Bond–slip on CFRP/GFRP-to-concrete joints subjected to moisture, salt fog and temperature cycles

Chastre, Carlos; Marreiros, Rui

doi:10.1016/j.compositesb.2013.06.015

Cited by 67 publications

(11 citation statements)

References 12 publications

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“…The fracture energy is the area under the local shear stresslocal bond slip curve, which represents the energy per unit of bonded area required to fracture the interface. It can be seen from Figure 16 that (a) the shape of these curves is similar to that observed by Nakaba et al (2001) and Silva et al (2013); (b) the ascending branches of different curves are very close to each other, implying the initial stiffness of the joint being not affected by the aging in the salt water; and (c) the difference between the descending branches of different curves is significant, meanwhile the fracture energy of the joint generally increases with the increase in the immersion time.…”

Section: Afrp-to-concrete Joint Specimenssupporting

confidence: 86%

Effects of salt solution on mechanical behaviors of aramid fiber–reinforced polymer (AFRP) sheets and AFRP-to-concrete joints

Zhang

Liu

et al. 2016

Advances in Structural Engineering

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In this article, the mechanical behaviors of four kinds of specimens (i.e. aramid fiber–reinforced polymer sheets, steel-epoxy adhesive joints, concrete cubes, and aramid fiber–reinforced polymer-to-concrete joints) were evaluated, respectively, after the specimens were immersed in 35 g/L NaCl solution for up to 360 days. Test results show that (a) except for the tensile strength of the aramid fiber–reinforced polymer sheet related to an immersion time of 45 days being 5.0% higher than that of the control sheet, the change in the sheet’s tensile strength with the immersion time is not obvious, and the tensile strength of the sheet related to an immersion time of 360 days is almost the same as that of the control sheet; (b) the effect of the salt solution on the modulus of elasticity of the aramid fiber–reinforced polymer sheet is more significant than that on the tensile strength of the sheet, and the elastic modulus of the sheet related to an immersion time of 360 days is 11.1% lower than that of the control sheet; (c) the shear strength of the steel-epoxy adhesive joint experiences severe degradation after being immersed in the salt solution, but the compressive strength of the aged concrete cube is generally larger than that of the control cube; and (d) the maximum local shear stress in the aramid fiber–reinforced polymer-to-concrete joint generally shows a fluctuating increase with the increase in the immersion time, meanwhile the fracture energy of the joint generally increases with the increase in the immersion time, but the failure pattern of the joint with shorter immersion time is different from that with longer immersion time.

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Section: Afrp-to-concrete Joint Specimenssupporting

confidence: 86%

Effects of salt solution on mechanical behaviors of aramid fiber–reinforced polymer (AFRP) sheets and AFRP-to-concrete joints

Zhang

Liu

et al. 2016

Advances in Structural Engineering

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“…Environmental reduction factors were usually adopted in codes and literatures to consider the durability under harsh environment exposure, as follow:

G_{f, env} = α \cdot G_{normalf}

where G f, env is the fracture energy under the harsh environment exposure; α is a corrective coefficient that adjusts the value of fracture energy to that determined for the wet–dry cycles and sustained loading exposure. The reduction factors for the fracture energy under dry–wet cycles were given as 1.09 in literature because the fracture energy showed significant increases for dry–wet cycles in his results, but this is obviously not in accordance with the experimental results of this paper. Therefore, the value of the coefficient given by him is not applicable to this paper and need to be determined.…”

Section: Discussion Of Fracture Energy Gfcontrasting

confidence: 61%

“…A 2‐year experimental exposure program performed by Dai et al indicated that interfacial tensile bond strength degraded after wet–dry cycling because of the formation of microcracks at the primer‐to‐concrete interface. Silva et al carried out an experimental study on the deterioration of FRP–concrete interface under dry–wet cycles with salt water. Surprisingly, the results indicated that the maximum strain in the composite and the fracture energy showed significant increases under dry–wet cycles exposure.…”

Section: Introductionmentioning

confidence: 99%

The combined effects of wet–dry cycles and sustained load on the bond behavior of FRP–concrete interface

