Asphalt concrete for paving roads is a viscoelastic material. In the predic
tion of thermal stress in asphalt pavements, the thermal expansion-contract
ion property of the material is required. In current practice, thermal expa
nsion-contraction is assumed to be a linear function of temperature, and a
constant thermal coefficient is used. The fact that a viscoelastic material
may have a glass transition temperature and the thermal property may have
a discontinuity at the glass transition temperature has not been considered
. This study investigates the thermal nonlinearity of asphalt concrete. In
this research, the thermal expansion-contraction was continuously measured
on a single type of asphalt concrete in the temperature range from +40 degr
ees C to -40 degrees C. It was found that the thermal expansion-contraction
was a continuous nonlinear function of temperature, resulting in a variabl
e thermal coefficient. Evaluations of the effect of the nonlinearity indica
ted that the assumption of thermal linearity can result in moderate errors
in stress prediction in asphalt pavements.