Fatigue properties of crumb rubber asphalt mixtures used in railways

摘要

The use of asphalt mixtures in railway tracks provides a positive contribution to the bearing capacity, stability, durability and more importantly damping properties of the railway structure particularly for the new generation of low-vibration-railway track systems. However, one of the main concerns in the use of asphalt mixtures in railways is their fatigue cracking caused by the repeated traffic loading. The present study focused on the fatigue damage behavior of asphalt mixtures in the railways through using the viscoelastic continuum damage theory. Three experiments of creep compliance, constant crosshead rate and cyclic fatigue tests were carried out on some asphalt mixtures with different air void contents and aging conditions. Based on the results obtained, the crumb rubber modification of railways asphalt mixtures at low stress levels increases the fatigue life of asphalt up to 7.2 times while this increase is at the most 3.6 for the highway asphalt mixture. Furthermore, reducing the air void content from 4% to 2% for the crumb rubber modified asphalt mixture increases the fatigue life by 9.4 times at high stress levels and 18.2 times at low stress levels, which is a great improvement. It was shown that the lowest fatigue life is obtained in the aged crumb rubber modified mixture (i.e., 20 percent of unmodified asphalt mixture). (C) 2018 Elsevier Ltd. All rights reserved.