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On site composites-to-masonry bond evaluation in presence of rising damp and salt crystallization
Published in Claudio Modena, F. da Porto, M.R. Valluzzi, Brick and Block Masonry, 2016
G. Cardani, L. Binda, M.R. Valluzzi, P. Girardello, M. Panizza, E. Garbin, P. Casadei
The pull-off test, commonly used for a preliminary assessment of bond among layered or overlay materials (ASTM 2004), consists in applying a force, along the normal direction, to a circular or polygonal area on the surface of the composite material reinforcement, previously isolated by cutting 2-5 mm deep into the substrate. It allows evaluating the strength at the interface for loads perpendicular to the layer of application, as well as the failure mode (in the weakest cases involving the interface layer or even the fibres) (Panizza 2009). If compared with the whole aspects of the bond phenomenon, only limited information can be provided; nevertheless, this method is easily applied on site, and therefore taken in this study as reference for the evaluation of the preliminary strength in reinforced conditions
Simultaneous Incorporation of Magnesium and Fluorine Ions in Hydroxyapatite Coatings on Metallic Implant for Osseointegration and Stability
Published in Sam Zhang, Hydroxyapatite Coatings for Biomedical Applications, 2013
Yanli Cai, Sam Zhang, Soon-Eng Ong, Xianting Zeng, Wilson Wang
The pull-off test is useful in providing information on the adhesion properties at the interface of the coating and the substrate and is a relatively quantitative method for adhesion strength assessment. The adhesion strength is determined by applying a uniaxial tensile load to a cylindrical test assembly composed of one coated specimen bonded to an uncoated component. The coated and uncoated components are bonded together by the adhesive. The materials and dimensions of the uncoated component shall be the same as those of the coated specimen. After the preparation, the test assembly is placed in the grips of the tensile testing machine, and the tensile load is applied at a constant velocity until complete separation of the components is achieved [56]. Together with other testing methods of adhesion strength, the detailed bonding characteristics of the coating and the substrate can be obtained.
Evaluation of interfacial debonding of fibre-reinforced polymer using variable angle peel test
Published in Joan-Ramon Casas, Dan M. Frangopol, Jose Turmo, Bridge Safety, Maintenance, Management, Life-Cycle, Resilience and Sustainability, 2022
Issa Fowai, Martin Noël, Beatriz Martin-Perez, Leandro Sanchez
Currently, a number of tensile and shear tests exist for evaluating the interfacial bond strength of FRP strengthened concrete members (depicted in Figure 2). These traditional tests generally do not load the bond interface in a way that is representative of the service condition. The widely used pull-off test for field assessment, for instance, tests samples under pure tensile loading while laboratory specimens are typically tested using a shear lap configuration with in-plane loading. On the other hand, literature on the behavior of FRP-strengthened concrete elements under mixed mode loading remains limited (Karbhari and Engineer, 1995). Xie and Karbhari (1997) used a peel test to investigate the durability of the bond between FRP and concrete under several environmental exposure conditions. Their results obtained on the five different environmental exposures using two distinct epoxy resins shows that irrespective of the environmental condition, the level of interfacial fracture energies achieved was highly dependent on the type of resin selected and that this energy that is required to create the separation of a unit area at the bi-material interface increases with the peel angle. The authors also highlighted the effect of water absorption in both weight gain and resin swelling which reduces the performance level. The few recent existing research undertaken on this subject includes Kim & Horwitz’s (2021) work on characterization of out-of-plane peeling in combination with elevated temperature. In their project, the behavior of 54 CFRP-strengthened concrete blocks were extensively studied. The research affirms the vulnerability of the FRP-concrete interface under variable angle loading. Temperatures exceeding the glass transition temperature of the epoxy adhesive were found to cause substantial reduction in the capacity of the interface due to the softening of the interface. However, the implication of peel angles lesser than 30 or greater than 60 degrees was not studied.
Evaluation of pull-off strength for steel fibre reinforced self-compacting concrete repair overlays
Published in European Journal of Environmental and Civil Engineering, 2023
Omolbanin Arasteh Khoshbin, Rahmat Madandoust, Malek Mohammad Ranjbar
The pull-off test is used to check the bonding quality of concrete layers. This test determines the maximum vertical force required to ensure the failure in the concrete specimen’s surface or depth (depending on the method conditions). The failure position indicates the weakest zone from the adhered area between the disc and concrete to the lowest position of the borehole (if there is any). In this test, which is performed according to ASTM C1583 (ASTM C1583-04, 2004) standard, tensile strength is a prominent factor extracted based on the pull-off results. The pull-off test device is connected in such a way that an actuator attaches to the steel disc and uses it to apply a tensile load on the concrete surface. In addition, a data logger is used to store the maximum amount of force applied. The adhesive used for this experiment was selected from a two-component epoxy family.
Performance characteristics of epoxy asphalt paving material for thin orthotropic steel plate decks
Published in International Journal of Pavement Engineering, 2020
Can Chen, Wolfgang O. Eisenhut, Kreisler Lau, Ashley Buss, John Bors
To the bridge pavement technologist, orthotropic steel decks with their inherent flexibility present a particular challenge. The design of the wearing course must take into account the flexibility of the deck, pavement mixture stability, density and weight, fatigue under heavy traffic load, as well as skid characteristics. The following laboratory test methods were used to evaluate the epoxy asphalt and mixture properties: Binder direct tensile test, which gives the mechanical characterisation of binder tensile properties. ASTM D 412 – Standard Tension Test for Vulcanised Rubber and Thermoplastic Elastomers.Marshall stability test, which can assess the stability of the pavement immediately after placement and upon full cure. ASTM D 6927 – Standard Test for Marshall Stability and Flow of Asphalt Mixtures.Flexural beam fatigue test, which measures the effects of repetitive loading on the steel plate and the epoxy asphalt mix. Modified ASTM C 293 – Standard Test for Flexural Strength of Concrete (Using Simple Beam With Centre-Point Loading).Pull-off test, which measures the binder adhesive bond strength to the steel plate and gives an indirect indication of the adhesive strength of the binder to the aggregate in the mix. ASTM D 4541 – Standard Test for Pull-Off Strength of Coatings Using Portable Adhesion Testers.