Development of Crumb Rubber Modified Binder Asphalts in WA

Every year millions of tyres in Australia reach their functional end-of-life. These end-of-life tyres contain petroleum derivatives and significant embedded energy and are therefore a potentially valuable resource for recycling. At present, most end up in landfill, inappropriately dumped or exported overseas. Rubber and carbon black make up approximately 70% of the weight of a tyre. One potentially high value alternative destination for these materials is as a crumb rubber modifier (CRM) in bitumen used for road construction. The use of CRM binder in both asphalt and sprayed bituminous seals can provide increased durability and cracking resistance. In addition to improved performance, recycling ground tyre rubber reduces landfill volumes and preserves natural resources. This presentation will detail the findings of two recent WARRIP projects, exploring the development of a crumb rubber modified (CRM) binder incorporating 18% crumb rubber as well as the use of the binder in both Open Graded Asphalt (OGA) and Gap Graded Asphalt (GGA). The CRM OGA has proven to be a practical replacement for OGA with PMB, has increased binder content and allows for increased air voids. The CRM GGA mixes have a binder content of about 8% and have improved fatigue characteristics over standard mixes, particularly at lower strain levels.

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