Rheological Properties of Bitumens from the Perspective their Chemical Composition

The quality of bituminous binders is commonly evaluated by the empirical tests. The functional approach to the evaluation of bitumen properties is a trend that has been applied in the last years. The dynamic shear rheometer (DSR) test has been widely used to determine the shear complex modulus of bitumen in the wide range of frequencies and temperatures. A lot of research works were focused on the effect of the chemical compounds of bitumen on the values of the shear complex modulus. The missing information related to the effect of the compound of bitumen on the elastic and plastic part of the shear complex modulus was input for the presented investigation. The significant effect on the elastic part of the complex modulus was determined only at the high temperatures (60 and 80 °C). The aromatics, resins and asphaltenes were identified as the influencing compounds. The important effect was also noted for the resins at the temperatures of 5 and 15 °C. It was also concluded that the effect of the saturates on the elastic part of the shear complex modulus is marginal. The effect of the aromatics and asphaltenes on the plastic part of the shear complex modulus was identified only at the temperature of 80 °C. The effect of these two compounds at other temperatures seems to be unimportant. The significant effect of the resins was stated for the temperatures of 15 °C and 5 °C. Their effect at other temperatures can be supposed as marginal. The negligible effect of the saturates on the plastic part of the shear complex modulus was deducted.

The regression analysis of the chemical composition of the bitumen and the parts of the shear complex modulus at the temperature of 80 °C proved that the frequency of the DSR test can be a factor affecting the level of the relationship between the group composition of the bitumen and its rheological properties.