Environmental benefits of using ground tyre rubber in new pneumatic formulations: A life cycle assessment approach

Abstract

Life cycle assessment methodology was applied as a tool to evaluate the real environmental benefit of using recycled waste tyres in mixture with virgin rubber. Styrene–isoprene–styrene rubber was mixed with different amounts of ground tyre rubber and vulcanised. Thermomechanical analysis (i.e. differential scanning calorimetry and thermogravimetric analysis) and dynamic mechanical thermal analysis were carried out in order to evaluate the compatibility of the rubber mixture and the chemical–physical properties of the vulcanised products. Experimental analysis results show that the addition of ground tyre rubber up to 50 phr does not sensibly affect the vulcanisation reaction, the wet skid resistance and the rolling resistance. Life cycle assessment results show that the main environmental impacts of the ground tyre rubber are associated to the use of virgin rubber (47.1%) and carbon black (34.3%) while the tyre grinding process contributes only for 4%. Because ground tyre rubber contains carbon black in its formulation, the substitution of virgin rubber with ground tyre rubber has double environmental benefits: to reduce the need of both amounts of virgin rubber and fresh carbon black in the new formulation.