Development of High Performance Asphalt Mastic using Fine Taconite Filler

摘要

Low temperature cracking is a very serious distress for asphalt pavements built in Northern U.S. and Canada. As temperature rapidly decreases, thermal stresses develop in the restrained asphalt surface layer and, when the temperature reaches a critical value, cracking occurs. A "simple" solution to overcome this problem is to use a very soft asphalt binder with high relaxation properties, which limits the accumulation of high stress and the formation of cracks. However, these types of binder may lead to significant permanent deformation at high temperature (e.g., rutting) and, therefore, cannot be used for real pavement constructions. In this research, the possibility of obtaining stiffer asphalt binders by adding fine taconite filler available in Minnesota was investigated. Two different types of asphalt binders were selected and from each binder, three different types of asphalt mastics were prepared based on the amount (i.e., level) of taconite particles used as filler: 5%, 10% and 25%. Bending Beam Rheometer (BBR) and Dynamic Shear Rheometer (DSR) tests were performed to evaluate the low and high temperature properties of asphalt binder and corresponding mastics. From these experimental works, creep stiffness, m-value, thermal stress and shear complex modulus were calculated and then graphically and statistically compared. It was observed that asphalt mastic containing 5% taconite filler presents similar properties at low temperature and better performances at high temperature compared to the corresponding asphalt binder. On the other hand, asphalt mastics containing higher amount of taconite fines (10% and 25%) are much more brittle compared to the original binder at low temperature, even though higher rutting resistance was observed at high temperature.