Abstract:

Four- point bending beam fatigue tests of three kinds of graded asphalt mixtures were carried out in thestrain control mode,and two criteria for fatigue life prediction,namely the catastrophe point of the relative changerate of dissipated energy (Criterion 1) and the stiffness modulus decreasing to 50% of the initial stiffness modulus(Criterion 2),were compared.Then,two fatigue life prediction models respectively corresponding to the two crite-ria were constructed.The results show that (1) the initial stiffness modulus of the mixture decreases with the in-crease of strain level and nominal maximum particle size; (2) when Criterion 1 is used as the failure criterion,thesame mixture mostly destroys with the same stiffness modulus at different strain levels,the destruction stiffnessmodulus of different mixtures decreases with increase of nominal maximum particle size,and the predicted fatiguelife is longer than that predicted by Criterion 2; (3) the fatigue life of asphalt mixture significantly decreases withthe increase of the strain level and the nominal maximum particle size; and (4) the fatigue life prediction modelcorresponding to Criterion 1 is of higher accuracy.

Key words: asphalt mixtures, fatigue life, strain control, dissipated energy, relative change rate, stiffness mo-dulus, failure criterion