Laboratory evaluation of fatigue damage and healing of asphalt mixtures

The changes in the stiffness of two asphalt concrete mixtures due to temper ature, fatigue damage growth, and healing during rest periods are evaluated using the impact resonance method. The impact resonance method is a means of determining the dynamic modulus of elasticity of a specimen nondestructi vely. The dynamic modulus of elasticity decreases as temperature increases and as microcrack damage growth occurs in the specimen due to fatigue. The impact resonance method also detects increases in dynamic modulus of elasti city after the application of rest periods. A gain in flexural stiffness wa s also observed from measurements and is attributed to closure of microcrac ks or healing during the rest period. The amount of healing or stiffness ga in appeared to increase when specimens were subject to a higher temperature during the rest period. A qualitative study of the two asphalt mixtures sh owed that there is a difference between the two with respect to healing per formance.