Lap Shear Tests Research Articles

A REVIEW ON BOND PERFORMANCE OF FRP-CONCRETE SYSTEM AT VARIOUS ENVIRONMENTAL CONDITIONS

Strengthening concrete structures with Fibre Reinforced Polymer (FRP) is one of the most commonly used technique to repair and rehabilitate concrete members due to the advanced properties of FRP over other conventional materials such as steel plates. The required performance of FRP-concrete system is linked to achieve proper bond between FRP and concrete substrates that as exposed to different environmental conditions. In the current paper, a review is conducted to highlight the most reported work by other researchers regarding the bond behavior of concrete members that strengthened with FRP in shear-tension and exposed to temperature-based conditions and compared with ambient conditions. The current review focused on the conducted work on FRP/concrete system that strengthened with two different installation techniques (externally bonding (ES) and near–Surface mounted (NSM)) using two different bonding agents (epoxy-based adhesive (EBA) and cement-based adhesive (CBA)) with and without modification. The adoption of two specific bond test procedures (adhesion and single lap shear tests) at ambient conditions and temperature-based conditions was also reviewed intensively to clarify the advantages and drawbacks associated with each test. Some reported findings by others in conducting bond test methods for different FRP/concrete systems were highlighted as well to address the gap in knowledge and the need for further research in this regard.

Synthesis and properties of an efficient self-healing material based on Eucommia ulmoides gum

The unique molecular chain and aggregation structures of Eucommia ulmoides gum (EUG) lead to unique mechanical and thermal behavior. By regulating the microstructure of EUG via chemical reactions, changes in the mechanical and thermal behavior as well as the addition of specific functionalities of EUG can be achieved. Herein, we report a simple method to prepare intrinsic, autonomous, low-temperature self-healing materials by introducing pendent polyol moieties onto the chain of epoxidized EUG (EEUG). The relationship between the microstructure and properties of the resultant hydroxyl-functionalized EEUG (FEEUG) was analyzed by Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), tensile tests, and lap shear tests. As the modification degree of FEEUG increased, the mechanical behavior of FEEUG gradually changed from plastic to elastic and then to viscous, and the material showed highly efficient self-healing behavior. The self-healing efficiency was 77.8 % after 1 h of free contact at 30 °C and reached up to 90.2 % after 4 h. During five repeated lap shear tests, the adhesive strength of FEEUG28.6 (sample with a modification degree of 28.6 mol. %) decreased by only 10.9 %. The specific high chain mobility due to the diffusion and randomization of EUG at low temperatures and the reversible recovery of hydrogen bonds are believed to be the main causes for this phenomenon.

Interface contact behavior of 3D printed porous surfaces

When a 3D printed implant integrates a thin surface lattice, the geometry of this porous region controls the bone-implant interface, affecting both short-term implant stability and long-term osseointegration. In intervertebral devices, for example, high expulsion resistance and propensity to subside are imperative in reducing implant migration and loss of disc height. Moreover, the shear strength of the porous-solid metal interface is critical to prevent metal-to-metal decohesion prior to and after osseointegration. While lap shear and subsidence tests are both governed by ASTM standards, expulsion testing is not standardized, and the tradeoffs in the potential implant failure modes have not been thoroughly investigated to find an optimal porosity satisfactory in all three performance tests. In this multi parameter study, we perform a series of experiments on 3D printed porous gyroid surfaces to understand the interplays and inherent tradeoffs between porosity, expulsion resistance, propensity to subside, and porous layer strength. Porosity was the only significant factor affecting expulsion, subsidence, and ultimate shear strength. As porosity increased, expulsion resistance of the surface porosity sample increased, resulting in samples that are harder to push out of a constrained bony cavity; however, shear strength and propensity to subside both decreased, resulting in a weaker metal-to-metal porous layer adhesion and equivalent penetration into the Sawbone surface at lower forces. Within the error of the measurements, the 6 × 6 × 6 0.75 mm wall thickness gyroid (65% modeled porosity and 62% measured porosity) design presented the best overall performance characteristics.

