Better Roads

RoadScience by Tom Kuennen, Contributing Editor 6 September 2014 Better Roads A fter years of promotion, pavements using asphalt rubber, or rubberized asphalt (there's a difference), are spreading far and wide in the United States. Formerly a Southwest and California phenomenon – its use is mandated by California law – and a handful of states elsewhere, asphalt pavements containing rubber currently are being used in a majority of states. And while all those states may not have actual specifi cations for pavements containing rubber, they at least are giving them a try. Use of rubber in asphalt pavements likely will get a boost as the Federal Highway Administration (FHWA) updates its 1992 State of the Practice: Design and Construction of Asphalt Paving Materials with Crumb Rubber Modifi er (Search for FHWA-SA-92-022 in Google). In May 2013, representatives from the Rubber Manufactur- ers Association, Tire Industry Association, Rubber Pavements Association, Rubberized Asphalt Foundation, National Asphalt Pavement Association and Liberty Tire Recycling met with FHWA's John Baxter, associate administrator for infrastructure. Their purpose was to encourage FHWA to update that doc- ument to refl ect innovations and changes that have occurred in the rubberized asphalt industry since it was published 22 years ago. A new guide will be produced that will capture the best practices in design, construction, application, testing, storage and handling of rubberized asphalt materials in use today. The guide will help agencies and contractors that are explor- ing the implementation of rubberized asphalt technologies of various kinds by providing specifi cations and quality control procedures that have been successfully used around the globe. Asphalt containing rubber continues to stretch its way into more state Departments of Transportation. Rubber Expands Photo courtesy of Tom Kuennen Thin overlay of warm-mix asphalt contain- ing terminal blend asphalt rubber and Evotherm warm mix additive is placed on Calif. 1, the Pacifi c Coast Highway, near Fort Bragg two hours after loadout.

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• ROAD SCIENCE: Rubber Expands: After years of promotion, pavements using asphalts rubber, or rubberized asphalt (there's a difference), are spreading far and wide in United States
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