Abstract

States and contractors are investigating materials like ground tire rubber (GTR) as a substitute for polymer modification in asphalt binders. The Missouri Department of Transportation recently built two test sections at the National Center for Asphalt Technology (NCAT) Pavement Test Track in 2009 to validate this concept. The Test Track sections were monitored over six years for field performance such as rutting, smoothness, texture and cracking. Additionally, each mixture was sampled for laboratory characterization in terms of stiffness, rutting, cracking, and moisture susceptibility using standard laboratory procedures. Based on the gathered data, GTR mixtures can be used as an adequate polymer substitute without sacrificing asphalt mixture performance. The GTR mixture which was placed in 2009 has almost completed 20 million equivalent single axle loads without cracking or rutting.

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