Application of Creep and Fatigue Tests on Hot Asphalt Mixes

An asphalt concrete pavement should be designed to provide a durable, skid resistance
surface under in service conditions. Also, it is essential to minimize cracking and rutting in the
asphalt concrete layers. To fully utilize each material in an economical design, a pavement should
generally have a reasonable blanaced design between the rutting and fatigue modes of distress.
The purpose of this paper is to examine both fatigue and deformation characteristics of four types
of asphalt concrete mixes produced by different mixing procedure. Fatigue properties are
measured using a rectangular slab specimens resting on a rubber (elastic) subgrade using the
wheel tracking machine under dynaminc loading condition. Deformation characteristics of the
mixes are determined using the shell creep test for 1 hour at ambient temperature. The contact
stress is taken in tlie range of 6.25 psi to 100 psi which simulate a wide range of tire pressure. The
results of this study indicate that, under high stress level the mixes of higher Marshal stiffness
show higher resistance to creep deformation and fatigue cracking. While under low stress level
the mixes of higher Marshal stability show higher resistance to creep deformation. For all
investigated mixes, the stress - strain relationships are almost linear under stress-level below 25
psi for all test loading times. While under high stress levels, between 25 psi and 50 psi the rate of
increase in creep strain is significantly greater than that from 50 psi to 100 psi