scholarly journals Effect of Super Plasticizers on Fresh and Hardened State Properties of Short Carbon Fiber Reinforced Electrically Conductive Concrete

2020 ◽  
Vol 8 (5) ◽  
pp. 2644-2650

This study enlightens the influence of superplasticizers (SP) on the dispersion and distribution of carbon fibers in the carbon fiber reinforced concrete (CFRC) cast with a low w/c ratio. The effectiveness of Polycarboxylate ether (PCE) based SP in the enhancement of workability of concrete and deagglomeration of carbon fibers in CFRC has been studied extensively in this study. The effect of PCE based SP on the compressive strength properties and electrical properties of the CFRC were also studied. The microstructure of the CFRC specimens was also analyzed to study the impact of SP on the deagglomeration of carbon fibers in CFRC. It was observed that the inclusion of carbon fibers in the dry concrete mixes without SP showed a negative effect on the functional properties of concrete whereas the inclusion of SP in the CFRC mixes improved the mobility and viscosity of the CFRC mixes. The fresh and hardened state properties were effectively enhanced with the use of SP in the CFRC mixes. The magnitude of decrease in electrical resistance was better in SP based CFRC resulting in more electrical conductivity. The microstructure of the CFRC indicated improvement in the distribution of carbon fibers in SP based CFRC.

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 972
Author(s):  
Yeou-Fong Li ◽  
Kun-Fang Lee ◽  
Gobinathan Kadagathur Ramanathan ◽  
Ta-Wui Cheng ◽  
Chih-Hong Huang ◽  
...  

The impact load, such as seismic and shock wave, sometimes causes severe damage to the reinforced concrete structures. This study utilized different lengths of chopped carbon fibers to develop a carbon-fiber-reinforced mortar (CFRM) and carbon-fiber-reinforced concrete (CFRC) with high impact and anti-shockwave resistance. The different lengths (6, 12, and 24 mm) of chopped carbon fibers were pneumatically dispersed and uniformly mixed into the cement with a 1% weight proportion. Then the CFRM and CFRC specimens were made for static and dynamic tests. The compressive and flexural strengths of the specimens were determined by using the standard ASTM C39/C 39M and ASTM C 293-02, respectively. Meanwhile, a free-fall impact test was done according to ACI 544.2R-89, which was used to test the impact resistances of the specimens under different impact energies. The CFRM and CFRC with a length of 6 mm exhibit maximum compressive strength. Both flexural and free-fall impact test results show that the 24 mm CFRM and CFRC enhances their maximum flexural strength and impact numbers more than the other lengths of CFRM, CFRC, and the benchmark specimens. After impact tests, the failure specimens were observed in a high-resolution optical microscope, to identify whether the failure mode is slippage or rupture of the carbon fiber. Finally, a blast wave explosion test was conducted to verify that the blast wave resistance of the 24 mm CFRC specimen was better than the 12 mm CFRC and benchmark specimens.


Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5881
Author(s):  
Yeou-Fong Li ◽  
Hsin-Fu Wang ◽  
Jin-Yuan Syu ◽  
Gobinathan Kadagathur Ramanathan ◽  
Ying-Kuan Tsai ◽  
...  

In this study, aramid fiber (Kevlar® 29 fiber) and carbon fiber were added into concrete in a hybrid manner to enhance the static and impact mechanical properties. The coupling agent presence on the surface of carbon fibers was spotted in Scanning Electron Microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) graphs. The carbon fiber with a coupling agent affected the mechanical strength of the reinforced concrete. At 1% fiber/cement weight percentage, the hybrid fiber-reinforced concrete (HFRC) prepared using Kevlar fiber and carbon fiber of 12 and 24 mm in length under different mix proportions was investigated to determine the maximum mechanical strengths. From the test results, the mechanical strength of the HFRC attained better performance than that of the concrete with only Kevlar or carbon fibers. Foremost, the mix proportion of Kevlar/carbon fiber (50–50%) significantly improved the compressive, flexural, and splitting tensile strengths. Under different impact energies, the impact resistance of the HFRC specimen was much higher than that of the benchmark specimen, and the damage of the HFRC specimens was examined with an optical microscope to identify slippage or rupture failure of the fiber in concrete.


