Rheological behaviour of polymer-modified bituminous mastics : a comparative analysis between physical and chemical modification

Abstract

Mastic, a bitumen/filler blend which naturally forms when bitumen is mixed with aggregates is the actual product used to bind coarse mineral particles in the asphalt mixtures. As a result, the characterisation of mastics is essential to improve the understanding of the response and performance of asphalt concrete pavements. On the other hand, the lack of experimental data concerning the behaviour of mastics and, above all, polymer-modified mastics has been lately claimed. In that sense, this work presents a comparative analysis between the effect that “physical” and “chemical” modification by polymers exert on mastics prepared by blending modified binders with different contents of calcium carbonate, ranging from 65 to 80 wt.%. Tri-block copolymer SBS and a “reactive” isocyanate-based prepolymer were used as modifying agents in the preparation of the binders. Linear viscoelasticy tests revealed that polymer type exerts, at high temperatures, a significant influence on the binder contribution to the overall rheological properties of the resulting mastic.