Scrap Tires | Scrap Tire News | Archived Article

LA County Broadens Asphalt Rubber Use

Los Angeles County, California has laid over 1 million tons of asphalt rubber since 1992, according to Frank Lancaster materials engineer for LA County.

Lancaster estimates the county has saved "millions of dollars" over that time because the asphalt rubber is laid at only half the thickness of regular asphalt. What's more, there've been no failures to date even in places where the rubberized pavements have been down for more than 10 years, Lancaster said.

While the majority of these pavements were laid using the popular and industry-predominant "wet" process in which crumb rubber is added to asphalt cement prior to incorporating the binder, the county has also been evaluating the "dry" method for the past several years. In the "dry" process crumb rubber is added directly to hot mix asphalt in the mixing process.

"We can't see any difference between it and the wet process," Lancaster said. Based on these evaluations, the county is planning several projects this year using the dry process, Lancaster said.

In addition, the county is evaluating the newer "terminal blend" process developed and patented by Texas-based Wright Industries. For terminal blend asphalt rubber, the rubber is blended into the asphalt at the refinery. In practice, the asphalt rubber is then shipped directly to the asphalt plant, just like regular asphalt or other raw materials used in pavement mixes. Highway departments or contractors then buy the asphalt rubber pre-mixed.

With the addition of these technologies, LA County becomes one of the first in the country to offer different options for asphalt rubber pavements.

back to archives