Abstract
An accurate assessment of the fatigue life of hot mix asphalt (HMA) mixtures depends on the criteria used in the fatigue analysis. In the past, various studies have been conducted on crack initiation and crack propagation of the HMA mixtures. Most of these studies were focused on the beam samples with or without a sawed crack at the bottom. This paper presents and discusses two different fatigue life criteria for two-dimensional problems represented by cylindrical samples. One criterion is based on the rate of accumulation of the tensile horizontal plastic deformation (HPD) as a function of the number of load repetitions. The second criterion is based on fracture mechanics, stress intensity factor, and the rate of crack growth with respect to the number of load repetitions. It was found that, because of three-dimensional nature of the crack growth in cylindrical samples, the Paris' law was violated. It is shown that the rate of crack growth criterion provides higher values of fatigue life relative to the rate of accumulation of HPD criterion. Although a trend could be established among the fatigue lives obtained by using the two criteria, it was found that the fatigue lives obtained from the rate of accumulation of HPD were consistent and based on the actual measurement of HPD for HMA mixtures.
Highlights
E prediction of fatigue life of hot mix asphalt mixtures (HMA) is an important aspect of pavement design
One criterion is based on the rate of accumulation of the tensile horizontal plastic deformation (HPD) as a function of the number of load repetitions. e other criterion is based on fracture mechanics and takes into account stress intensity factor and the rate of crack growth with respect to the number of load repetitions
It can be seen that the modulus values decrease and the normalized compliance increases with increasing number of load repetitions
Summary
E prediction of fatigue life of hot mix asphalt mixtures (HMA) is an important aspect of pavement design. Many factors affect the fatigue life of HMA pavement such as the tensile strength of the asphalt binder, traffic load, construction practices, aggregate angularity and gradation, relative stiffness of the AC, and the base material and environmental conditions such as temperature and moisture. Many efforts have been made to estimate the fatigue life of laboratory compacted HMA mixtures Such estimates are highly dependent on the criterion used. E damage failure criterion was used based on the analysis of the stiffness modulus, EE, values along the number of load cycles. The fatigue life was de ned as the number of load cycles at which the rapid increase in stiffness modulus occurred. For a displacement or stress controlled test, the change in the displacement or stress along the repeated loading was plotted Based on this criterion, the HMA specimen failed when the displacement or stress values. One criterion is based on the rate of accumulation of the tensile horizontal plastic deformation (HPD) as a function of the number of load repetitions. e other criterion is based on fracture mechanics and takes into account stress intensity factor and the rate of crack growth with respect to the number of load repetitions
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