scholarly journals An Anchoring Groove Technique to Enhance the Bond Behavior between Heat-Damaged Concrete and CFRP Composites

Buildings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 232
Author(s):  
Rajai Al-Rousan ◽  
Mohammad AL-Tahat
Keyword(s):  
Elevated Temperatures ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Bond Behavior ◽  
Reinforced Polymer ◽  
Cfrp Composites ◽  
Bonding Area ◽  
Cfrp Sheet ◽  
Cfrp Composite ◽  
Type Of Failure

This experimental study was conducted to evaluate the effectiveness of using carbon fiber-reinforced polymer (CFRP) composites with special anchoring grooves, specifically in terms of the ability of the concrete–CFRP bond to withstand elevated temperatures. The obtained findings of this experiment clearly highlighted the effectiveness of the direction of the anchoring grooves on the behavior of the concrete–CFRP bonding area. The results also showed that high temperatures lessen the bond’s strength and the ultimate slippage. On the other hand, this study showed that increasing the length of the CFRP sheet resulted in enhancement of the bond’s strength and slippage. When exposed to temperatures above 500 °C, the structures’ residual splitting and compression strength decreased significantly, resulting in the bond’s strength reducing to 67% and the slippage to 19%, with respect to the control samples. In the non-grooved and vertically grooved beams, the CFRP–concrete bond showed a skin-peeling type of failure. It appeared, also, that the temperature and the number of anchored grooves significantly affected the bonding area of the surface; as the surface was exposed to failure in adhesion, more concrete remained attached to the CFRP composite, signifying a stronger attachment.

scholarly journals Tensile Behavior of Carbon Fiber-Reinforced Polymer Composites Incorporating Nanomaterials after Exposure to Elevated Temperature

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Gia Toai Truong ◽  
Hai Van Tran ◽  
Kyoung-Kyu Choi
Keyword(s):  
Tensile Strength ◽  
Elevated Temperatures ◽  
Tensile Behavior ◽  
Ultimate Strain ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Multiwalled Carbon ◽  
Maximum Tensile Strength ◽  
Reinforced Polymer ◽  
Cfrp Composites

This study experimentally examined the effect of nanomaterial on the tensile behavior of carbon fiber-reinforced polymer (CFRP) composites. Multiwalled carbon nanotubes (MWCNT), graphene nanoplatelets (GnPs), and short multiwalled carbon nanotubes functionalized COOH (S-MWCNT-COOH) with 1% by weight were used as the primary test parameters. In the present test, S-MWCNT-COOH was more effective than the others in improving the maximum tensile strength, ultimate strain, and toughness of the CFRP composites. The use of S-MWCNT-COOH increased the maximum tensile strength, ultimate strain, and toughness of the CFRP composites by 20.7, 45.7, and 73.8%, respectively. In addition, tensile tests were carried out for CFRP composites with S-MWCNT-COOH after subjection to elevated temperatures ranging from 50 to 200°C. The test results showed that the tensile strength, ultimate strain, and toughness were significantly reduced with increasing temperature. At a temperature level of 100°C, the reduction of the maximum tensile strength, ultimate strain, and toughness was 36.5, 37.1, and 60.0%, respectively. However, for the specimens subjected to the elevated temperatures ranging from 100 to 200°C, the tensile behavioral properties were constantly maintained. Finally, various analytical models were applied to predict the tensile strength of the CFRP composites with S-MWCNT-COOH. By using the calibrated parameters, the tensile strengths predicted by the models showed good agreement with the experimental results.

Restoring Initially Cracked Reinforced Concrete Beams utilizing Carbon Fiber Reinforced Polymer Strips

2019 ◽  
Vol 7 (1) ◽  
pp. 30-34
Author(s):  
A. Ajwad ◽  
U. Ilyas ◽  
N. Khadim ◽  
Abdullah ◽  
M.U. Rashid ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Loading Test ◽  
Control Beam ◽  
Reinforced Polymer ◽  
Cfrp Sheet ◽  
Carbon Fiber Reinforced

Carbon fiber reinforced polymer (CFRP) strips are widely used all over the globe as a repair and strengthening material for concrete elements. This paper looks at comparison of numerous methods to rehabilitate concrete beams with the use of CFRP sheet strips. This research work consists of 4 under-reinforced, properly cured RCC beams under two point loading test. One beam was loaded till failure, which was considered the control beam for comparison. Other 3 beams were load till the appearance of initial crack, which normally occurred at third-quarters of failure load and then repaired with different ratios and design of CFRP sheet strips. Afterwards, the repaired beams were loaded again till failure and the results were compared with control beam. Deflections and ultimate load were noted for all concrete beams. It was found out the use of CFRP sheet strips did increase the maximum load bearing capacity of cracked beams, although their behavior was more brittle as compared with control beam.

