Asphalt Rubber Technology Information Center
Evaluation of CalTrans Modified Binder (MB) Specification: Final Report
Hicks, R.G and Epps, Jon  
California, Industry  
March, 1999  
Key Words:

Caltrans has developed a modified binder (MB) specification for asphalt rubber binders.  The initial specification was
developed through a laboratory and field pavement performance study which included an evaluation of six field projects
initially and reportedly validated on a number of additional field projects.  Questions raised by industry regarding this
specification include the following: (1) does the cup and plate test used by Caltrans quantify the asphalt rubber binder (2)
is the cup and plate test repeatable within and between laboratories? (3) Are the failure criteria developed appropriate
for asphalt rubber? (4) Were the lab and field data used to develop the failure criteria sufficient and has the failure criteria
been adequately validated? (5) Were factors such as pavement geometry, mix design, existing pavement condition,
materials, and construction practices considered in the development of the specification?
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