Compressive and flexural behaviour and theoretical analysis of flax fibre reinforced polymer tube encased coir fibre reinforced concrete composite

Published Date
December 2013, Vol.52:801–811, doi:10.1016/j.matdes.2013.06.018

Author 

Libo Yan ^,

Nawawi Chouw

• Department of Civil and Environmental Engineering, The University of Auckland, Auckland Mail Centre, Private Bag 92019, Auckland 1142, New Zealand

Received 10 April 2013. Accepted 8 June 2013. Available online 19 June 2013.

Highlights

• •
  Slippage between FFRP tube and concrete core is eliminated.
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  An energy ductility index is developed to define ductility of FFRP-CFRC.
• •
  Cracking strength and moment of FFRP-CFRC beam is larger than conventional RC beam.
• •
  Simplified analytical method is developed to predict resisting moment capacity.

Abstract

The use of cost-effective natural fibres, i.e. flax in fibre reinforced polymer composites and coir in concrete as building materials is a step to achieve a sustainable construction. Both flax fibre reinforced polymer tube encased-plain concrete and the tube encased-coir fibre reinforced concrete composites have potential to be axial and flexural structural members. However, in flexure, slippage between tube and the concrete core may compromise the performance of the composites. In this study, thin flax fibre reinforced polymer band rings were embedded into the tube inner surface in order to eliminate the slippage because a better tube and concrete interlocking was achieved. Therefore, one purpose of this study is to investigate the effect of band rings on the compressive and flexural properties of flax fibre reinforced polymer tube encased-plain concrete and the tube encased-coir fibre reinforced concrete. The ductility of these composites was evaluated using an energy ductility index based on measurement of fracture energy. Next, the cracking strength and neutral axis depth of the composite beams without band rings under flexure were analysed. Finally, based on linear elastic analysis, a simplified analytical method was developed to predict the resisting moment capacities of these composite beams. The test results indicate that in axial compression, the use of band rings reduced the ultimate compressive strength and ductility of both composites. In flexure, the band rings eliminated the slippage but increase the load carrying capacity and deflection. The predicted ultimate moment capacities of these composite beams match the experimental results well.

Keywords

• Flax fibre reinforced polymer
• Coir fibre reinforced concrete
• Confinement
• Ductility
• Slippage

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  Corresponding author. Tel.: +64 9 373 7599x84521; fax: +64 9 373 7462.

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