Fatigue Behavior of Rubber Modified Pavements Author(s): Raad, Lufti andStephan Savounddjian Origin: Alaska Date: May, 1997 Categories: Performance Key Words: fatigue, Asphalt-Rubber, PlusRide, stiffness Summary: 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.