Assessment of Composite Aluminum Adhesive Joints Using Digital Image Correlation

Traditional nondestructive evaluation (NDE) methods present significant challenges to detecting and characterizing kissing or weak bonds in adhesively bonded structures. These kissing or weak bonds also cannot transmit shear stresses or handle complex loading modes and, if not detected, can present a significant threat to the structural integrity of the components or systems. This paper demonstrates the digital image correlation (DIC) technique for evaluating adhesively bonded dissimilar materials joints subjected to kissing or weak bonds. The study employed four adhesively bonded carbon fiber reinforced plastics and aluminum (CFRP-Al) lap-shear test coupons with varied bond quality (i.e., with no contamination and three simulated kissing bond defects). The novelty of the approach presented in this paper was that this technique could detect and demonstrate changes in the normal strain (εyy) contour map of the contaminated specimens at relatively lower load levels. This load level corresponds to 15% of the failure load for the silicone and hydraulic oil contaminated sample and around 30% for the polyvinyl alcohol (PVA) contaminated sample. In addition, higher compressive strains along the overlap edges were observed in the strain map for the single lap joints due to the higher peeling stresses of the adherend and the stress concentration at the edges of an adhesively bonded joint.

Interfacial carbon fiber–matrix interactions in thermosetting composites volumetrically cured by electromagnetic fields

We present a novel out-of-oven method for curing carbon fiber reinforced composites (CFRCs) using radio frequency (RF) fields and assess the effects of fiber heating on the fiber–matrix interfacial properties. In this volumetric heating setup, thermal energy is generated by the carbon fibers interacting with the RF fields (1–200 MHz range) and drives the crosslinking reaction in the epoxy. To study the effect of RF heating and curing on the interfacial properties, we processed composites with carbon fibers embedded in thermosetting resin at varying target curing temperatures and tested these composites using nanoindentation and lap-shear tests that show comparable behavior to conventional oven-cured composites. Experimental characterization is coupled with finite element analysis and reactive molecular dynamics (ReaxFF) simulations to investigate and understand the interfacial properties. This investigation indicates that electromagnetic heating can be used to cure CFRCs rapidly without degrading the fiber–matrix interface.

Comprehensive Weldability Criterion for Magnetic Pulse Welding of Dissimilar Materials

Despite its exceptional ability to join dissimilar materials and environmental friendliness, several challenges must be addressed in magnetic pulse welding (MPW). The conventional weldability criterion (i.e., minimum impact velocity) is analytically calculated as a function of material properties without considering the geometry of electromagnetic coil, electrical and physical parameters, making the minimum impact velocity a necessary but not sufficient condition for a sound MPW joint. A new weldability criterion, namely effective impact velocity, is proposed, which overcomes the conventional weldability criterion’s limitations. The effective impact velocity can be inversely modelled to identify shop-floor relevant process parameters and it eliminates the need to fabricate several coils in the process and product proving stages. The proposed approach is demonstrated by a case study on tubular welding of Aluminium and SS304. The weld’s soundness produced with computed process parameters was corroborated by experimental observations on lap shear tests, hardness measurements, optical and scanning electron microscopy, and surface energy dispersive spectroscopy mapping. This investigation is expected to pave the way for developing the process window for MPW of several material combinations, with high cost and time savings.

Electrically Conductive Adhesive Based on Thermoplastic Hot Melt Copolyamide and Multi-Walled Carbon Nanotubes.

For the bonding of the lightweight composite parts, it is desired to apply electrically conductive adhesive to maintain the ability to shield electromagnetic interference. Among various solvent-based adhesives, there is a new group of thermoplastic hot melt adhesives that are easy to use, solidify quickly, and are environment-friendly. To make them electrically conductive, a copolyamide-based hot melt adhesive was mixed with 5 and 10 wt% of carbon nanotubes using a melt-blending process. Well-dispersed nanotubes, observed by a high-resolution scanning microscope, led to the formation of a percolated network at both concentrations. It resulted in the electrical conductivity of 3.38 S/m achieved for 10 wt% with a bonding strength of 4.8 MPa examined by a lap shear test. Compared to neat copolyamide, Young’s modulus increased up to 0.6 GPa and tensile strength up to 30.4 MPa. The carbon nanotubes improved the thermal stability of 20 °C and shifted the glass transition of 10 °C to a higher value. The very low viscosity of the neat adhesive increased about 5–6 orders of magnitude at both concentrations, even at elevated temperatures. With a simultaneous growth in storage and loss modulus this indicates the strong interactions between polymer and carbon nanotubes.

