Abstract
Strengthening by fiber-reinforced polymers (FRPs) is one of the most common solutions to the ageing infrastructures. However, long-term durability of such systems under different environmental conditions needs to be understood properly before widely adopting these methods in the field. This paper presents research outcomes from an experimental program carried out to determine the influence of moisture on the durability of the bond between FRP and concrete along with its constituent materials. Performance was evaluated through single lap shear bond tests and various kinds of tests on the resin samples, including water absorption, mechanical characterization, and glass transition temperature () analysis. The specimens were exposed to continuous water immersion and wet-dry cycles for a maximum period of up to 24 and 18 months, respectively. The results show some deterioration on the material and the bond properties in both exposure conditions. The bond strength decreased up to 32 and 12% for high-strength and normal-strength concrete substrates, respectively, after continuous immersion, indicating the key role of the substrate in the durability of bonds. As a result of exposure, failure propagated towards the primer-concrete interface region. The failure mode changed from concrete cohesion to primer-concrete mixed failure for normal-strength concrete and from mixed failure to complete adhesion failure in case of high-strength concrete. These shifts in failure patterns are mainly due to destruction of the adhesion bond caused by water molecules at the interface. However, it is found that the loss of the adhesion bond is somehow compensated by the good mechanical interlocking obtained by proper surface roughness condition of the substrate. Finally, the effects of water were also investigated in interfacial bond stress-slip laws and fracture energies.
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Acknowledgments
The authors would like to acknowledge contributions made by Mr. Atsuya Komori and Mr. Atushi Kitami for this research. The authors are also grateful to Nippon Steel and Materials Co., Ltd., for providing necessary epoxy resins and carbon fiber sheets for this study. This study was conducted with the financial aid provided by the Grant-in-Aid for Scientific Research (A) No. 22246058.
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Published In
Journal of Materials in Civil Engineering
Volume 27 • Issue 2 • February 2015
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Aug 31, 2013
Accepted: Mar 31, 2014
Published online: Jul 11, 2014
Discussion open until: Dec 11, 2014
Published in print: Feb 1, 2015
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