Application of Generalized J-Integral to Crack Propagation Modeling of Asphalt Concrete Under Repeated Loading

Abstract

An energy-based crack-growth model was developed in this study to simulate the propagation of top-down cracking in asphalt pavements. A viscoelastic fracture mechanics approach, the generalized J-integral, was employed to model the crack growth of asphalt concrete. Laboratory fatigue crack propagation tests for three asphalt mixtures were performed at various load levels, frequencies, and temperatures. Disk-shaped specimens with a proper loading fixture and crack growth monitoring system were selected for the tests. It was observed from the tests that the crack-propagation model based on the generalized J-integral was independent of load levels and frequencies, while the traditional Paris law model based on stress intensity factor was dependent on loading frequencies. However, both models were unable to deal with the temperature dependence of the mixtures. The fatigue crack propagation model proposed in this study had a good agreement between experimental and predicted crack-growth lives, an indicator that the energy-based J-integral could be a better parameter to describe fatigue crack propagation of viscoelastic materials such as asphalt mixtures.

Probabilistic prognosis of fatigue crack growth for asphalt concretes

“…A few 7 nondestructive methods to detect cracks and their growth are available for TD cracks [5][6][7]. 8 Once cracks are found, the prediction of the crack growth and the remaining service life are 9 very important for building proper maintenance plans. The growth of a fatigue crack can be 10 modeled by the well-known Paris' law, in which the rate of the crack growth is proportional to the 11 power of the stress intensity factor [8].…”

“…They are generally obtained by the dynamic modulus test 126 [9,59]. The J integral can be calculated by inserting Eqs.…”

“…For a round (or disk-shaped) compact specimen, the geometry 117 function is given by Tada et al [56] 118 . Test setup for the round compact specimen [9].…”

“…∆J was also applied to the fatigue crack growth of large-scale yielding [49]. 82 Recent research shows that the fatigue crack growth equation based on ∆J is also applicable to 83 the fatigue crack growth analysis of asphalt concrete [9,[50][51][52] in which the characteristics of 84 asphalt concretes are homogenized. The crack growth law is expressed as follows…”

“…The application of Paris' law to asphalt concrete, which 12 is distinctly viscoelastic in nature, requires an extension of the classical law. The viscoelastic J 13 integral can be used for fatigue prediction in asphalt pavement instead of the stress intensity factor 14 [9][10][11]. 15 If a crack length is given, the remaining service life can be predicted deterministically using 16 the current crack length.…”