Role of surface structures on long term stability of adhesive joints between Ti–15V–3Cr–3Sn–3Al and polyether-ether-ketone

Adhesive bonding of similar and dissimilar materials is a key enabler for lightweight design in the automobile as well as aerospace industries. The strength and durability of adhesive metal-polymer joints in humid atmospheres depends strongly on surface pretreatments. Different pretreatments of Ti–15V–3Cr–3Sn–3Al (Ti15-3) for joining to polyether-ether-ketone (PEEK) were investigated in order to optimize the joint properties and elucidate underlying bonding mechanisms. Micro- and nanostructured surfaces were created with laser and chemical pretreatments and characterized with microscopy and X-ray photoelectron spectroscopy (XPS). The mechanical performance of the joints was analyzed with single lap shear tests in both the initial condition and after hydrothermal aging. Without significant structuring only physico-chemical interactions were present that accounted for strengths of up to 45 MPa. In the presence of micro- or nanostructures that add interlocking possibilities to the bonding, a maximum strength of 74 MPa was obtained. Hydrothermal aging resulted in poor residual strengths for samples without structuring, showing that humidity strongly degraded physico-chemical bonding. High aging resistance was particularly reached for laser pretreated specimens with an open-porous nanostructure. By comparing the different surfaces, it was found that (i) nanostructuring has a bigger impact on the aging resistance than microstructuring, and (ii) aging can be assigned mainly to weakening of physico-chemical bonding. Therefore, it can be deduced that nanomechanical interlocking is a key for producing long-term stable Ti15-3/PEEK joints.

Laser-assisted joining of carbon fiber reinforced polyetherketoneketone thermoplastic composite laminates

Carbon-fiber-reinforced thermoplastic (CFRTP) materials have drawn considerable interest owing to their high strength-to-weight ratio. Laser joining technologies have been reported to join CFRTP to metals or plastic materials. However, the direct laser joining of CFRTP/CFRTP is challenging. Herein, we demonstrated the feasibility of laser direct joining of 2.2-mm-thick CFRTP/CFRTP by laser heat conduction. A thulium fiber laser (1940 nm) was used under the optimal joining conditions of 20 W power (beam diameter = 5.5 mm, approximately) and 3 min laser irradiation time. We observed that an increase in the laser irradiation spots per unit area results in a higher joining strength. The joining strengths of carbon fiber (CF)-polyetherketoneketone (PEKK)/CF-PEKK composites were evaluated by single lap shear tests, and the highest average interlaminar shear strength result was 30.9 MPa. Our study indicates that the laser-assisted joining of CF-PEKK/CF-PEKK laminates is viable and worthy of further exploration for industrial applications.

The effect of weak boundary layers on adhesion properties of laser pretreated aluminum alloy EN-AW 6082 surfaces

This study investigates the influence of the laser ablation regimes and the material removal mechanisms on the morphologies, topographies, and chemistries of laser formed surface structures on the aluminum alloy EN-AW 6082. The characteristics of these surface structures are correlated to the adhesion and durability of joints bonded adhesively with PA6. X-ray photoelectron spectroscopy showed that the chosen laser ablation regimes have almost no influence on surface chemistries while microscopic analysis indicated that the surface structures are affected significantly. The adhesion properties and durability of the adhesively bonded joints studied by single lap shear and aging tests are strongly affected by the ablation regimes. Optimal initial shear strengths and aging resistances were obtained for a single step laser treatment with parameters corresponding to the melt displacement mode, while multi-step treatments provided no further benefits. A failure analysis revealed that the micro- and nanostructures developed in melt ejection regime of laser ablation can act as weak boundary layers (WBLs) on metal substrates and affect adversely the adhesion and durability of the joints.

Enhanced mechanical, thermal and adhesion properties of addition cured polydimethylsiloxane nanocomposite adhesives

The reinforcement of elastomeric polydimethylsiloxanes (PDMS) with carbon-based fillers and silica has gained much attention over the last few decades due to the inherent stability of the fillers which improves the physical and mechanical properties of the polymer nanocomposites. We report herein the preparation of an addition cured V-PDMS (vinyl-terminated PDMS) nanocomposite using CNT (carbon nanotube) and Aerosil COK 84 (mixed silica and alumina) as fillers. The influence of the fillers on the morphology, mechanical properties, thermal stability, thermal conductivity, and adhesive strength of these addition cured PDMS nanocomposites was studied in detail. It was observed that the tensile strength and thermal stability of the nanocomposites were enhanced upon the addition of fillers. The higher thermal conductivity of the CNT reinforced nanocomposites has potential application in heat sealing materials. The adhesive strength was studied by conducting a lap shear test on both mild steel and aluminum substrates and the adhesive strength was found to be higher for the mild steel substrate.