scholarly journals Femtosecond Laser Drilling of Cylindrical Holes for Carbon Fiber-Reinforced Polymer (CFRP) Composites

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2953
Author(s):  
Hao Jiang ◽  
Caiwen Ma ◽  
Ming Li ◽  
Zhiliang Cao
Keyword(s):  
Carbon Fiber ◽  
Femtosecond Laser ◽  
Picosecond Laser ◽  
Laser Drilling ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Laser Parameters ◽  
Reinforced Polymer ◽  
Cfrp Composites ◽  
Cylindrical Holes

Ultrafast laser drilling has been proven to effectively reduce the heat-affected zone (HAZ) of carbon fiber-reinforced polymer (CFRP) composites. However, previous research mainly focused on the effects of picosecond laser parameters on CFRP drilling. Compared with a picosecond laser, a femtosecond laser can achieve higher quality CFRP drilling due to its smaller pulse width, but there are few studies on the effects of femtosecond laser parameters on CFRP drilling. Moreover, the cross-sectional taper of CFRP produced by laser drilling is very large. This paper introduces the use of the femtosecond laser to drill cylindrical holes in CFRP. The effect of laser power, rotational speed of the laser, and number of spiral passes on HAZ and ablation depth in circular laser drilling and spiral laser drilling mode was studied, respectively. It also analyzed the forming process of the drilling depth in the spiral drilling mode and studied the influence of laser energy and drilling feed depth on the holes’ diameters and the taper. The experimental results show that the cylindrical hole of CFRP with a depth-to-diameter ratio of about 3:1 (taper < 0.32∘, HAZ < 10 m) was obtained by using femtosecond laser and a spiral drilling apparatus.

Acousto-Ultrasonic Technology for Nondestructive Evaluation of Concrete Bridge Members Strengthened by Carbon Fiber–Reinforced Polymer

2005 ◽  
Vol 1928 (1) ◽  
pp. 245-251 ◽  
Author(s):  
Mahmut Ekenel ◽  
Nestore Galati ◽  
John J. Myers ◽  
Antonio Nanni ◽  
Valery Godínez
Keyword(s):  
Carbon Fiber ◽  
Nondestructive Testing ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Ultrasonic Nondestructive Testing ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Wide Range ◽  
Cfrp Sheet ◽  
Carbon Fiber Reinforced

Carbon fiber–reinforced polymer (CFRP) composites have been used in a wide range of application areas in bridge rehabilitations because these materials are less affected by corrosive environmental conditions, are known to provide longer life, and require less maintenance. However, the quality control and quality assessment of these new rehabilitation systems should be further improved and standardized. A recent rehabilitation project that used CFRP laminates was done on a bridge in Dallas County, Missouri, by the Missouri Department of Transportation and the Center for Infrastructure Engineering Studies at the University of Missouri–Rolla. The acousto-ultrasonic nondestructive testing technology was performed to detect and image surface defects in the form of delaminations. These were intentionally formed at the CFRP sheet–concrete interface to investigate the ability of this technique. Acousto-ultrasonic nondestructive testing has shown the ability to detect and image the delaminations between CFRP sheet and concrete substrate.

scholarly journals Experimental investigation of the microstructures and tensile properties of polyacrylonitrile-based carbon fibers exposed to elevated temperatures in air

2019 ◽  
Vol 14 ◽  
pp. 155892501985001 ◽  
Author(s):  
Chenggao Li ◽  
Guijun Xian
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Elevated Temperatures ◽  
Tensile Modulus ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

The elevated temperature resistance and even fire resistance of carbon fiber-reinforced polymer composites were critical concerns in many applications. These properties of a carbon fiber-reinforced polymer depend not only on the degradation of the polymer matrix but also on that of the carbon fibers under elevated temperatures. In this study, influences of elevated temperatures (by 700°C for 30 min) in air on the mechanical properties and microstructures of a carbon fiber were investigated experimentally. It was found that the tensile strength and modulus as well as the diameters of the carbon fibers were reduced remarkably when the treatment temperatures exceeded 500°C. At the same time, the content of the structurally ordered carbonaceous components on the surface of carbon fibers and the graphite microcrystal size were reduced, while the graphite interlayer spacing ( d002) was enhanced. The deteriorated tensile modulus was attributed to the reduced graphite microcrystal size and the reduced thickness of the skin layer of the carbon fiber, while the degraded tensile strength was mainly attributed to the weakened cross-linking between the graphite planes.

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