scholarly journals Bond Behavior of Wet-Bonded Carbon Fiber-Reinforced Polymer-Concrete Interface Subjected to Moisture

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yiyan Lu ◽  
Tao Zhu ◽  
Shan Li ◽  
Zhenzhen Liu
Keyword(s):  
Carbon Fiber ◽  
Epoxy Resins ◽  
Concrete Structures ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Adhesive Failure ◽  
Bond Behavior ◽  
Reinforced Polymer ◽  
Concrete Interface

The use of carbon fiber-reinforced polymer (CFRP) composite materials to strengthen concrete structures has become popular in coastal regions with high humidity levels. However, many concrete structures in these places remain wet as a result of tides and wave-splashing, so they cannot be completely dried before repair. Therefore, it is vital to investigate the effects of moisture on the initial and long-term bond behavior between CFRP and wet concrete. This research assesses the effects of moisture (i) during CFRP application and (ii) throughout the service life. Before CFRP bonding, the concrete blocks are preconditioned with a water content of 4.73% (termed “wet-bonding”). Three different epoxy resins are applied to study the bond performance of the CFRP-concrete interface when subjected to moisture (95% relative humidity). A total of 45 double-lap shear specimens were tested at the beginning of exposure and again after 1, 3, 6, and 12 months. All specimens with normal epoxy resins exhibited adhesive failure. The failure mode of specimens with hydrophobic epoxy resin changed from cohesive failure to mixed cohesive/adhesive failure and to adhesive failure according to the duration of exposure. Under moisture conditioning, the maximum shear stress (τmax) and corresponding slip (smax) of the bond-slip curve first increased and then decreased or fluctuated over time. The same tendency was seen in the ultimate strain transmitted to the CFRP sheet, the interfacial fracture energy (Gf), and the ultimate load (Pu). Analytical models of Gf and Pu for the CFRP-concrete interface under moisture conditioning are presented.

Experimental study on the behavior of carbon fiber reinforced polymer sheets bonded to concrete

2006 ◽  
Vol 33 (11) ◽  
pp. 1438-1449 ◽  
Author(s):  
Ayman S Kamel ◽  
Alaa E Elwi ◽  
Roger J.J Cheng
Keyword(s):  
Carbon Fiber ◽  
Failure Mechanism ◽  
Test Method ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

This paper presents a study on the interfacial behavior of carbon fiber reinforced polymer (CFRP) sheets when applied to concrete members as external reinforcement. Two bond test methods that are detailed in the paper were used in separate test series to study the bond behavior and failure mechanism of CFRP sheets bonded to concrete. A modified push-apart test method was proposed and tested. It was concluded that there existed an effective length beyond which there will be no increase in the ultimate capacity of the joint. An experimental test method to determine the effective bond length was also proposed and tested. The strains at the edge of the CFRP sheets are consistently higher than those at the center. The anchorage requirements for the CFRP sheets were also investigated in this study. Anchor sheets placed at 90° to the primary test sheets and bonded underneath the tested sheet showed better or equivalent overall bond behavior compared with those bonded on top of the tested sheet. The distance at which the anchor sheet is placed from the crack does not appear to change the bond behavior.Key words: bond, concrete, debonding, failure mechanism, carbon fiber reinforced polymer (CFRP) sheets, anchor sheets.

scholarly journals Flexural and Shear Strain Characteristics of Carbon Fiber Reinforced Polymer Composite Adhered to a Concrete Surface

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2596 ◽  
Author(s):  
Hisham Jahangir Qureshi ◽  
Muhammad Umair Saleem
Keyword(s):  
Carbon Fiber ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Shear Stresses ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

The use of Fiber Reinforced Polymer (FRP) composites for strengthening concrete structures has gained a lot of popularity in the past couple of decades. The major issue in the retrofitting of concrete structures with FRP is the accurate evaluation of flexural and shear strains of polymer composites at the bonding interface of epoxy and concrete. To address it, a comprehensive experimental study was planned and carbon fiber reinforced polymer (CFRP) composite was applied on the concrete surface with the help of adhesives. CFRP was used as an external mounted flexural and shear reinforcement to strengthen the beams. Flexural load tests were performed on a group of eight reinforced concrete beams. These beams were strengthened in flexural and shear by different reinforcement ratios of CFRP. The strain gauges were applied on the surface of concrete and CFRP strips to assess the strain of both CFRP and concrete under flexural and shear stresses. The resulting test data is presented in the form of load–deformation and strain values. It was found that the values of strains transferred to the FRP through the concrete are highly dependent on the surface tensile properties of concrete and debonding strength of the adhesive. The test results clearly indicated that the strength increment in flexural members is highly dependent on strain values of the CFRP.

scholarly journals Bond Performance of Carbon Fiber-Reinforced Polymer Bar with Dual Functions of Reinforcement and Cathodic Protection for Reinforced Concrete Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Yingwu Zhou ◽  
Lili Sui ◽  
Feng Xing ◽  
Xiaoxu Huang ◽  
Yaowei Zheng ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Cathodic Protection ◽  
Concrete Structures ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Reinforced Concrete Structures ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Steel Bar

The dual function of a carbon fiber-reinforced polymer (CFRP) bar working as reinforcement and impressed current cathodic protection (ICCP) anode for reinforced concrete structures has been proposed and researched in this paper. The ICCP tests with different current densities and polarization durations were first conducted for the concrete with high chloride content. After the ICCP application, pull out tests were then performed to investigate the bond behaviors of CFRP bars. Experimental results have shown the effectiveness of the new-type ICCP system with the CFRP bar as the anode on corrosion protection. The ICCP system provided electrons to the steel bar continuously and brought the potential of the steel bar down to the immunity region. Under the anodic polarization with a large current density of 100 mA/m2, the CFRP bar-concrete interface presented acidification and the chemical adhesion on the interface was decreased significantly. However, for cases in the experiment, the ICCP application had an insignificant influence on the ultimate bond strength.

Debonding Strain Characteristics of Carbon Fiber Reinforced Polymer Composite Adhered to the Concrete Surface

2018 ◽  
Author(s):  
Hisham Jahangir Qureshi ◽  
Muhammad Umair Saleem
Keyword(s):  
Carbon Fiber ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Shear Stresses ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

The use of Fiber Reinforced Polymer (FRP) composites for strengthening concrete structures has gained a lot of popularity in the past couple of decades. The major issue in the retrofitting of concrete structures with FRP is the accurate evaluation of debonding flexural strain of polymer composites at the bonding interface of epoxy and concrete. In order to address it, a comprehensive experimental study was planned and carbon fiber reinforced polymer (CFRP) composite was applied on the concrete surface with the help of adhesives. CFRP was used as an external mounted flexural and shear reinforcement to strengthen the beams. Flexural load test was performed on a group of eight reinforced concrete beams. These beams were strengthened in flexure and shear by different reinforcement ratios of CFRP. The strain gauges were applied on the surface of concrete and CFRP strips to assess the debonding strain of both CFRP and concrete under flexural and shear stresses. The resulting tests data is presented in the form of load –deformation and strain values. It has been found that the values of strains transferred to the FRP through the concrete are highly dependent on the surface tensile properties of concrete and debonding strength of the adhesive. The test results have clearly indicated that the strength increment in flexural members is highly dependent on debonding strain values of FRP from the concrete surface.

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