Structural Response of Wire Arc Additively Manufactured Steel Bolted Connections under Single Shear

AbstractAn experimental investigation into the structural performance of wire arc additively manufactured (WAAM) steel single‐lap shear bolted connections is presented in this paper. Sixty specimens of different thicknesses, printing strategies and geometric features, including end distances and plate widths, were manufactured using steel wire of a nominal yield strength of 420 MPa and subjected to single shear lap tests. The test results are analysed while the observed failure modes, featuring shear‐out, net section tension fracture, end‐splitting, localised tearing and curl‐bearing failure, are discussed. Digital image correlation (DIC) was used for detailed monitoring and visualisation of the surface strain fields that developed during testing, providing valuable insight into the developed failure mechanisms. The experimental results, which generally followed the anticipated trends, were used to assess the applicability of current design specifications developed for conventional steel bolted connections to WAAM steel bolted connections. It was found that both the cold‐formed steel specifications (AISI S100 and AS/NZS 4600) and the structural steel specifications (AISC 360 and EN 1993‐1) yield considerable overestimations or underestimations of the test capacities, depending on the specimen geometry. Further research is underway to underpin the development of improved design provisions.

Lap-shear strength and fracture behavior of CFRP/3D-printed titanium alloy adhesive joint prepared by hot-press-aided co-bonding

Multimaterial structures comprising carbon fiber reinforced plastics (CFRPs) and titanium alloys can be widely utilized in the aerospace and automotive industries to achieve optimal weight reduction and reliable structures. In this study, three-dimensional-printed titanium (3DP-Ti) adherends prepared using selective laser melting were co-bonded with woven-fabric carbon fiber reinforced phenolic matrix composite by hot pressing. Upon controlling the scanning speed and path, the 3DP-Ti adherends were prepared with various porosities and macrostructures on their surfaces, and the influences of these surface structures on the lap-shear strengths and fracture morphologies of the 3DP-Ti adherends were investigated. The lap-shear tests of the lap-shear joints with flat 3DP-Ti and pyramidal-macrostructured 3DP-Ti displayed the cohesive failure of the phenolic resin matrix. In contrast, the specimen with cylindrical macrostructure exhibited CFRP fracture and delivered the highest bond strength of 20.6 MPa, which was 18–64% greater than the strength of the lap-shear joint with the conventional Ti alloy plate and 3DP-Ti adherends with flat surface and pyramidal macrostructure. The major possible mechanisms behind the failure mode transition and the highest bond strength included the mechanical interlocking between the cylindrical macrostructure and CFRP.

Behaviour of EBRIG CFRP sheet-concrete joint: Comparative assessment with EBR and EBROG methods

• This study was the first attempt to evaluate the behavior of EBRIG FRP-concrete joints in comparison with EBR and EBROG joints. • A novel setup was developed to prepare the EBRIG specimens and carry the lap-shear tests on them. • The results including bond strength, failure modes, and other bond properties, confirmed the significant superiority of EBRIG installation method over the EBR and EBROG ones. • PIV technique was adopted to achieve the deformations fields and other bond properties. Grooving methods (GM) have remarkably shown higher efficiency than Externally Bonded Reinforcement (EBR) in anchoring the Fiber Reinforced Polymers (FRP) used for flexural retrofitting concrete structures. They are categorized into two types: Externally Bonded Reinforcement on Grooves (EBROG) and Externally Bonded Reinforcement In Grooves (EBRIG). The behavior of the EBR and EBROG joints were evaluated in many studies, but the behavior of EBRIG ones has not been assessed yet, and the present study is the first attempt to achieve the above aim. Accordingly, 12 concrete prisms were strengthened using one or two-layer of Carbon FRP (CFRP) sheets bonded via the EBR, EBROG, and EBRIG methods and then tested by a single lap-shear setup. In addition to evaluating bond strengths and failure modes, the bond behavior, including load-slip and shear stress-slip curves, and the slip, strain, and shear stress longitudinal profiles were acquired by Particle Image Velocimetry (PIV) technique. The results indicated substantial enhancement in the bond properties of specimens strengthened using grooving methods over the EBR. Besides, the EBRIG joint revealed a higher performance compared to the EBROG joint. For instance, applying the EBRIG method instead of EBROG led to 39% and 120% bond strength enhancement for one and two-layer FRP reinforced specimens, respectively. Additionally, all the EBROG joints failed due to cohesive debonding, whereas FRP sheets either ruptured or deeply debonded in the EBRIG joints reinforced with one or two layers of FRP.

