Viscoelastic behaviour of asphalt modified by grafted tri-block copolymers: predictions of fractional rheological models

Abstract

Blends of asphalt with three maleic anhydride-modified triblock copolymers are prepared and analysed in detail for potential use in pavement construction. These blends are compared with those made with the copolymers without chemical modification. The use of grafted polymers improves the conventional properties of blends made with the asphalt and precursor polymers, such as penetration, softening point, storage stability at high temperature and the rheological properties. In addition, blends made with the chemically modified polymers present biphasic morphology with improved dispersion and interconnected phases. Semi-empirical models corresponding to a constitutive equation with fractional derivatives are proposed to predict the linear viscoelastic properties of the blends using few parameters for each temperature. The fractional Kelvin, fractional standard linear solid and fractional Maxwell models are shown to predict appropriately the linear viscoelastic properties from 25 to 75°C at frequencies from 0.1 to 100 rad/s.

Keywords::

• asphalt
• grafted polymer
• fractional rheological models
• morphology
• viscoelasticity