Effect of polypropylene fiber on fracture properties of high-performance concrete composites

2012 ◽  
Vol 19 (4) ◽  
pp. 407-414 ◽  
Author(s):  
Peng Zhang ◽  
Qing-fu Li

AbstractA parametric experimental study has been conducted to investigate the effect of polypropylene fiber on the workability and fracture properties of high-performance concrete (HPC) composites containing fly ash and silica fume, with the five fiber volume fractions (0.04%, 0.06%, 0.08%, 0.1%, and 0.12%) used. The results indicate that the addition of polypropylene fiber decreases the workability of the HPC composites containing fly ash and silica fume. With the increase in the fiber volume fraction, both of the slump and the slump flow decrease gradually. Furthermore, the addition of polypropylene fiber has greatly improved the fracture parameters of concrete composite containing 15% fly ash and 6% silica fume, such as fracture toughness, fracture energy, effective crack length, maximum midspan deflection, the critical crack opening displacement, and the maximum crack opening displacement of the three-point bending beam specimens. When the fiber volume fraction increases from 0% to 0.12%, the fracture parameters increase gradually. The variation rules of the fracture parameters indicate that the capability of the polypropylene fiber to resist the crack propagation of the concrete composite containing 15% fly ash and 6% silica fume is becoming stronger and stronger with the increase in fiber volume fraction with the fiber volume fraction not above 0.12%.

2011 ◽  
Vol 346 ◽  
pp. 30-33
Author(s):  
Hong Wei Wang

A designed experimental study has been conducted to investigate the effect of polypropylene fiber on the compressive strength and flexural properties of concrete containing silica fume, a large number of experiments have been carried out in this study. The flexural properties include flexural strength and flexural modulus of elasticity. On the basis of the experimental results of the specimens of six sets of mix proportions, the mechanism of action of polypropylene fiber on compressive strength, flexural strength and flexural modulus of elasticity has been analyzed in details. The results indicate that there is a tendency of increase in the compressive strength and flexural strength, and the flexural modulus of elasticity of concrete containing silica fume decrease gradually with the increase of fiber volume fraction.


Author(s):  
P Zhang ◽  
Q Li ◽  
H Zhang

A parametric experimental study has been conducted to investigate the effect of fly ash on the fracture properties of high-performance concrete (HPC), with four fly ash contents used. By means of three-point bending method, the fracture toughness, fracture energy, effective crack length, critical crack opening displacement, and maximum crack opening displacement of the specimen were measured, respectively. The results indicate that fly ash has great improvement on the fracture parameters, and these fracture parameters gradually increase when the content of fly ash increases from 10 per cent to 20 per cent. However, these fracture parameters begin to decrease after the fly ash content exceeds 20 per cent. Besides, as the fly ash content increases from 10 per cent to 20 per cent, the relational curves between the vertical load and the mid-span deflection ( PV– δ), crack mouth opening displacement ( PV– CMOD), and crack tip opening displacement ( PV– CTOD) become plumper and plumper, which indicates that the capability of HPC containing fly ash to resist crack propagation is becoming stronger and stronger, while the curves become shriveled after the fly ash content exceeds 20 per cent. The contribution of fly ash on the fracture properties of HPC containing fly ash seems to be performed only when the fly ash content does not exceed 20 per cent.


2011 ◽  
Vol 346 ◽  
pp. 26-29 ◽  
Author(s):  
Hong Wei Wang

A designed experimental study has been conducted to investigate the effect of the fiber fraction of polypropylene fiber on the mechanical properties of concrete containing fly ash, a large number of experiments have been carried out in this study. The mechanical properties include compressive strength, splitting tensile strength and compressive modulus of elasticity. On the basis of the experimental results of the specimens of six sets of mix proportions, the mechanism of action of polypropylene fiber on these mechanical properties has been analyzed in details. The results indicate that there is a tendency of increase in the compressive strength and splitting tensile strength, and the modulus of elasticity of concrete containing fly ash decrease gradually with the increase of fiber volume fraction with appropriate content.


2021 ◽  
Vol 272 ◽  
pp. 02014
Author(s):  
Bo Chen ◽  
Liping Guo ◽  
Lihui Zhang ◽  
Wenxiao Zhang ◽  
Yin Bai ◽  
...  

The influence of polyvinyl alcohol (PVA) fiber volume fraction and fly ash content on the creep behavior of high ductility cementitious composites (HDCC) under compression was investigated. For this investigation, the creep behavior of four HDCC groups with cube compressive strength of 30–50 MPa, PVA fiber volume fraction of 1.5% and 2.0%, and fly ash content of 60% and 80% at 7 d and 28 d loading periods, respectively, were evaluated. A compressive creep model, which reflects the loading age and holding time, was established. The results revealed that when the load was applied at 7 d and 28 d, and then maintained for 245 d, the specific creep of HDCC ranged from 95×10-6/ MPa to 165×10-6/ MPa and from 59×10-6/ MPa to 135 × 10−6/ MPa, respectively. The corresponding creep coefficients ranged from 1.48 to 2.25 and from 1.10 to 1.94, respectively. The PVA fiber volume fraction and fly ash content were the main factors affecting the specific creep of HDCC, which increased with increasing fiber fraction and fly ash content. Under short-term loading, the fiber volume fraction played a leading role in the specific creep, and the fly ash content played the leading role during long-term loading. Furthermore, the specific creep and creep coefficient decreased significantly with increasing loading age. The classical creep model described by a power exponent function is suitable for HDCC.


