Mechanical properties of concrete reinforced with recycled HDPE plastic fibres

This work investigates potential engineering benefits of the pioneering application of simply extruded recycled high-density polyethylene (HDPE) plastic fibres in structural concrete. Mechanical and serviceability properties of concrete are studied through the testing of seven series of specimens: one made of the plain concrete and, for each of the two fibre diameters Ø1=0.25mm and Ø2=0.40mm, three series with 0.40%, 0.75% and 1.25% volume fraction of fibres. While the compressive strength and the elastic modulus of concrete were unaffected, the tensile strength and flexural (rupture) modulus were marginally increased, between 3% and 14% in the presence of HDPE fibres. Fibres mainly contributed by providing the post-cracking flexural ductility and through improving serviceability properties of concrete such as the reduced plastic shrinkage cracking, drying shrinkage and water permeability. The durability of HDPE fibres was assessed by means of the scanning electron microscope (SEM) imaging that showed no signs of their chemical deterioration in concrete. All findings suggest that recycled HDPE fibres can be instrumental in creating a new value chain in construction industry while also positively contributing to its environmental performance.