Determination of critical cracking temperature of oil sands at low temperature conditions

This research is intended to predict the viscoelastic behavior of oil sand mixes under low temperature conditions. The oil sand used in this project is a natural, unmodified material that was characterized to explore its unique attributes. A set of oil sand mixes was prepared in the lab with different oil sand content. Field prepared oil sand mixes with different content of oil sand were obtained and both the lab and field mixes were cut into thin beams. The stiffness and creep compliance values of the specimens were obtained through the BBR testing of samples at low temperatures of -18C, -12C and -24C. Time-temperature super position principle was applied in order to obtain a master creep stiffness curve for the oil sand mixtures. With the help of Laplace transformation, relaxation moduli for the mixtures were predicted. Based on the relaxation moduli and strain values, the thermal stresses of the oil sand mixtures were determined. After the thermal stress values were determined, the plots between temperature and stress were drawn. These plots provided the cracking temperatures for different percentages of oil sands in the mixes, which were used in the study. The key findings of this research are that the relaxation modulus of the oil sand mix increases with decrease in oil sand content and the critical cracking temperatures of the oil sand mixes are higher than that of the actual low pavement temperatures in Utah.