Fibers ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 67 ◽  
Author(s):  
Manish Roy ◽  
Corey Hollmann ◽  
Kay Wille

This paper studied the influence of fiber volume fraction ( V f ), fiber orientation, and type of reinforcement bar (rebar) on the uniaxial tensile behavior of rebar-reinforced strain-hardening ultra-high performance concrete (UHPC). It was observed that the tensile strength increased with the increase in V f . When V f was kept constant at 1%, rebar-reinforced UHPC with fibers aligned with the load direction registered the highest strength and that with fibers oriented perpendicular to the load direction recorded the lowest strength. The strength of the composite with random fibers laid in between. Moreover, the strength, as well as the ductility, increased when the normal strength grade 60 rebars embedded in UHPC were replaced with high strength grade 100 rebars with all other conditions remaining unchanged. In addition, this paper discusses the potential of sudden failure of rebar-reinforced strain hardening UHPC and it is suggested that the composite attains a minimum strain of 1% at the peak stress to enable the members to have sufficient ductility.


2021 ◽  
Vol 5 (4) ◽  
pp. 142
Author(s):  
Li Li ◽  
Hai-Xin Sun ◽  
Yang Zhang ◽  
Bo Yu

Fiber is effective in restricting cracks and improving the toughness of geopolymer composites, but few studies have focused on the surface crack characteristics of fiber-reinforced geopolymer composites. In this paper, after flexural tests of polypropylene fiber-reinforced geopolymer mortar, the surface cracking image was collected by a digital camera and cracking information was extract by deep learning. Finally, the cracking and fractal characteristics were specifically discussed. The semantic segmentation network can accurately extract surface cracks for calculating various parameters. The results showed that the mean intersection over union (mIoU) and mean pixel accuracy (mPA) of the cracks are 0.8451 and 0.9213, respectively. Generally, the crack length, width, area, and fractal dimension of the specimen are all increased with the increase in the fiber volume fraction. These crack parameters grow rapidly when the fiber content is small, and the growth of the crack parameters gradually slows down as the fiber volume fraction increases to approximately 1.5%. The highest crack parameter values were found in the geopolymer mortar, with a 0.48 water–binder ratio and 12 mm fiber length. The variation of the bottom crack length and the side crack fractal dimension can be used to represent the overall crack variation patterns. Meanwhile, the crack parameters increase with the increased fiber factor in a quadratic function. Based on these crack parameters, the critical fiber factor and dense fiber factor of polypropylene fiber-reinforced geopolymer mortar were 200 and 550, respectively. They are greater than those of fiber-reinforced Portland cementitious composites. The influence of various crack parameters on the flexural strength is in the order of the crack area, width, length, and fractal dimension.


2013 ◽  
Vol 357-360 ◽  
pp. 1110-1114
Author(s):  
Dong Tao Xia ◽  
Xiang Kun Liu ◽  
Bo Ru Zhou

A set of new hybrid fiber reinforced high-performance concrete was developed and studied by experiment. The fibers incorporated the concrete are the collection of the steel fiber, modified polypropylene fiber and polypropylene with total fiber content not more than 1%. And the compressive test, splitting tensile test and the flexural toughness test were performed on eight groups of specimens. Based on the load-deflection and load-CMOD curves and the equivalent flexural tensile strength, the effect of fiber volume fraction and hybrid mode upon concrete's mechanical properties and post-peak behavior were investigated. The test results show that the mixing of the three different fibers can increase concrete's splitting tensile strength and flexural toughness more effectively with no significantly effect on compressive strength. The mixture of the three different fibers exist the optimization problem. Based on the results of the analysis, the compatible proportion of the three fibers is 0.7% steel fiber, 0.19% modified polypropylene fiber and 0.11% polypropylene fiber.


2012 ◽  
Vol 204-208 ◽  
pp. 3961-3964
Author(s):  
Yao Wang ◽  
Wei Hong Xuan ◽  
Yu Zhi Chen ◽  
Xiao Hong Chen ◽  
Gang Zheng

The compressive and flexural strength of ordinary mortar and fiber reinforced mortar with five different pp fiber content were tested in this paper. The results show that the compressive strength reduced gradually with PP fiber increasing, and the flexural strength increased when the fiber volume fraction is no more than 0.12%. The higher water ratio can weaken the cohesiveness of the fiber and cement material, and the influence of polypropylene fiber on the flexural strength of mortar decreased after soaking. The major strength damage in the process of curing is caused in the early age and appropriate amount of fiber is beneficial to reduce strength damage.


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