Asphalt Rubber Technology Information Center
Fatigue Behavior of Rubber Modified Pavements
Raad, Lufti andStephan Savounddjian  
May, 1997  
Key Words:
fatigue, Asphalt-Rubber, PlusRide, stiffness  
Over the last 15 years, a number of rubberized pavement projects have been built in Alaska.  Initial laboratory and field
investigations sponsored by the Alaska Department of Transportation and Public Facilities (AKDOT & PF) and conducted
by Raad er al.  (1995) indicated improved fatigue performance of the rubberized sections in comparison with
conventional asphalt concrete pavements.  This report presents the results of a follow-up investigation to develop
design equations for rubberized pavements in Alaska.
Laboratory studies were conducted on field specimens using the flexural fatigue test in controlled-displacement mode.  
Specifically, the rubberized mixes included 1) Asphalt-Rubber concrete with AC-2.5 (wet process) and 2) PlusRide
RUMAC with AC-5.  Tests were performed for a range of temperatures varying between 22°C and -29°C.  Fatigue
relationships were developed in terms of repeated flexure strain, dynamic flexure stiffness of the mix, and repetitions to
failure.  In addition, relationships for the dynamic flexure stiffness as a function of temperature were also developed.  
The proposed fatigue equations were used ot compare the behavior of the rubberized mixes with conventional AC-5
mixes at 20°C Asphalt-Rubber and AC-5 mixes exhibit essentially similar fatigue resistance, whereas PlusRide as the
least fatigue life.  However, at 0°C, the fatigue resistance of PlusRide and Asphalt-Rubber exceed that of the
conventional AC-5 mix.  The fatigue equations were also used to compare the fatigue life of conventional and rubberized
pavements for different surface layer temperatures and foundation support conditions.
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