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The Scientific World Journal
Volume 2014 (2014), Article ID 170187, 9 pages
http://dx.doi.org/10.1155/2014/170187
Research Article

Development of Hybrid Braided Composite Rods for Reinforcement and Health Monitoring of Structures

1Fibrous Materials Research Group (FMRG), School of Engineering, University of Minho, Azurem Campus, 4800-058 Guimaraes, Portugal
2Department of Civil Engineering, University of Minho, Azurem Campus, 4800-058 Guimaraes, Portugal

Received 21 October 2013; Accepted 4 December 2013; Published 20 January 2014

Academic Editors: D. G. Aggelis and H. K. Chai

Copyright © 2014 Sohel Rana et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In the present study, core-reinforced braided composite rods (BCRs) were developed and characterized for strain sensing capability. A mixture of carbon and glass fibre was used in the core, which was surrounded by a braided cover of polyester fibres. Three compositions of core with different carbon fibre/glass fibre weight ratios (23/77, 47/53, and 100/0) were studied to find out the optimum composition for both strain sensitivity and mechanical performance. The influence of carbon fibre positioning in BCR cross-section on the strain sensing behaviour was also investigated. Strain sensing property of BCRs was characterized by measuring the change in electrical resistance with flexural strain. It was observed that BCRs exhibited increase (positive response) or decrease (negative response) in electrical resistance depending on carbon fibre positioning. The BCR with lowest amount of carbon fibre was found to give the best strain sensitivity as well as the highest tensile strength and breaking extension. The developed BCRs showed reversible strain sensing behaviour under cyclic flexural loading with a maximum gauge factor of 23.4 at very low strain level (0.55%). Concrete beams reinforced with the optimum BCR (23/77) also exhibited strain sensing under cyclic flexural strain, although the piezoresistive behaviour in this case was irreversible.