Modelling asphalt binder fatigue at multiple temperatures using complex modulus and the LAS test

Abstract

ABSTRACT The linear amplitude sweep (LAS) test is useful for evaluating the fatigue of asphalt binders. In this paper, the combined effects of strain and temperatures are investigated, and a method for estimating binder fatigue behaviour is introduced at different temperatures from limited measurements. LAS tests were conducted on several different PG-grade binders at four different temperatures. The results show that LAS parameters A and B at different temperatures maintain a linear relationship with the binder complex modulus (G*) measured at corresponding temperatures. Therefore, a fatigue life model, accounting for strain level and temperature, is proposed using a power function of the binder G*, which can account for temperature effects. To verify the model, its parameters are fitted using test data at two temperatures were used to predict the fatigue life at additional temperatures. This study findings offer a simpler and reliable method to predict the values of fatigue life at new temperatures using both 35% damage level and maximum stress failure criteria that are recommended in AASHTO TP101-12 and AASHTO TP101-14, respectively. The new prediction method will allow a wider use of the LAS procedure regarding the effects of temperature and strain level for which binders are subjected to the pavement.