Babbitt, Minnesota: Case Study of Pretreated Crumb Rubber Modified Asphalt Concrete

Abstract

A 2.38-mm (No. 10) mesh crumb rubber from waste passenger tires was pretreated with a low-viscosity petroleum-based product and used as an aggregate replacement in asphalt concrete mixtures. The preconstruction testing consisted of the development of an appropriate aggregate gradation, mix design information, and fundamental mixture properties such as temperature susceptibility, moisture sensitivity, low temperature behavior, and permanent deformation characteristics. Five crumb rubber modified (CRM) asphalt concrete plus two control test sections were placed in Babbitt, Minnesota, in the fall of 1993. Variables in the CRM sections include pretreated and untreated crumb rubber and CRM mixtures in just the wear course or throughout the 150-mm (6-in.) pavement section. Laboratory results indicated that there was little difference in the temperature susceptibility between the mix design and behind-the-paver mixtures. Although the mix design samples indicated some increase in the moisture sensitivity of the C...