Over 40 year ago, Charlie McDonald, an engineer for the City of Phoenix, developed ad time/temperature formula for
mixing scrap tire material and asphalt to develop a material that would make the asphalt behave much like tire rubber.
motivation started earlier when he was with the Bureau of Highways (now FHWA) and traveled extensively in State Parks in
California, living in a small trailer with a leaky roof and he
needed a flexible material to patch and seal the roof so the rather
primitive roadways would not continue to cause cracking.
After he joined the City of Phoenix, he continued his experiments, first in his kitchen and later in the engineering laboratory.
was satisfied he
had achieved the right formula, he
took the material to the street s where he
Application methods were primitive, but the binder he
created started a whole new paving industry.