Studies on the Visco-elastic Characteristics of Asphaltic Bitumens at Low Temperatures

Mechanical behavior of asphaltic bitumens at low temperatures was studied.A relationship between visco-elastic characteristics, statical and dynamical, and Charpy impact resistance values of about 18 kinds of asphalt, with or without filler, was discussed.The results obtained are summarized as follows:1) The Young's moduli of the straight asphalt and blown asphalt are 1-4×1010dyne/cm2 at low temperatures below 0°C.2) With blown asphalt, a plot of elastic modulus against temperatures indicates an inflection point at 10--20°C, and at the same temperature, vibration loss and internal viscosity coefficient show minimum values. From these observations, it is assumed that a transition in the in ternal structure of asphaltoc curs at this temperature.3) The impact resistance value of asphalt shows an inflection point against temperatures ranging from -10°C to -20°C. The values depend mainly upon the Young's modulus below the temperature; they decrease as the modulus increases.