Influence of the processing conditions on the rheological behaviour of polymer-modified bitumen

Mixing polymers into bitumen has important consequences on the engineering properties of bituminous binders. Thus, structural and chemical changes may be observed during processing of polymer-modified bitumens. Chemical compatibility and processing conditions are crucial to obtain suitable properties. Most polymers occur to be insoluble, in some degree, in the bitumen matrix, and phase separation may result. Polymer stabilization can be achieved by mechanical dispersion of the modifier and swelling by compatible components in the maltene fraction. This paper deals with the influences that processing variables exert on the rheological properties of polymer-modified bitumens. From the experimental results obtained we may conclude that a rotor-stator mixer device enhances the rheological properties of binders prepared with high-density polyethylene, low-density polyethylene, ethylene-propylene-diene monomer, and their blends, as compared to a stirred tank device. (C) 2003 Elsevier Science Ltd. All rights reserved.