Development, characterisation and Finite Element modelling of novel waste carpet composites for structural applications

Carpets are composite materials and, like many composite materials, waste carpet is both difficult and expensive to recycle because of the complicated, multi-stage processes involved. Consequently, in the United Kingdom, approximately 400,000 tonnes of carpet waste are sent to landfill annually. However, the landfill option is becoming uneconomic due to increasing landfill charges, the reduction in landfill sites and changes in environmental legislation. This dual economic and environmental burden has led to research interest in the processing of waste carpets into useful feedstocks for use in manufacturing. This study describes the experimental characterisation of a novel structural composite material that has been fabricated from waste carpets, and which is intended for use in low grade structural applications such as agricultural fencing. Details of the manufacturing process for the composites are described, as are the results of tensile and three-point bending tests, and the observed failure modes post-testing. In addition, Finite Element (FE) analysis was used to simulate the structural behaviour of fencing posts and rails manufactured from the carpet-based composite, and these results are compared with commercially available timber and PVC equivalent designs. Finally, structural analysis and design optimisation of the composite fencing was undertaken and this is used to demonstrate that from a mechanical property standpoint, the novel waste carpet structural composite may offer potential as an alternative to the timber and PVC materials typically used in such applications. Therefore, this study has demonstrated a practical approach for recycling carpet waste, which could lead to a substantial reduction in the volume of carpet waste discarded to landfill and subsequently yield both economic and environmental benefits.