Rubber Modified Asphalt Binders

History of Crumb Rubber

The history of adding recycled tire rubber to asphalt paving material can be traced back to the 1940's when U.S. Rubber Reclaiming Company began marketing a devulcanized recycled rubber product, called Ramflex (tm), as a dry particle additive to asphalt paving mixtures. 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 a 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 Producers Group in the mid-1980's. Ramflex (tm) disappeared from the market when U.S. Rubber Reclaiming Company was sold by its parent corporation.

The other half of the history originates in Sweden. In the 1960's, two Swedish companies began developing an asphalt paving surface mixture that would resist studded tire and chain wear. The mixture incleded a small amount of crumb rubber as an aggregate and was called by the trade name Rubit (tm). In the late 1970's, this product was introduced and patented in the United States as PlusRide (tm) by All Seasons Surfacing Corporation. The design of PlusRide (tm) evolved through 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.

With the environmental interest to find alternative uses for scrap tires and the enactment of ISTEA in 1991, asphalt technologists and rubber-recycling entrepreneurs began looking to modify or improve on the existing technologies available to add crumb rubber to asphalt paving materials. Several new technologies have emerged and are being evaluated. The initial field test sections of crumb rubber asphalt mixtures imilar to PlusRide (tm) and McDonald technology were laid in 1989 and 1990, respectively. Additional technologies have been introduced since that time, but have not been widely evaluated.