Predicting thermal cracking of asphalt pavements from bitumen and mix properties

The objective of this study was to develop approximate relationships for prediction of the rheological properties and tensile strength of asphalt concrete with conventional bitumen binder to address the low-temperature cracking analysis. The parameters of modified Christensen-Anderson-Marasteanu model for relaxation modulus of bitumen were related with its penetration index and softening point by approximate formulas based on Van Der Poel's nomograph for determining bitumen stiffness. Hot mix asphalt relaxation function has been described by the Christensen-Bonaquist model. Hot mix asphalt tensile strength as a function of loading time and temperature was related to the bitumen stiffness by equation based on Heukelom's data and the Molenaar-Li empirical formula. The strength of hot mix asphalt has been also studied by performing tensile tests at constant strain rate and temperatures. The results were analysed considering the calculated stress increase with temperature drop at various cooling rates. Critical temperature was estimated from comparison of thermal stress and tensile strength of asphalt concrete at constant stress rate.