Recycling, Rubber

Abstract An overview of the uses for worn out scrap and reject rubber parts and articles, primarily tires, is presented. Uses and processing of worn out scrap and reject rubber include scrap rubber as a final source, pyrolysis of scrap rubber, depolymerization, rubber–asphalt modification, cryogenic pulverizing and mechanical tire shredding, rubber reclaiming, civil engineering, and tire retreading. Scrap rubber as a fuel source (burning rubber, sometimes known as tire‐derived fuel) in cement kilns, electric utilities, pulp and paper mills, and dedicated tire‐to‐energy plants is discussed. Processes for pyrolyzing rubber into oil and char are described, as are projects using rubber in asphalt and legislation being enacted to encourage the use of asphalt in rubber. Methods for cryogenically pulverizing and grinding tires are included. Methods of devulcanizing rubber using digesters, and heater or pan and reclaimator processes are presented. Uses of scrap rubber in civil engineering include erosion control retaining walls, fill material, and athletic and playing surfaces.