The primary objective of this research project was an evaluationof the temperature susceptibility and low-temperature fracture characteristics of asphalt cements from heavy crude sources in western Canada. Six samples of asphalt of grades 85/100 and 200/300 formulated from crude oils from Cold Lake, Lloydminster, and Redwater sourceswere tested to determine their physical properties. They were also used to prepare Marshall speciments for testing by the low-temperature indirect tensile test method at temperatures of 0 deg C, -10 deg C, -20 deg C, ad -30 deg C. From the results of the laboratory tests, it is concluded that the Redwater asphalt is the most temperaturesusceptible of the three asphalts studied. It was also confirmed that temperature as well as grade and crude source of asphalts have quite marked effects on the tensile properties of asphalt concrete mixtures. The asphalt cements produced from heavy crude sources of the Cold Lake and Lloydminster areas have been found to perform better at low temperature than those produced from the lighter crude source of the Redwater area. The 200/300 asphalt is also expected to perform better than the 85/100 asphalt. These observations are based on failure strain and stiffness values obtained by means of the indirect tensile test at various temperatures.(A).
Abstract