Industry Reports

Report No.	IP23(jot this number down to order)
Title	Design Methods for Paving Mixtures Using Wet Process As Asphalt Rubber
Author(s)	Chehovits, James G.
Publisher	Crafco, Inc.
Pub. Date
Pages	28 pages
Keywords
Description	Asphalt rubber (AR) produced using the wet process in which the crumb rubber modifier (CRM) is pre-mixed and reacted with the hot asphalt cement can be used in a variety of paving mixtures and applications. These applications include 1) surface treatments, 2) open, gap, and dense-graded hot-mixed asphalt (HMA) and 3) crack and joint sealants. AR typically has significantly different physical characteristics than unmodified asphalt cements. These differences include 1) higher viscosity, 2) lesser temperature susceptibility, 3) increased aging resistance, and 4) increased elasticity. Appropriate use of AR in paving applications requires that the binder be designed and formulated for the specific application, and that the final mixture with aggregate be correctly designed. The differing physical properties of AR may require that normal mixture design procedures by modified to account for these differences in binder characteristics. High CRM contents can produce AR binders with physical properties that are modified to the extent that they may be sued in manners and applications not possible with unmodified asphalt cement. The objective of this paper is to present mixture design concepts and methods that can be used to design surface treatments, and HMA in open, gap, and dense-graded applications when using AR produced using the wet process.
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