Jordan Journal of Civil Engineering, Volume 5, No. 2, 2011 - 210 - Assessment of the Extended Fatigue Life for Rubber and Polymer Modified Asphalt Mixtures Using Flexural Bending Beam Fatigue Test Mena I. Souliman 1) and Kamil Kaloush 2) 1) Graduate Research Associate, Department of Civil and Environmental Engineering, P.O. Box 875306, Tempe, AZ 85287-5306, Arizona State University, Arizona, USA. E-mail: Mena.Souliman@asu.edu 2) Associate Professor, Department of Civil and Environmental Engineering, P.O. Box 875306, Tempe, AZ 85287-5306, Arizona State University, Arizona, USA. ABSTRACT Load associated fatigue cracking is one of the major distress types occurring in flexible pavement systems. Flexural bending beam fatigue laboratory test has been used for several decades and is considered to be an integral part of the new superpave advanced characterization procedure. One of the most significant solutions to prolong the fatigue life for an asphaltic mixture is to utilize flexible materials as rubber or polymer fibers. A laboratory testing program was performed at Arizona State University (ASU) on a reference, Asphalt Rubber (AR) and polymer modified gap graded mixtures. Strain controlled fatigue tests were conducted according to American Association of State Highway and Transportation Officials (AASHTO) procedures. Using COANOVA statistical analysis approach, the results from the beam fatigue tests indicated that the AR and polymer modified gap graded mixtures would have much longer fatigue life compared with the reference (conventional) mixtures. KEYWORDS: Pavement design, Hot mix asphalt, Fatigue, Asphalt rubber, Polymer fibers. INTRODUCTION The flexural fatigue test is used to characterize the fatigue life of Hot Mix Asphalt (HMA) at intermediate pavement operating temperatures. This characterization is useful, since it provides estimates of HMA pavement layer fatigue life under repeated traffic loading. In a well designed pavement, strains in the pavement are low enough, so that fatigue is not a problem. However, when pavements are under-designed, strains are sufficiently high to cause fatigue failures under repeated loads. These failures ultimately result in fatigue cracking which will cause disintegration of the pavement if not maintained in time. A potential solution of this problem can be resolved by extending the fatigue life of HMA mixtures by introducing some additives that will make HMA more flexible. Several previous studies recommended using rubber and polymer fibers to improve the fatigue life of HMA. The basic flexural fatigue test subjects an HMA beam to repeated flexural bending in a controlled atmosphere. In order to relate laboratory results to normally observed field performance, a shift factor of 10 to 20 is typically needed. Because of the testing equipment complexity and long testing times, the flexural fatigue test is primarily a research test and is not a standard test in superpave mix design or quality assurance testing. The standard beam fatigue procedure is found in: AASHTO T 321: Determining the Fatigue Life of Compacted Hot-Mix Asphalt (HMA) Subjected to Accepted for Publication on 15/4/2011. © 2011 JUST. All Rights Reserved.