Physical and mechanical behaviour of a fibre-reinforced rubber membrane with self-healing purposes via microwave heating

Recycled rubber powder from shredded End of Life Tyres (ELTs) has been used for the development of a new elastomeric membrane with self-healing purposes via microwave heating. Nevertheless, due to the environmental exposure of this rubber-based material, the environmental conditions may contribute to premature deterioration of membranes, reducing their mechanical strength and durability over time. To improve it, steel wool fibres can be incorporated in the rubber-based matrix. Metallic fibres in composite materials are known for enhancing its strength and fatigue characteristics while increasing ductility. These fibres can also be used for self-healing purposes via heating process. Hence, the addition of fibres may influence the properties of the new membrane, although it is not clear how this influence works. For these reasons, fibres distribution and mechanical behaviour of fibre-reinforced rubber membrane under the influence of different environmental conditions have been studied. With these purposes, four different membranes, with the same rubber powder gradation, but with four different percentages of steel wool fibres, have been considered. In addition, the influence of fibres on preconditioned test samples under three different environmental conditions: water-saturated, cold and ageing, have been evaluated via tensile strength test. Finally, fibre distribution results showed that steel wool fibres presented a good distribution into the rubber-based membrane. However, due to the mixing process long fibres used may produce clusters in the central area of membranes, while short fibres disperse very well in the contour of the membrane. Additionally, it was found that steel wool fibres do not significantly contribute to improve the tensile mechanical properties of the membranes evaluated under different environmental conditions.