Composites and FRP-Strengthened Beams Subjected to Dry/Wet and Salt Fog Cycles
Publication: Journal of Materials in Civil Engineering
Volume 26, Issue 12
Abstract
Carbon (CFRP) and glass (GFRP) fiber-reinforced composites of epoxy matrix are considered in the study, with greater emphasis on GFRP. Accelerated conditioning was imposed in the form of salt fog cycles, hygrothermal cycles (tap water), and tidal-like cycles (aqueous solution of NaCl, ), both on laminate composites and on beams externally reinforced with fiber-reinforced polymers (FRP) on their soffit. Freeze/thaw cycles were also applied to the study of degradation of the laminates. Mechanical tests showed degradation due to damage to the matrices, fiber-matrix linkage or bond between FRP and concrete. Several advanced techniques were used to interpret the results and enable better understanding of the phenomenological data. Changes on the glass transition temperature () of the epoxy matrix are reported as possible indicators of decrease of the tensile strength of the GFRP composite. Attention is given to the evolution of the relative values of the tensile strength of concrete and adhesive along time given their importance on the effectiveness of the FRP-adhesive-concrete joints. The results revealed, e.g., that the more severe decrease of the carrying capacity of the beams was due to the salt fog cycles in the beams strengthened with CFRP.
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Acknowledgments
Research was financed by Fundação para a Ciência e Tecnologia (FCT) under Project DUST-PTDC/ ECM/100538/2008, and the authors thank that support. Members of Strategic Projects of UNIC and CENIMAT, sponsored by FCT participated in the research and Dr. J. Canejo of CENIMAT helped with obtaining SEM data.
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Information & Authors
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Published In
Journal of Materials in Civil Engineering
Volume 26 • Issue 12 • December 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Feb 18, 2013
Accepted: Dec 16, 2013
Published ahead of production: Dec 18, 2013
Published online: Jun 20, 2014
Discussion open until: Nov 20, 2014
Published in print: Dec 1, 2014
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