pp. 717-720 ◽  
Author(s):  
Gum Sung Ryu ◽  
Su Tae Kang ◽  
Jung Jun Park ◽  
Kyung Taek Koh ◽  
Sung Wook Kim
Keyword(s):  
Aspect Ratio ◽  
Flexural Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Flexural Behavior ◽  
Ultra High Performance Concrete ◽  
Aspect Ratios ◽  
Strength Tests ◽  
Shaped Fibers

This paper intends to examine the effects if the length and shape of steel fibers on the mechanical characteristics of ultra-high performance concrete (UHPC). Accordingly, the length (l) of the steel fibers with diameter (d) of 0.2 mm is varied as 13 mm, 16.3 mm and 19.5 mm and their corresponding aspect ratios (l/d) are 65, 82 and 98. Straight and wave-shaped fibers are adopted to manufacture UHPC. Thereafter, the effects of the aspect ratio and characteristics of the wave-shape of the steel fibers on the strength characteristics of UHPC are examined through compressive and flexural strength tests. The results showed small differences in the workability and compressive behavior but revealed that changing the length of the fibers and increasing the aspect ratio are improving the flexural behavior of UHPC. Specifically, the flexural strength was enhanced by 25% and the flexural toughness by 30%. Compared to rectilinear fibers, the adoption of wave-shaped fibers is seen to degrade the flexural behavior regardless of the aspect ratio. Consequently, using straight steel fibers and adopting larger aspect ratio seems advisable to improve the toughness of UHPC.

Experimental Study of Strengthening and Toughening for Recycled Steel Fiber Reinforced Ultra-High Performance Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 104-111 ◽  
Author(s):  
Gai Fei Peng ◽  
Xu Jing Niu ◽  
Qian Qian Long
Keyword(s):  
Mechanical Properties ◽  
Fracture Energy ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Ultra High Performance Concrete ◽  
Tensile Splitting Strength ◽  
Recycled Steel

This paper presents an experimental investigation on mechanical properties (including compressive strength, tensile splitting strength and fracture energy) of ultra-high performance concrete (UHPC) with recycled steel fiber, compared with none fiber and industrial steel fiber reinforced UHPC. Moreover, the microscopic observation of fracture energy was carried out. All specimens were prepared at 0.18 water /binder (W/B) ratio and the dosage of steel fiber was controlled at 60 kg/m3. The results indicate that recycled steel fiber has a significant effect on enhancing strength and toughness of UHPC. And owing to the crimped shape, higher tensile strength (1800-2000 MPa) and appropriate diameter (1 mm) of recycled steel fiber, the steel fibers of UHPRSFRC will not immediately be pulled off and necking phenomenon is distinct.

scholarly journals Mechanical Properties and Anti-Spalling Behavior of Ultra-High Performance Concrete with Recycled and Industrial Steel Fibers

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 783 ◽  
Author(s):  
Juan Yang ◽  
Gai-Fei Peng ◽  
Guo-Shuang Shui ◽  
Gui Zhang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fracture Energy ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Ultra High Performance Concrete ◽  
Explosive Spalling ◽  
Recycled Steel

Experimental investigations on the mechanical properties of ultra-high performance concrete (UHPC) incorporating two types of recycled steel fiber processed from waste tires and three types of industrial steel fiber were carried out for comparison. Mechanical properties of UHPC include compressive strength, splitting tensile strength, fracture energy, and elastic modulus. Their explosive spalling behaviors under high temperatures were also investigated. The results show that all types of steel fiber exhibit a beneficial effect on the mechanical properties and the anti-spalling behavior of UHPC, except that recycled steel fiber with rubber attached (RSFR) has a slightly negative effect on the compressive strength of UHPC. Compared to industrial steel fibers, recycled steel fibers have a more significant influence on improving the splitting tensile strength and fracture energy of UHPC, and the improvement of RSFR was much higher than that of recycled steel fiber without rubber (RSF). UHPC that incorporates industrial hooked-end steel fiber (35 mm in length and 0.55 mm in diameter) exhibits the best resistance to explosive spalling, and the second is the RSF reinforced UHPC. The positive relationship between the fracture energy and the anti-spalling behavior of steel fiber reinforced UHPC can be presented. These results suggest that recycled steel fiber can be a toughening material and substitute for industrial steel fibers to be used in ultra-high performance concrete, especially RSFR.

scholarly journals Experimental Study on Shear Performance of Cast-In-Place Ultra-High Performance Concrete Structures

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3254 ◽  
Author(s):  
Li ◽  
Feng ◽  
Ke ◽  
Pan ◽  
Nie
Keyword(s):  
Shear Strength ◽  
High Performance ◽  
Fiber Volume Fraction ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Steel Fibers ◽  
Direct Shear ◽  
Ultra High Performance Concrete ◽  
Fiber Volume

In order to study the direct shear properties of ultra-high performance concrete (UHPC) structures, 15 Z-shaped monolithic placement specimens (MPSs) and 12 Z-shaped waterjet treated specimens (WJTSs) were tested to study the shear behavior and failure modes. The effects of steel fiber shape, steel fiber volume fraction and interface treatment on the direct shear properties of UHPC were investigated. The test results demonstrate that the MPSs were reinforced with steel fibers and underwent ductile failure. The ultimate load of the MPS is about 166.9% of the initial cracking load. However, the WJTSs failed in a typical brittle mode. Increasing the fiber volume fraction significantly improves the shear strength, which can reach 24.72 MPa. The steel fiber type has little effect on the shear strength and ductility, while increasing the length of steel fibers improves its ductility and slightly reduces the shear strength. The direct shear strength of the WJTSs made from 16 mm hooked-type steel fibers can reach 9.15 MPa, which is 2.47 times the direct shear strength of the specimens without fibers. Finally, an interaction formula for the shear and compressive strength was proposed on the basis of the experimental results, to predict the shear load-carrying capacity of the cast-in-place UHPC structures.

Experimental Study on Mechanical Properties of Steel Fiber Reinforced High Performance Concrete

2013 ◽  
Vol 859 ◽  
pp. 56-59 ◽  
Author(s):  
Yong Qiang Ma
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Flexural Strength ◽  
High Performance ◽  
Steel Fiber ◽  
High Performance Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced

A large number of experiments have been carried out in this study to reveal the effect of the steel fiber dosage on the mechanical properties of HPC (high performance concrete). The mechanical property includes compressive strength, elastic modulus and flexural strength. The results indicate that the addition of steel fiber increase the compressive strength, elastic modulus and flexural strength of HPC. When the steel fiber dosage is less than 2%, these mechanical property parameters are increasing gradually with the increase of steel fiber dosage, while these parameters begin to decrease when the steel fiber dosage is more than 2%. With the development of HPC, the application of steel fibers in HPC becomes more and more popular. In the actual construction of steel fiber reinforced HPC, the dosage of steel fiber should be controlled strictly in order to ensure that the steel fibers can perform their best improvement on high performance concrete.

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