Determination of thermal properties of asphalt mixtures

Rational analyses of pavement response require knowledge of the thermal properties of asphalt mixtures. These properties have not been reported thoroughly in the literature and researchers typically depend on assumed values. In the first part of this study, a laboratory test was developed to determine the thermal coefficients of expansion and contraction of several types of asphalt mixtures. The thermal coefficient values were dependent on material type and method of compaction. The coefficients of thermal expansion were slightly larger than the coefficients of thermal contraction. Hot mix asphalt (HMA) showed lower thermal coefficients than the asphalt rubber mix. In the second part of the study, a heat flow computer program was used to simulate lab temperature measurements and calculate the volumetric heat capacity (C) and thermal conductivity (k) values of HMA. No unique C and k values were found, but a linear relationship between C and k values was obtained. A band of possible optimum C and k values was developed. The program was used to estimate the required stabilization times to change test specimen temperatures according to the dynamic modulus (E*) test protocols.