Asphalt Rubber Brief Introduction
By ASTM definition, asphalt rubber is “A blend of asphalt binder, reclaimed tire rubber, and certain additives in which the rubber component is at least 15 percent by weight of the total blend and has reacted in the hot asphalt binder sufficiently to cause swelling of the rubber particles.” It can be used for chip seals and interlayers, as well as hot mix asphalt paving mixtures.
In the late 1930s, asphalt rubber materials were began to be used as joint sealers, patches and membranes.
In the early 1950s, a study intending to evaluate “The Effect of Various Rubbers on the Properties of Petroleum Asphalts.” was conducted by Lewis and Welborn of the Bureau of Public Roads (BPR) of the State of Calinifornia, using a number of different rubber powders and asphalt combinations. The October 1954 issue of Public Roads published the results of the study, along with results of a companion “Laboratory Study of Rubber-Asphalt Paving Mixtures,”conducted by Rex and Peck at BPR, which examined a wide range of rubber materials using both wet and dry methods of adding them to hot mix asphalt.
In March 1960, the first symposium on rubber in asphalt was held by the Asphalt Institute in Chicago, II.
It was in the mid 1960’s that Charles H. MacDonald developed the “wet process” (also called the McDonald process) for producing asphalt rubber. In about 1959 when working with the U.S. Bureau of Public Roads(now FHWA, the Federal Highway Administration) which he served for years, McDonald found an elastomeric material to coat his roof of trailer which often cracked and this solved his problem. In the early 1960’s McDonald retired from the BPR and became an engineer for the City of Phoenix, Arizona. While devising methods to repair potholes on the streets of Phoenix, he experimented with adding ground tire rubber to hot liquid asphalt and created the new material which he called asphalt-rubber and used to create “band-aids” for pothole repair. The binder system was spray applied and the patch was a “localized chip seal”placed by hand over a limited pavement area.
In 1967 the first “large area” spray application occured which produced poor results because of the high viscosity.
In the 1970s, successful “large area” spray applications were placed in Arizona. These chip seal coat applications using asphalt-rubber binders became known as stress-absorbing membranes (SAM).
In 1972, the first SAMI is placed by the Arizona DOT. SAMI, stress-absorbing membrane interlayers in full name, is asphalt rubber chips seals overlaid with hot-mix asphalt.
By 1975, crumb rubber was successfully incorporated into hot mix asphalt in Arizona.
Starting in about 1985 AR binder usage was expanded by adding AR to hot mixes including gap graded and open graded mixes.
Now asphalt rubber are widely used in US, Canada, Europe, South Africa and Asia. We provide crumb rubber production lines for you to make profit in the attractive industry.