Nonlinear thermal expansion and contraction of asphalt concrete

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.