Papers by Keyword: Bond Strength

Abstract: The degradation behavior of adhesion between cycloaliphatic epoxy resin and copper under high temperature and high humidity conditions was investigated. The Cu/resin joints were aged at 175°C and at 85°C in 85% R. H. The degradation behavior of the joint interface was analyzed by tensile tests and Fourier infrared transform spectroscopy (FT-IR). As a result, it was confirmed that the adhesion strength was retained after aging at 175°C for 1000 h, while it decreased with an increase in the aging time by aging at 85°C in 85% R. H. Furthermore, the interfacial fracture mode increased with aging at 175°C. In contrast, cohesive fracture was the main fracture mode and hardly changed by aging at 85°C in 85% R. H. The FT-IR analysis results showed that the peak intensity of the carbonyl group increases and that of the methylene group decreases by aging at 175°C. The result indicates that the resin was oxidized. Moreover, the peak intensities of carboxy and hydroxyl groups increased and that of ester groups decreased by aging at 85°C in 85% R. H. The results suggest that ester groups may be hydrolyzed due to aging and thus the adhesion is degraded.

Abstract: The problem of corrosion in reinforced concrete infrastructure can be addressed by using fibre-reinforced polymer (FRP) bars, since they are a feasible alternative due to their non-corrosive nature. Basalt fibre-reinforced polymer (BFRP) bars have recently gained attention as a possible substitute for both of these materials because they are less expensive than Carbon Fibre-Reinforced Polymer (CFRP) and have greater tensile strength than Glass Fibre-Reinforced Polymer (GFRP). While considerable research has been conducted on CFRP bars and GFRP bars, studies on BFRP are limited, hindering its incorporation into design guidelines. Therefore, in this study, bond behaviour of BFRP bars in concrete is experimentally evaluated. This study concludes that although BFRP bar shows more slip than steel bar, its bond strength is comparable to that of steel bar. It is also found that the bond strength and maximum slippage reduced with an increase in the bars' diameter and embedment length. Furthermore, the bond strength improves as the cover increases. Furthermore, bond strength equations as proposed by ACI 440.1 R15, CSA S806-02, and CSA S6-06 underestimated the experimental bond strength.

Abstract: Boron Nitride (BN) filler was modified by an ion beam surface treatment to enhance dispersibility to polar solvent and bond strength with epoxy. Surface treatment of the fillers was conducted by Ion Assisted Reaction (IAR), in which Ar⁺ ion beam is irradiated on the filler surface with energy of 1keV, dose varied from 1x10¹⁴ ~ 5x10¹⁶ Ar⁺ ions/cm² by using Cold Hollow Cathode type ion source and oxygen gas 5-10ml/sec. After the surface treatment, the BN powder were spontaneously dispersed into polar solvent in a visual observation which means the modified surface was changed from hydrophobic to hydrophilic, and the powder were easily mixed with a viscous epoxy resin until 40wt% without thinner (a gelation phenomenon with easy blending into the epoxy resin), but the untreated powder exhibits difficulty in mixing with epoxy resin without the thinner. XPS analysis showed oxygen functional groups (B-ON, BN, etc.) were formed on the surface of BN. It was confirmed the surface modification has a high filling ability of the BN filler with binder and better adhesion with epoxy resin compared to the untreated BN filler.

Abstract: Lately, considerable efforts have been directed towards investigating the practicality of using coarse recycled concrete aggregate as a potential substitute for natural coarse aggregate (NCA) in concrete construction. Research has shown that both the proportion of replacement and the properties of recycled aggregates play a significant role in affecting the tensile strength, compressive strength, and bonding characteristics of concrete. In certain cases, recycled aggregate concrete exhibits lesser mechanical properties when compared to concrete made with normal aggregates. The current study investigated the performance of Sika AnchorFix-1 to enhance the bond strength between steel bars and recycled aggregate concrete. The findings suggest that Sika AnchorFix-1 successfully prevented the concrete rupture in the case of concrete with recycled concrete aggregates, whereas concrete rupture could not be prevented in the case of concrete with recycled brick aggregates. Hence, a lower bond strength was obtained for specimens with recycled bricks aggregates than specimens with recycled concrete aggregates.