Mechanical properties of laminated bamboo composite as a sustainable green material for fishing vessel: Correlation of layer configuration in various mechanical tests

Abstract With the increased emphasis on the need to use recyclable bio-based materials and a better understanding of the mechanical properties of laminated bamboo, there is currently a great deal of interest in developing a new generation of low-cost bamboo-based composites for use in fishing vessels. Laminated bamboo composites (LBCs) comprised of Apus bamboo (Gigantochloa apus) and fibreglass mats were investigated to obtain the mechanical characteristics. The LBC with 45°/−45° cross-fibre directions combined with chopped strand mat fibreglass was developed under different layers and mass fractions with the same composite thickness. The influence of different numbers of laminated bamboo layers (3–7 layers) on several mechanical testings, including impact tests using ASTM D256, bending tests using ASTM D7264, tensile tests using ASTM D3039, V-notched beam test using ASTM D7078, and lap shear tests using ASTM D5868 standard, were carried out. The result showed that the strategy in improving the strength properties of LBCs could be achieved by using a thinner bamboo lamina with a higher number of bamboo layers. It was found that bamboo composites with 7 layers with a higher epoxy mass matrix had superior mechanical properties than those with 3 and 5 layers at the same thickness. Another finding revealed that adding fibreglass mat to current LBCs improved mechanical properties compared to previous research, explicitly bending strength increased by about 4.02–7.56% and tensile strength in the range of 12.44–17.73%. It can be found that only specimen with 7 layers fulfils the Indonesian Bureau Classification’s bending and tensile strength threshold.

Hybrid Ensemble Model for Predicting the Strength of FRP Laminates Bonded to the Concrete.

The goal of this work was to use a hybrid ensemble machine learning approach to estimate the interfacial bond strength (IFB) of fibre-reinforced polymer laminates (FRPL) bonded to the concrete using the results of a single shear-lap test. A database comprising 136 data was used to train and validate six standalone machine learning models, namely, artificial neural network (ANN), extreme machine learning (ELM), the group method of data handling (GMDH), multivariate adaptive regression splines (MARS), least square-support vector machine (LSSVM), and Gaussian process regression (GPR). The hybrid ensemble (HENS) model was subsequently built, employing the combined and trained predicted outputs of the ANN, ELM, GMDH, MARS, LSSVM, and GPR models. In comparison with the standalone models employed in the current investigation, it was observed that the suggested HENS model generated superior predicted accuracy with R2 (training = 0.9783, testing = 0.9287), VAF (training = 97.83, testing = 92.87), RMSE (training = 0.0300, testing = 0.0613), and MAE (training = 0.0212, testing = 0.0443). Using the training and testing dataset to assess the predictive performance of all models for IFB prediction, it was discovered that the HENS model had the greatest predictive accuracy throughout both stages with an R2 of 0.9663. According to the findings of the experiments, the newly developed HENS model has a great deal of promise to be a fresh approach to deal with the overfitting problems of CML models and thus may be utilised to forecast the IFB of FRPL.

Safety and performance of surgical adhesives.

