Asphalt Cements: Pen-Vis Number and Its Application to Moduli of Stiffness

Abstract

Because of the false softening points of many Canadian asphalts due to the waxy crude oils from which they are derived, highly erroneous values for Pfeiffer's and van Doormaal's penetration index as a quantitative measure of the temperature susceptibility of asphalt cements occur. Consequently, it has been necessary to develop a different quantitative measure for temperature susceptibility, pen-vis number, which is based on an asphalt cement's penetration at 77°F (25°C) and viscosity in centistokes at 275°F (135°C). The development of the pen-vis number of an asphalt cement and its application to the determination of moduli of stiffness of asphalt cements and asphalt paving mixtures are described.