2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Yanming Li ◽  
Xiaoyang Guo ◽  
Junlan Yang ◽  
Ming Li

In view of the oilfield well thin oil layer, small gap, and side drilling cementing after perforating and subsequent stimulation caused by the cement ring embrittlement (i.e., secondary channeling), the preparation of nano-SiO2/carbon fiber-reinforced body and its influence on the performance of oil well cement were studied to improve the cement stone and enhance its adaptability to oil well pressure in this study. Carbon fibers were treated by liquid phase oxidation and a coupling agent, and the “grafting to” was used to bond nano-SiO2 and carbon fibers. It was found that the mechanical properties of the enhanced cement stone are far better than those of the blank cement stone. The compressive strength and tensile strength of the enhanced oil well cement stone were increased by 25% and 26%, respectively, compared with those of the blank oil well cement sample; the modulus of elasticity was reduced by 29%. Finally, the enhancement mechanism of SiO2/carbon fiber reinforcement on cement stone was explored by infrared, scanning electron microscopy, and XRD patterns. The deflection effect, pull-out effect, and bridging effect of crack were obtained.


2020 ◽  
Vol 976 ◽  
pp. 180-185
Author(s):  
Gao Jie Liu ◽  
Er Lei Bai ◽  
Jin Yu Xu ◽  
Bo Xu Meng ◽  
Teng Jiao Wang ◽  
...  

The strength and deformation properties of carbon fiber reinforced concrete under different fiber volume loadings under impact loading were studied by using the ɸ100 mm split Hopkinson pressure bar (SHPB) test system. The results show that after the carbon fiber is added, the stress-strain curve of the specimen shows the platform section at the peak stress. The strength and peak strain of the concrete under the impact load increase first and then decrease with the increase of the carbon fiber volume. Trend, when the carbon fiber volume is 0.2%, the impact mechanical properties of concrete are significantly improved.


2020 ◽  
Vol 8 (6) ◽  
pp. 5171-5175

Fiber reinforced concrete is becoming increasingly more important in the construction field due to its numerous applications and advantages. Fibre reinforced concrete (FRC) is composed of fibres and matrix. Fibres constitute the reinforcements and the main source of strength while the matrix ‘glues’ all the fibres together in shape and transfers the stress between the reinforcing fibres. Different types of fibres in use are steel, glass, carbon, basalt and aramid. Fibre reinforced concrete has many advantages such as improvement in the mechanical properties like modulus of elasticity, deflection, energy absorption and crack resistance. This paper discusses the experimental investigations carried out on carbon fiber reinforced concrete under impact loading. Mix design is carried out for M25 grade of concrete reinforced with carbon fibers in proportions of 0%, 0.75%, 1.00% and 1.25% by volume fraction. The test results show that there is an increase in compressive, split tensile and flexural strengths of carbon fiber reinforced concrete (not discussed in this paper). The inclusion of 1% carbon fibers showed the maximum enhancement in strength and it can be considered as optimum dosage. When compared to conventional concrete, the crack width also reduced in carbon fiber reinforced concrete. Extensometer test was conducted to determine the modulus of elasticity of concrete. The main aim of this study is to understand the dynamic behavior of carbon fiber reinforced concrete under impact loading. For carrying out the drop-weight tests, eight slab specimens were casted. The edges of the slab were fixed on all four sides. FRC slab with 1% addition of carbon fibres gave the best results. There was a decrease in displacement and an increase in impact energy for an the aspect ratio of fiber is 45.


Author(s):  
Ryan Khawarizmi ◽  
Mohammad Sayem Bin Abdullah ◽  
Yinyin Han ◽  
Dave Kim ◽  
Patrick Kwon

Abstract Carbon fiber reinforced plastics (CFRP) composites are difficult-to-machine materials due to extensive tool wear. This paper investigates the impact of carbon fiber types on tool wear in edge-trimming CFRPs, each with particular ply angle of 0°, 45°, 90°, or 135°, using uncoated tungsten carbide endmills at the high spindle speed of 6000 rpm and the constant feed of 0.0508 mm/rev. Three distinct types of carbon fiber tows, including T300 as standard modulus (SM), IM-7 as intermediate modulus (IM), and K13312 as high modulus (HM), have been vacuum infused into CFRP laminates and edge-trimmed to investigate wear characteristics. Three wear criteria measured are flank wear, edge rounding radii, and worn area. The results show that tool wear is influenced by carbon fiber properties, such as fiber tensile strength, tensile modulus, and fiber microstructure. Overall, intermediate modulus carbon fibers with the highest tensile strength produced the most extensive tool wear due to brushing effects by abrasive carbon fibers. Out of four fiber directions, the largest tool wear was obtained from the 45° angle, while the lowest tool wear occurred in the 0° angle.


