Bond Characteristics and Qualifications of Adhesives for Marine Applications and Steel Pipe Repair

Abstract

Performance of adhesives significantly affects the overall behavior of structural elements, especially in the process of developing innovative designs using new materials. Adhesives that bond metals, plastics, FRP and other materials have been used in transportation, industrial and marine applications. Fundamental understanding of the bond behavior and load transfer mechanisms of different adhesives is essential prior to their use in civil infrastructure applications.

This thesis presents the results of an extensive research program conducted to determine the engineering properties of different structural adhesives under normal and severe environmental conditions. The bond characteristics between composite-to-composite and composite-to-steel materials are investigated. The performances of two different structural adhesives are evaluated by testing 105 single-lap shear specimens. The research includes the effect of severe environmental conditions using the classical direct lap-shear tests. The factor considered is time-to-failure in which the specimens are submerged in de-ionized water with different pH values and subjected to different temperatures at different stresses. The program includes also examining the cleavage peel and short term creep properties. Adhesive behaviors, as well as the failure modes for each adhesive, are presented. The influence of preparation procedures of the substrate on the shear strength of the adhesives is also studied.

Test results show a significant impact of the pH level and temperature on the shear strength and bond characteristics of the two structural adhesives considered in this investigation. Test results were used to determine the most appropriate adhesive for marine application and repair of steel pipeline.