Sustainable rubber recycling from waste tyres by waterjet: A novel mechanistic and practical analysis

Abstract Production and disposal of car tyres are major contributors to environmental damage. The first stage in tyre rubber recycling is granulation to smaller particle sizes. The sub-optimal physical, mechanical and chemical properties of mechanically ground tyre rubber (GTR) when incorporated into recycled blends are major obstacles to wider use of this potentially sustainable, recovered resource. Consequently, newly manufactured tyres contain less than 5% recycled material. This study compares two types of GTR product: mechanically ground crumb (MGC) and ultrahigh pressure waterjet-produced rubber crumb (WJC). A novel image analysis method showed that when the two particle types were compared, MGC was associated with both greater convexity and sphericity: the geometric mean ratio of MGC/WJC sphericity was 1.67. When part-recycled rubber blends comprising 30% crumb of particle size