Abstract: This research experimentally investigated the bond strength of recycled aggregate concrete containing high volume ground granulated blast-furnace slag (GGBFS). Concrete mixtures made with 0%, 15%, 45% and 75% replacement of cement with GGBFS were prepared. Water-to-binder ratios ranged from 0.30 to 0.50. The fresh properties, compressive strength and pullout bond strength of concrete were measured and presented. Test results shows that the compressive strength and bond strength of concrete containing GGBFS were superior to the concrete without GGBFS at all ages. In addition, the bond strength of the recycled aggregate concrete containing high volume GGBFS (75% cement replacement) could exceed that of natural aggregate concrete without GGBFS. This result shows that it is feasible for applying recycled aggregate concrete incorporating high volume GGBFS in concrete constructions.

Abstract: The adhesive strength and degradation behavior of the Al/resin interface was investigated under high temperature and high humidity conditions. The adhesive strength of the joint without aging was approximately 14 MPa. The value is the same as the Cu/resin joint. With progress of aging at 85°C in 85%R. H., the strength decreased rapidly in the early aging stage and decreased gradually by further aging. The strength of the Al/resin joint was inferior to that of the Cu/resin joint after aging. The fracture mainly occurred in the interface of the joint. The result of Fourier transform infrared spectroscopy analysis for the fracture surface showed that water absorption in the Al/resin joint occurs by aging and causes the degradation of the strength.

Abstract: The paper verifies anti-corrosion barrier protective properties of PE/PAK (polyethylene/polyacrylate), PE/PPE (polyethylene/polyproplylene) and PAD (polyamide) coatings of specific thickness on the surface of conventional ribbed bar B500B. Using pull-out test, the bond strength of such system was compared with bond strength of normal strength concrete (C30/37). Results of these tests show that key properties of coated systems are comparable to the previously tested epoxy coatings in case of their use in technical practice (protection of conventional rebar). In conclusion, their effective protective effect corresponds to minimal thickness higher than 300 μm but simultaneously lower the bond strength between the ribbed rebar and concrete. Keywords: corrosion of steel in concrete, organic coatings, bond strength, pull-out test, porosity

Abstract: The use of leaflet ribs from oil palm trees - Oil Palm Broom Fibres (OPBF) in reinforcingcement composites have shown some prospects according to recent studies. However, only little isunderstood regarding their bond interaction with cement matrices. Samples were prepared toinvestigate the pull-out response of OPBF in both single and combined form from concrete. For thecombined fibres, single OPBF strands were wound around one another longitudinally (in helical form)to form tendons. A comparison was made between the maximum bond strengths of untreated andtreated OPBF in concrete. The OPBF were pre-treated by soaking in sodium hydroxide andtriethylvinylsilane solutions to improve their bond strength with concrete. The reported treatmentscould improve the potential of OPBF tendons as reinforcement in lightly loaded concrete beamsultimately resulting in an environmentally friendly and affordable construction.

Abstract: In this work the properties of multilayer packaging materials based on PET/AlOx film with acrylic coating were studied. Multilayer packaging materials were produced on industrial laminators using three different adhesive compositions with different content of reactive groups. It is shown that the peculiarity of the chemical nature of adhesive components affects the bond strength and the seal strength of multilayer packaging materials.

Abstract: Information on deformation of coatings at different loading levels during peeling is given. It is shown that the deformations of the organosilicon coating appear already at the initial stages of loading, and the obtained data correlate with the data on acoustic emission. For a polyvinyl acetate coating at low loading levels, equal to 0.3-0.4 R, the release of acoustic signal energy is not observed. The absence of signals with a large amplitude at loading levels up to 0.7-0.8 R indicates the development of plastic deformations in the contact zone of the coating with the substrate. It was found that early localization of bond breaking in the contact zone, leading to the formation of a fracture focus, occurs in organosilicon coatings KO-168. For PVAC coatings, an abrupt growth of cracks is characteristic, which is preceded by its slow growth. The pseudoplastic mechanism of destruction of PVAC coatings has been established. The influence of the nature of the substrate on the change in the nature of the peeling of the coatings is considered.