BackgroundTissue adhesives are an alternative to conventional surgical sutures to reduce the time and cost of wound closure and to improve patient comfort. The use of tissue adhesives does not require any subsequent intervention and significantly lowers the volume and rate of blood loss, and reduces the need for transfusions during and after surgery. However, based on their formulation, tissue adhesives’ safety profile and functional properties may differ. Therefore, this study aimed to evaluate the basic safety and performance of NE’X Glue® Surgical Sealant, BioGlue® Surgical Sealant, and PREVELEAKTM Surgical Sealant in vitro.MethodsThe basic safety of commercially available tissue adhesives was evaluated using MEM elution assay according to ISO 10993–5 and endotoxin level according to 85. USP. The in vitro performance was evaluated using lap-shear by tension loading test, burst strength test, degradation, and swelling assays.ResultsNE’X Glue®, BioGlue®, and PREVELEAKTM did not cause cytotoxicity in MEM elution assay. All surgical adhesives are below the general limit of endotoxin contamination of 20 EU/device. NE’X Glue® and BioGlue® showed the highest and comparable strength properties in lap shear and burst strength tests compared to PREVELEAKTM. NE’X Glue® and PREVELEAKTM are characterized by lower degradation potential than BioGlue®. PREVELEAKTM is characterized by the highest swelling when compared to NE’X Glue® and BioGlue®.ConclusionsNE’X Glue® is most versatile in terms of functional properties while maintaining the same safety profile as BioGlue® and PREVELEAKTM.

Multifunctional MEN-Doped Adhesives: Strengthening, Bond Quality Evaluation, and Variations in Magnetic Signal with Environmental Exposure

Adhesive bonding of polymer matrix composites offers various advantages over traditional fasteners, such as a uniform stress state, reduced weight, and delay of composite delamination. However, adhesive bonding has limited implementation due to challenges in the prediction of durability. This work introduces a new method to monitor an adhesively bonded composite joint by dispersing magneto-electric nanoparticles (MENs) into the polymer precursor and monitoring changes in their surface charge density by evaluating the output magnetic signal under an applied magnetic field. Real-time monitoring of the curing process of a polymer adhesive was performed and corroborated via thermal analysis and mechanical testing. Lap shear and end notch flexure testing showed that adding 1 vol% MENs led to a ~23% increase in shear strength and a ~12% increase in mode II critical energy release rates compared to the undoped adhesive. Adding 5 vol% MENs also increased the adhesive’s peak tensile stress by ~8%. Strengthening mechanisms of the doped adhesive were monitored using in situ electron microscopy. A correlation between water ingression and a change in the magnetic moment was observed. Results show the MENs’ potential as a structural health-monitoring tool for a wide range of materials and applications.

Friction stir spot welding of dissimilar quality galvanized steel sheets meant for automotive applications using a consumable sheet

Friction stir spot welding (FSSW) is a solid-state spot-joining method used to join aluminum alloys to other materials for fabricating lightweight components. However, the FSSW tool experiences wear and tear during the spot welding of steel-grade sheets. To overcome this problem, in the present work, friction stir spot welding using a consumable sheet (FSSW-C) is proposed, in which the tool does not contact the steel sheet during the entire welding cycle. The main aim of this study is to investigate the application of FSSW-C to dissimilar galvanized steel sheets at various rotational speeds via lap shear tests and examination of the joint macro/microstructures. The lap shear performance was also compared to that of the Self Pierce Rivet (SPR) joint. The results revealed that galvanized steel sheets were successfully spot welded using FSSW-C with a lap shear fracture load of 1.5 kN–2.2 kN, which is approximately 50% of that of SPR joints. The microstructures revealed important features, including microstructural zones such as the stir zone, thermomechanically-affected zone, and heat-affected zone. Intermetallic compound formation was not observed at the joint interface. As the rotational speed increased, the axial force and torque decreased, whereas the temperature increased during FSSW-C. The energy generated increased with an increase in the rotational speed and was significantly different when compared to the data for conventional FSSW.

Fracture characteristics and stress transfer length of CFRP-concrete bond under field conditioning

To estimate the actual durability of CFRP-concrete bond, an investigation into bond behavior of the interface between CFRP and concrete under field conditioning (FC) in a subtropical area is presented. Single lap-shear tests were conducted on CFRP-concrete specimens subjected to FC for up to 360 days. Bond slip law and fracture characteristics were evaluated using a generalized approach based on the experimental load-displacement curves. The results show that the local bond strength decreased by 30% in the initial 90 days and a 10% recovery appeared after additional 270 days, while the interfacial fracture energy showed a 30% increase after 360 days. Analytical modeling incorporating the evaluated bond slip law was performed and the effect of FC on the stress transfer was revealed. The effective bond length increased by 50% throughout FC. Besides, it can be found that an electromechanical impedance method (EMI) via the use of PZTs was able to monitor the CFRP-concrete interface during single lap-shear tests, and the monitoring results can indicate the bond deterioration.