Author(s):  
Ryan Khawarizmi ◽  
Patrick Kwon ◽  
Mohammad Sayem Bin Abdullah ◽  
Yinyin Han ◽  
Dave Kim

Abstract Although carbon fiber reinforced plastics (CFRP) materials are widely used in high-strength and low-weight applications such as aerospace, defense, and automotive industries, they are one of the difficult-to-machine materials due to extensive tool wear. This paper investigates the impact of carbon fiber types on tool wear in edge-trimming CFRPs, each with particular ply angle of 0°, 45°, 90°, or 135°, using uncoated tungsten carbide endmills at a high spindle speed of 6000 rpm and a constant feed of 0.0508 mm/rev. Three distinct types of carbon fiber tows, including T300 as standard modulus (SM), IM-7 as intermediate modulus (IM), and K13312 as high modulus (HM), have been vacuum infused into CFRP laminates and edge-trimmed to investigate wear characteristics. Three wear criteria measured are flank wear, edge rounding radii, and worn area. The results show that tool wear is influenced by carbon fiber properties, such as fiber tensile strength, tensile modulus, and fiber microstructure. Overall, Intermediate modulus carbon fibers with the highest tensile strength produced the largest tool wear due to brushing effects by abrasive carbon fibers. Out of four fiber directions, the largest tool wear was obtained from the 45° angle while the lowest tool wear occurred in the 0° angle.


2021 ◽  
Vol 13 (12) ◽  
pp. 6829
Author(s):  
Yeou-Fong Li ◽  
Jie-You Li ◽  
Gobinathan Kadagathur Ramanathan ◽  
Shu-Mei Chang ◽  
Ming-Yuan Shen ◽  
...  

In the last decade, waste carbon fiber-reinforced plastic (CFRP) products have not been properly recycled and reused, and they sometimes cause environmental problems. In this paper, the microwave-assisted pyrolysis (MAP) technology was utilized to remove the resin from the CFRP bicycle frame, which was recycled into carbon fiber. A scanning electron microscope (SEM) and single filament tensile test were used to observe and compare the difference between recycled carbon fiber and normal carbon fiber. The mechanical performances of carbon fiber-reinforced concrete (CFRC) were investigated with static and dynamic tests under three different fiber/cement weight proportions (5‰, 10‰, and 15‰). Three different kinds of carbon fiber were used in this study, normal carbon fiber, carbon fiber without coupling agent, and recycled carbon fiber. The experimental program was tested according to ASTM C39-01, ASTM C293, and ACI 544.2R standards for compression, flexural, and impact test, respectively. From the experimental results, addition of 10‰ of carbon fiber into the concrete exhibited maximum compressive and flexural strength. The impact performance of recycled carbon fiber improved the highest impact number compared with normal carbon fiber under different impact energy.


2020 ◽  
Vol 40 (5) ◽  
pp. 415-420 ◽  
Author(s):  
Yasin Altin ◽  
Hazal Yilmaz ◽  
Omer Faruk Unsal ◽  
Ayse Celik Bedeloglu

AbstractThe interfacial interaction between the fiber and matrix is the most important factor which influences the performance of the carbon fiber-epoxy composites. In this study, the graphitic surface of the carbon fibers was modified with graphene oxide nanomaterials by using a spray coating technique which is an easy, cheap, and quick method. The carbon fiber-reinforced epoxy matrix composites were prepared by hand layup technique using neat carbon fibers and 0.5, 1 and 2% by weight graphene oxide (GO) modified carbon fibers. As a result of SEM analysis, it was observed that GO particles were homogeneously coated on the surface of the carbon fibers. Furthermore, Young's modulus increased from 35.14 to 43.40 GPa, tensile strength increased from 436 to 672 MPa, and the elongation at break was maintained around 2% even in only 2% GO addition.


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