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Keywords:

  • aging;
  • asphalt modification;
  • extender;
  • filler;
  • ion exchanger;
  • natural rubber;
  • reclaims;
  • reclamation;
  • recycling;
  • rubber powder;
  • rubber vulcanizate;
  • scrape tires;
  • surface modification

Abstract

Summary: The scrape rubber is difficult to recycle, since it is not thermoplastic material. Consequently, it must be converted into a powder. The scrape rubber powder can be reused via different ways: a- Reclamation The reclamation process was studied. This process converts the rubber powder into elastic-plastic materials. The obtained reclaims were introduced into NR formulations. The obtained data reveal that, 10–30% reclaimed rubber can replace virgin NR without scarifying the basic properties of the rubber vulcanizates. In such way we can gain cost reduction. b- Reuse as filler-extender The rubber powder was treated with some oxidizing agents and namely HNO3 and H2O2 to modify its surface. The result of such treatment creates some functional groups such as carbonyl groups. The treated rubber powder was used as filler-extender in NR formulations. The treated rubber powder improves the tensile strength of the vulcanizates to some extent (62%). On the other hand, the treated powder was used in combinations with the classical reinforcing carbon black (HAF). The obtained results showed that, 20–40% of HAF can be replaced by the treated powder in NR mixes. The obtained vulcanizates have good physico-mechanical properties. In such way the production cost can be reduced. c- Utilization of sulfonated rubber powder as ion exchanger The rubber powder was sulfonated with Sulfuric and chlorosulfonic acids. The sulfonated product was evaluated as ion exchange resin to clear the industrial wastewater from heavy metals. The data showed that the Sodium salt form is more efficient ion exchanger than the acid form. d- Utilization in pavement The rubber powder is mixed with asphalt used in road pavement. The performance of asphalt concrete greatly depends on the particle size of the rubber powder used. The fine powder greatly improves the mechanical performance of the road pavement. The rubber powder was chemically modified. It was found that such modification had greatly improved the performance road pavement.