The history of adding recycled tire rubber to asphalt paving material can be traced back to the 1940's when the U.S. Rubber Reclaiming Company began marketing a devulcanized recycled rubber product, called Ramflex (TM), as a dry particle additive to asphalt paving mixture. In the mid-1960's, Charles McDonald began developing a modified asphalt binder using crumb rubber. This product was marketed by Sahuaro Petroleum and Asphalt Company as Overflex (TM).

The Arizona Refining Company Inc., created second modified binder in the mid-1970's, replacing a portion of the crumb rubber with devulcanized recycled rubber and marketing it under the name Arm-R-Shield (TM). Both Overflex (TM) and Arm-R-shield (TM) were patented and eventually brought under single ownership. The companies marketing these two products founded a trade association known as the Asphalt Rubber Producer Group in the mid-1980's. Ramflex (TM) disappeared from the market when its parent corporation sold the U.S. Rubber Reclaiming Company.

In addition to the US, Sweden also made tremendous contributions to the development of rubberized asphalt. In the 1960's, two Swedish companies began developing an asphalt paving surface mixture that would resist studded tire and chain wear. The mixture included a small amount of crumb rubber as an aggregate and was named Rubit (TM) In the late 1970's this product was introduced and patented in the United State as PlusRiden (TM). It evolved in a series of field projects in Alaska and other states from 1979 through 1985. PlusRide (TM) has been managed by a number of firms and is presently marketed by Envirotire, Inc.

In recent years there has been a great surge to make use of the waste tires that are being stockpiled all around the world. This surge is primarily due to the advancement in technology and realization of benefits associated with application of used tires. Because of the increase in the number of tires accumulating around the world, and environmental hazards associated with them, more nations are looking for ways to make use of this tremendous resource.

Table of Contents | Executive Summary | Introduction | History of Noise Reducing Pavement | The Process of Producing Rubberized Asphalt | Current Uses of Rubberized Asphalt | Tables | Studies of Rubberized Asphalt Outside of Sacramento County | Sacramento County Rubberized Asphalt Noise Studies | Conclusions of the Studies Conducted in Sacramento County | Appendix A - Acoustical Terminology | Appendix B - Noise Standards Commonly Applied to Projects in Sacramento County