Crumb Rubber Modifier
Section 1038(d)of the Intermodal Surface Transportation Efficiency Act (ISTEA) mandated the States use of quantities of asphalt pavement containing recycled rubber. Section 205(b)of the NHS Designation Act of 1995 amended Section 1038 by striking subsection (d) eliminating the crumb rubber mandate and all associated penalties.
In Section 327 of the NHS Designation Act of 1995, Section 1038 of ISTEA was further amended to require research and development of tests and specifications for use of crumb rubber modified (CRM) asphalt in conformance with the Superpave performance-based specifications.
FHWA continues to encourage the use of waste tire rubber in engineering applications, including asphalt paving, where it is both cost effective and it can be properly engineered. States are not required to use crumb rubber in asphalt paving, but, when requested, FHWA provides technical assistance and will continue to provide technology transfer.
Under an interagency agreement the National.Institute for Occupational Safety and Health (NIOSH) with FHWA funding evaluated possible exposure and health effects of crumb rubber modified asphalt mixtues. NIOSH's overall assessment was made using data from seven projects. A composite report of the overall findings and conclusions is available on the NIOSH website http://www.cdc.gov/niosh/hhe/reports/pdfs/2001-0536-2864.pdf (.pdf, 0.6 mb). This report addresses issues of sampling methods, worker exposures, and health effects associated with conventional versus CRM asphalt paving
FHWA also coordinated its CRM efforts with the NCHRP 9-10 research project entitled Superpave Protocols for Modified Binders. The project was completed in February 2001 and the final report was published in August 2001 as NCHRP Report 459.
FHWA continues to support crumb rubber activities as one of the contributors to the Resource Conservation Challenge (RCC) Scrap Tire Action Plans.
In 2014, FHWA produced a Technical Brief on the "Use of Recycled Tire Rubber to Modify Asphalt Binders and Mixtures" available at ; https://www.fhwa.dot.gov/pavement/pub_details.cfm?id=930.
Additional information on crumb rubber is available from other organizations such as: