Collaboration between JCU and Fibercon wins The Australian Innovation Challenge (2015)

Recycled Plastic Fibre Reinforced Concrete

Team: Mr Shi Yin (JCU), Dr Rabin Tuladhar (JCU), Mr Tony Collister (Fibercon) and Mr Mark Combe (Fibercon)

(In picture: Mr Tony Collister, Mr Shi Yin, Mr Clive Mathieson - Editor the Australian, Dr Rabin Tuladhar)

Our translational research conducted in collaboration between James Cook University, Townsville and Queensland based fibre company, Fibercon wins the prestigious Australian Innovation challenge (2015) in the Manufacturing, Construction and Innovation category. Our innovation is the development of recycled polypropylene fibres from industrial plastic wastes to reinforce concrete in footpaths and precast elements. The Innovation Award is presented by The Australian in association with Shell and supported by the Department of Industry, Innovation and Science in association with The Australian and Shell.

Traditionally, steel mesh is used in concrete footpaths to control shrinkage cracks and enhance its robustness. As an alternative to steel mesh, various fibres such as steel, natural and synthetic fibres are also used in concrete to improve its post-cracking performance.  The most commonly used synthetic fibres in concrete are produced from virgin plastics. Recently, researchers have focused on the potential use of recycled plastic fibres in concrete. However, most of the research is focused in recycling polyethylene terephthalate (PET) plastics and is limited to laboratory tests with extremely low production rate. Furthermore, PET plastics are found to degrade when embedded in a highly alkaline concrete matrix, making its use impractical.

Our research has produced recycled polypropylene (PP) fibres from industrial plastic wastes such as offcuts and off-specification items. Using industrial plastic waste ensures constant source of recycled plastic with reliable quality control. Our production process includes melt-spinning and hot-drawing process where recycled polypropylene plastic waste is first melted into granules, then extruded and hot drawn. Diamond shaped surface indents are then placed on the fibre surface to improve its bonding with the concrete matrix. The fibres are subsequently cut into approximate length of 50mm.This process of producing recycled plastic fibres is suitable for large-scale commercial production. The extrusion and hot drawing process highly orients the polypropylene molecular chains, significantly improving its crystallinity, and hence improving the tensile strength and Young’s modulus of the fibres. Our tests have proved that the fibres bridge cracks in concrete effectively reducing crack-width and propagation of cracks. This enhances crack resistance, robustness and durability of concrete footpaths. Furthermore, recycled polypropylene fibres have excellent alkali-resistance making it suitable for long lasting concrete footpaths.

Our comprehensive life cycle assessment study, conducted in accordance with ISO14040, has shown that production of recycled plastic fibre produces 90% less CO and eutrophication (contamination of water bodies with nutrients) compared to steel required to achieve equivalent reinforcement. The use of recycled plastic fibres in concrete also reduces plastic wastes going into landfills and contributing towards sustainable development.

Our recycled plastic fibres have successfully been used to construct a 100m long concrete footpath at James Cook University (JCU), Townsville in May 2015. With the success in this trial footpath, recycled plastic fibre has now been specified to be used in all the footpath and landscaping in the upcoming Science Place Building at JCU. We are also working closely with other concrete companies to assess the potential use of recycled plastic fibres in concrete drainage pits and other precast concrete applications.

As Australia and Queensland is moving towards prioritizing translational research, this comes as a great example of a meaningful collaboration between the industry and the university which has successfully translated research outcomes into the mainstream concrete industry.

More details in our papers published in following international journals: Papers:

a) Post-cracking performance of recycled polypropylene fibre in concrete, Construction and Building Materials (2015): https://goo.gl/jKgDMg

b) A life cycle assessment of recycled polypropylene fibre in concrete footpaths, Journal of Cleaner Production (2015): https://goo.gl/OjL4Oj

c) Fiber preparation and mechanical properties of recycled polypropylene for reinforcing concrete, Journal of Applied Polymer Science (2015): https://goo.gl/aJCeHL

d) Use of macro plastic fibres in concrete: A review, Construction and Building Materials (2015): https://goo.gl/2PWtdn

e) Mechanical reprocessing of polyolefin waste: A review, Polymer Engineering and Science (2015): https://goo.gl/IYgRtk