Treatment of Steel Surfaces for Effective Adhesive Bonding

Abstract

In the FRP strengthening of steel structures, cohesion failure in the adhesive is the preferred mode of debonding failure at FRP-to-steel interfaces so that the design theory can be established based on the properties of the adhesive. In this paper, results from a systematic experimental study are presented to examine the effects of steel surface treatment and adhesive properties on the adhesion strength between steel and adhesive. The test results show that adhesion failure can be avoided if the steel surface is grit-blasted prior to bonding and the treated surface can be characterised using three key surface parameters.

Strengthening of steel structures with fiber-reinforced polymer composites

“…As adhesion failure depends on the method and degree of surface treatment, especially to the steel substrate, which is difficult to control on site, the development of a design theory becomes much more involved. This important issue has not been given adequate attention in previous studies, but has been focused on in some recent research [17]. The authors thus strongly believe that in FRP-strengthened steel structures, interfacial failure should occur within the adhesive layer in the form of cohesion failure (Fig.…”

“…Among various mechanical abrasion approaches, grit blasting appears to be the most effective [15,20,31,32] and is recommended by some existing guidelines on the FRP strengthening of metallic structures [22,33]. Tests recently conducted by Teng et al [17] showed that with the four types of different adhesives used in their study, adhesion failure was avoided when the steel surface was grit-blasted prior to bonding. The grit used in grit blasting may be made of different materials and have different particle sizes.…”

“…The grit used in grit blasting may be made of different materials and have different particle sizes. Existing studies [17,20,34] have shown that grit blasting can modify the chemical composition of the surface by introducing grit residues to the surface, so it is important to choose a grit material which is chemically compatible with the adhesive. The particle size of grit may have a pronounced effect on surface energy and surface roughness, but the limited existing studies [17,20] have revealed that within the range of grit particle sizes examined in these studies (i.e.…”

“…The following methods are available for surface characterization: (a) a VCA (video contact angle) device can be employed to obtain contact angle measurements from which the surface energy can be evaluated; (b) an SEM/EDX (scanning electron microscopy/energy dispersive x-ray) system can be used to measure the surface chemical composition; and (c) a profilometer can be used to measure the surface roughness and topography [17]. By using these devices, Teng et al [17] showed that the characteristics of surfaces are consistent after being grit-blasted using the same grit, which suggest the possibility of developing a standard preparation process to ensure a good surface with a sufficient adhesion strength.…”

Fatigue tests on UHM-CFRP strengthened steel plates with central inclined cracks under different damage levels

“…The strengthened surface of the steel plates was sand-blasted first for better bonding with the CFRP laminate [38]. The abraded surface was then cleaned of contaminants using acetone solution.…”