Investigation of Bond Behavior of Polyparaphenylene Benzobisoxazole Fiber-Reinforced Cementitious Matrix-Concrete Interface

2014 ◽  
Vol 111 (5) ◽  
Author(s):  
Lesley H. Sneed ◽  
Tommaso D’Antino ◽  
Christian Carloni
Keyword(s):  
Fiber Reinforced ◽  
Bond Behavior ◽  
Cementitious Matrix ◽  
Concrete Interface

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 Analysis of the Bond Behavior of Glass, Carbon, and Steel FRCM Composites

2014 ◽  
Vol 624 ◽  
pp. 371-378 ◽  
Author(s):  
Tommaso D'Antino ◽  
Carlo Pellegrino ◽  
Christian Carloni ◽  
Lesley H. Sneed ◽  
Giorgio Giacomin
Keyword(s):  
Stress Transfer ◽  
High Strength ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Cementitious Matrix ◽  
Frp Composites ◽  
Reinforced Polymer ◽  
The Matrix ◽  
Glass Carbon ◽  
Concrete Matrix

In recent decades, the construction industry has witnessed a rapid growth of interest in strengthening and retrofitting of existing reinforced concrete (RC) and masonry structures. Fiber reinforced polymer (FRP) composites have gained great popularity, and several studies are now available in the literature on their use in strengthening and retrofit applications. Promising newly-developed composite materials are represented by the so-called fiber reinforced cementitious matrix (FRCM) composites. FRCM composites are comprised of high strength fibers embedded within a cementitious matrix that is responsible for the stress transfer between the existing structure and the strengthening material. FRCM composites are still in their infancy, and very limited results are available in the literature on RC and masonry strengthening applications. This study presents an experimental campaign conducted on different FRCM composites comprised of glass, carbon, or steel fibers embedded within two different cementitious matrices and applied to concrete prisms. The single-lap direct-shear test was used to study the stress-transfer mechanism between the FRCM composite and the concrete substrate. Two different composite bonded lengths were investigated. Debonding occurred at the matrix-fiber interface for some of the composites tested and at the concrete-matrix interface for others. This work contributes to the study of the bond behavior of FRCM composites, which represents a key issue for the effectiveness of FRCM composite strengthening.

scholarly journals Experimental Study on the Novel Interface Bond Behavior between Fiber-Reinforced Concrete and Common Concrete through 3D-DIC

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Yujie Yuan ◽  
Ming Li ◽  
Abduqader S. S. Alquraishi ◽  
Hongye Sun
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Surface Treatment ◽  
Fiber Reinforced Concrete ◽  
Surface Strain ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Interfacial Angle ◽  
Major Crack ◽  
Concrete Interface

A novel method was proposed to improve the bond behavior of new-to-old concrete interface, which was beneficial to introduce the fiber-reinforced concrete only at the old concrete interface. This study investigated the effect of the fiber addition, strength grade of new concrete, interfacial angle, and surface treatment types on the bond behavior in terms of the new-to-old concrete through the axial tensile tests. The three-dimensional digital image correlation technique (3D-DIC) and scanning electron microscope were adopted to evaluate the variation of specimen surface strain distributions and microstructure of fiber-reinforced concrete and bond interface between new-to-old concrete. The experimental results indicated that interfacial angle and surface treatment type were significantly promoted bond behaviors, while the specimen cooperating with steel fibers had the highest bond strength. Besides, the maximum strain locations obtained from 3D-DIC method were the same as the location of the specimen failure, which indicated the 3D-DIC method can be adopted to forecast the structural failure. The microcrack strain located in the major crack was decreased with the development of the major crack. Ample crystals and Ca(OH)2 were generated in the interface between the new-to-old concrete to weaken the bond strength. Moreover, this paper provided the mechanics-driven and machine learning method to predict the bond strength. This study provides a new interface bonding method for the fabricated and large span structure to effectively avoid cracking of new-to-old concrete.

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

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 967 ◽  
Author(s):  
Xinyan Guo ◽  
Shenyunhao Shu ◽  
Yilin Wang ◽  
Peiyan Huang ◽  
Jiaxiang Lin ◽  
...  
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Exposure Period ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Reinforced Polymer ◽  
Natural Exposure ◽  
Externally Bonded ◽  
Concrete Interface

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.

scholarly journals Experimental Characterization of the FRCM-Concrete Interface Bond Behavior Assisted by Digital Image Correlation

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1154
Author(s):  
Dario De Domenico ◽  
Antonino Quattrocchi ◽  
Damiano Alizzio ◽  
Roberto Montanini ◽  
Santi Urso ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Front Face ◽  
Full Field ◽  
Bond Behavior ◽  
Externally Bonded ◽  
Strengthening Technique ◽  
Concrete Interface

Digital Image Correlation (DIC) provides measurements without disturbing the specimen, which is a major advantage over contact methods. Additionally, DIC techniques provide full-field maps of response quantities like strains and displacements, unlike traditional methods that are limited to a local investigation. In this work, an experimental application of DIC is presented to investigate a problem of relevant interest in the civil engineering field, namely the interface behavior between externally bonded fabric reinforced cementitious mortar (FRCM) sheets and concrete substrate. This represents a widespread strengthening technique of existing reinforced concrete structures, but its effectiveness is strongly related to the bond behavior between composite fabric and underlying concrete. To investigate this phenomenon, a set of notched concrete beams are realized, reinforced with FRCM sheets on the bottom face, subsequently cured in different environmental conditions (humidity and temperature) and finally tested up to failure under three-point bending. Mechanical tests are carried out vis-à-vis DIC measurements using two distinct cameras simultaneously, one focused on the concrete front face and another focused on the FRCM-concrete interface. This experimental setup makes it possible to interpret the mechanical behavior and failure mode of the specimens not only from a traditional macroscopic viewpoint but also under a local perspective concerning the evolution of the strain distribution at the FRCM-concrete interface obtained by DIC in the pre- and postcracking phase.

Thermal effect on fiber reinforced polymer reinforced concrete slabs

2008 ◽  
Vol 35 (3) ◽  
pp. 312-320 ◽  
Author(s):  
A. Zaidi ◽  
R. Masmoudi
Keyword(s):  
Thermal Effect ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Concrete Slabs ◽  
Fiber Reinforced ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Frp Bar ◽  
Frp Bars ◽  
Concrete Interface

The difference between the transverse coefficients of thermal expansion of fiber reinforced polymer (FRP) bars and concrete generates radial pressure at the FRP bar – concrete interface, which induces tensile stresses within the concrete under temperature increase and, eventually, failure of the concrete cover if the confining action of concrete is insufficient. This paper presents the results of an experimental study to investigate the thermal effect on the behaviour of FRP bars and concrete cover, using concrete slab specimens reinforced with glass FRP bars and subjected to thermal loading from –30 to +80 °C. The experimental results show that failure of concrete cover was produced at temperatures varying between +50 and +60 °C for slabs having a ratio of concrete cover thickness to FRP bar diameter (c/db) less than or equal to 1.4. A ratio of c/db greater than or equal to 1.6 seems to be sufficient to avoid splitting failure of concrete cover for concrete slabs subjected to high temperatures up to +80 °C. Also, the first cracks appear in concrete at the FRP bar – concrete interface at temperatures around +40 °C. Comparison between experimental and analytical results in terms of thermal loads and thermal strains is presented.

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