Asphalt-Rubber An Anchor to Crumb Rubber Markets Third Joint UNCTAD/IRSG Workshop on Rubber and the Environment International Rubber Forum Veracruz, Mexico

2 Executive Summary The purpose of this paper is to familiarize the reader with the paving material asphalt-rubber (A-R) by providing historical perspective on its development and obstacles to its development. A-R has been a constant and stable market for crumb rubber producers in the United States most significantly within the vicinity of Arizona, California, and Florida. Agencies use A-R because of the engineering benefits it provides but also find that it contributes to the reduction of waste tires. Additionally, an overview of tire program management in the key states of Arizona, California and Florida will be included. Government tire programs have been required to control the flow and disposal of waste tires. A fee structure has been required to remediate waste tire piles and to add value to waste tires for processors. Fees have been used to provide equipment to processors and to stimulate the production of beneficial end uses of tires. As markets develop and piles are eliminated, fees can be reduced. Regulations that focus on only one beneficial end use are typically not successful. All environmentally economical options should be included. Stable crumb rubber markets encourage the development of new technologies that utilize the material. One emerging technology is a spray application to existing highway sound barriers that is crumb rubber based. Crumb rubber has a notable sound energy absorbing characteristic and is relatively inexpensive. This sprayed material is applied in thin layers approximately one quarter of an inch in thickness. The bonding materials experimented with to date have been synthetic stucco mud with crumb as the aggregate and a paint like polymer liquid. Asphalt-Rubber is not the solution to the waste tire problem, but when utilized by agencies that prefer its beneficial engineering characteristics such as durability, flexibility, strength, and resistance to cracking, it contributes significantly to the reduction of waste tires.