Fatigue Damage of Asphalt under Compound Loading

The results of an investigation suggest that, for the various forms of compound loading investigated, i.e., (1) all other variables except stress level maintained constant; (2) all other variables except temperature maintained constant; and (3) both stress and temperature level varied, fatigue life is predicted with acceptable accuracy by a linear cumulative damage rule. Tests were carried out in the controlled stress mode in rotating bending fatigue machines. Because of the inherent variability of the material, the ability of a linear cumulative damage rule to predict compound-loading fatigue life is assessed over a range of probability of failure levels. The results indicate that there is reasonable probability that the cumulative cycle ratio at failure will be equal to or greater by an acceptable amount than unity.