Early age performance and mechanical characteristics of recycled PET fibre reinforced concrete

In this study the performance of concrete reinforced with fibres produced from waste non-biodegradable plastic, polyethylene terephthalate (PET), has been thoroughly investigated. The novelty of the study, to the authors’ knowledge, consists in the fact that fibres have been employed as directly shredded from collected waste plastic bottles, with no processing through, e.g., plastic melting and fibre spinning. Moreover, a comprehensive investigation has been herein undertaken, which ranges from the identification of the mechanical behaviour of the fibres to the assessment of their bond with the matrix and of the early age and hardened state properties of the recycled PET fibre reinforced concrete. Different types of shredded recycled PET fibres, straight and deformed, together with different fibre lengths, 30 mm and 50 mm, have been assessed, for varying percentage addition in concrete. The tensile properties and pull out characteristics of the fibres have been determined. The effects of fibres in mitigating plastic and restrained drying shrinkage cracking were then assessed and, finally, the compressive strength and the flexural performance of the fibre concrete were determined. The cracking potential of fibre-reinforced mortar thin slabs was also assessed. The use of shredded recycled PET fibres in concrete has been shown to lead to interesting improvements in performance for various fibre concrete characteristics and offers a potential alternative for this material.