Effect of strain waveform modeling and loading frequency on the fatigue life of asphalt concrete

Abstract

The fatigue life of asphalt mixes in laboratory tests is commonly determined by applying a Sinusoidal or Haversine waveform with a specific frequency, while the pavement structure and loading conditions affect the shape and the frequency of tensile response pulses at the bottom of the asphalt layer. In this study, a Novel function is first evaluated to model the shape of the tensile strain waveform in longitudinal and transverse directions. The effect of strain waveform modeling using three waveforms of Haversine, Sinusoidal, and Novel on the fatigue life of asphalt mixes is then investigated through dynamic analysis of pavement and four-point bending beam fatigue test. All fatigue tests were continued to the third phase of fatigue life. Results showed a strong relationship between fatigue life based on the 50 % reduction of stiffness criteria and fatigue life based on energy methods under different loading waveforms and loading frequencies. It is also indicated that the loading waveform and frequency significantly affect the fatigue life of asphalt mixes. Much attention should be paid to determining these two parameters for a realistic simulation of the fatigue life of asphalt layers under the effect of moving loads. Furthermore, a new energy parameter is introduced to represent the fatigue life of asphalt mixes under a specific loading waveform at different loading frequencies. This energy parameter can be incorporated directly into pavement design.