Benzoxazine-modified asphalts

Abstract

The use of polymers for modification of asphalt is an attempt to prolong the service life and improve the performance of asphalt particularly for road pavement applications. This research aims to study mechanical and thermal properties of asphalt modification by bisphenol A based benzoxazine resin. The 60/70 penetration grade asphalts were modified by varying the amount of benzoxazine resin at 1wt%, 3wt%, 5wt%, 7wt% and 9wt%. The suitable mixing condition was achieved by mechanical mixing for 1 hr at 80°C and a mixing speed of 500 rpm with a stirrer followed by curing for 1 hr at 190°C. The storage modulus increased when benzoxazine contents increased and the glass transition temperature (Tg) of benzoxazine-modified asphalt increased to 4.4°C from -14.3°C of the unmodified asphalt. The degradation temperature of benzoxazine-modified asphalt increased to 380°C from 354°C of unmodified asphalt. Rheological properties as storage shear modulus, loss shear modulus and viscosity at 60°C increased when benzoxazine contents increased. The maximum temperature of rutting parameter (G*/sinδ) increased from 65°C to 84°C and specific gravity increased from 1.034 to 1.053 when benzoxazine contents increased. Morphology of benzoxazine resin and asphalts blend revealed that benzoxazine fraction to disperse as small particles in the asphalts. Softening point of the benzoxazine-modified asphalt increased with increasing the benzoxazine resin contents while the penetration depth decreased when the benzoxazine ratio increased. Appreciable decrease in formation of rutting, bleeding and cracking are thus expected to be achieved by the use of the benzoxazine-modified asphalts.