Using Paving Asphalt Rheology to Impair or Improve Asphalt Pavement Design and Performance

The particular rheological property of a paving asphalt considered in this paper is its temperature susceptibility. Currently neither ASTM nor the American Association of State Highway and Transportation Officials (AASHTO) has a temperature susceptibility requirement in its specification for paving asphalts. For this reason, at the present time paving asphalt temperature susceptibility is far more often used to impair pavement performance than to improve it. Paving asphalt temperature susceptibility is defined in the paper and a method for its measure is indicated. The influence of paving asphalt temperature susceptibility on pavement design and performance in hot climates without frost, and in cold climates with frost, is described. Using the freezing index, °F (°C) days, as the criterion for the minimum temperature at any paving site, a very simple method is illustrated for selecting the optimum paving asphalt or asphalts for surface, binder and base course layers. A set of requirements for paving asphalt temperature susceptibility, which can be added to a paving asphalt specification, is proposed and discussed. Is is shown that by the addition of suitable polymers, the temperature susceptibilities of paving asphalts can be changed dramatically. This development implies that what has been always an asphalt supplier's market could change to an asphalt user's market.