Liang

et al. 2018

Polymer Composites

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Effective bonding between the adherents plays a key point when dealing with the retrofit of concrete structures by using fiber-reinforced polymers (FRPs). However, lack of adequate studies on the long-term performance of the bond behavior of FRP-concrete interface under harsh environments will inhibit their application in the repair of aged structures. Therefore in this study, 60 double-lap shear-bonded FRPconcrete composite specimens were designed and tested under wet-dry cycles and sustained loading. The effect of FRP type (GFRP and CFRP), wet-dry cycling times (0-360 days) and sustained loading level (0-60% of the ultimate load of the control specimen) on the failure modes, stress transfer, and local bondslip curves of the composite specimens were investigated. The experimental results showed that wet-dry cycling exposure changed the failure mode of the composite specimens from the concrete substrate to the adhesive-concrete interface, further extended the local debonding area and decreased the ultimate strains of composite specimens from 12,000 to 8,000 lE. The degree of the degradation will be further increased under the combined effect of sustained loading and wet-dry exposure. The effects of FRP type, wet-dry cycling times and sustained loading level on the fracture energy of the specimens were quantitatively analyzed. A regression model was then proposed that was able to predict the fracture energy after environment exposure with reasonable accuracy, which can provide a reference for the design of bond durability factors in relevant specifications, such as ACI 440R-08 POLYM. COMPOS., 00:000-000,

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“…Although several models [25][26][27][28][29][30][31][32][33][34][35] were proposed considering the effects of aggressive environments (such as sulphate attack, temperature change, or wet-dry cycles) on interfacial behavior, no direct models were provided for FRP-concrete interfaces after exposure to natural subtropical climates. In some models [25,26,29,30,34], the maximum stress (τ f ) and the slip (δ 1 ) corresponding to maximum stress were revised.…”

Section: Natural Exposure Effect On Bond-slip Modelsmentioning

confidence: 99%

Effect of Subtropical Natural Exposure on the Bond Behavior of FRP-Concrete Interface

et al. 2020

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Subtropical natural exposure may significantly affect the bonding behavior of fiber reinforced polymer (FRP) externally bonded to concrete. To study the effect of subtropical natural climates on the FRP-concrete interface, natural exposure tests and an analytical approach were carried out on specimens externally bonded with carbon fiber reinforced polymer (CFRP) and basalt fiber reinforced polymer (BFRP). The bilinear bond stress-slip relationships for different exposure periods were derived from the experimental results of the strengthened reinforced concrete (RC) beams. Based on these bond-slip relationships, the full-range behavior of shear stress along the bond length and debonding load can be obtained through the analytical solution. The testing and numerical results showed that subtropical natural exposure can greatly affect the bond behavior of CFRP-concrete and BFRP-concrete interfaces in the early exposure period. In the late exposure period, the bond behavior was basically stable. With the increase of exposure time, the position of maximum shear stress tended to move backward, which indicated that the behavior of the FRP-concrete interface was weakened by natural exposure. Compared to the CFRP-concrete interface, subtropical natural exposure has greater influence on the bond behavior of the BFRP-concrete interface.Polymers 2020, 12, 967 2 of 21 cycles. Under moisture cyclic condition, weakening in bond strength was observed. Cromwell [4] carried out experiments considering water exposure which showed that higher temperatures (above 60 • C) may affect the bond properties, and proposed that exposure time should exceed 10,000 h. Wan [5] found that the bond behavior of the CFRP-concrete interface degraded when the CFRP bonded specimens were submerged in water for eight weeks. Ren [6] studied the bond strength between concrete and FRP after the specimens were subjected to 98% humidity at 40 • C for 1000 h. The influence of the wet-thermal environment on the CFRP-concrete interface was significant. Ramani [7] designed a series of cyclic moisture environments including 50 • C and 100% RH, and 23 • C and 35% RH, room conditions to study the effect of moisture environments on the CFRP-concrete bond. The shear joints were exposed for five weeks before testing, and the results showed that the behavior of the CFRP-concrete bond declined by 28%. Benzarti [8] carried out pull-off tests under an accelerated aging condition (40 • C, RH 95%). It was found that moisture caused a progressive decrease in the strength of the bonded interface. Zheng [9] kept the specimens in an environmental chamber for 14 days; the RH and temperature condition were set as 95% and 60 • C, respectively. The failure mode and behavior of the CFRP-concrete interface changed compared to specimens without environmental impact.From the above literature review, it can be seen that many studies involving the interfacial durability caused by hydrothermal environment focused on the accelerated aging method [10][11][12]. However, many researchers found ...

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Bond–slip on CFRP/GFRP-to-concrete joints subjected to moisture, salt fog and temperature cycles

Cited by 67 publications

References 12 publications

Effects of salt solution on mechanical behaviors of aramid fiber–reinforced polymer (AFRP) sheets and AFRP-to-concrete joints

Effects of salt solution on mechanical behaviors of aramid fiber–reinforced polymer (AFRP) sheets and AFRP-to-concrete joints

The combined effects of wet–dry cycles and sustained load on the bond behavior of FRP–concrete interface

Effect of Subtropical Natural Exposure on the Bond Behavior of FRP-Concrete Interface

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