The Modification of Bituminous Binders by Means of New Generation Polymers

This paper deals with the qualitative and quantitative assessment of the improvement of rheological properties of bitumen modified with the addition of different kinds of new generation polymers, in order to find a polymer which would give the binder itself highest performances, similar to those already measured for the SBS (styrene-butadiene-styrene). In particular, the following polymeric materials were used for the purpose: radial SBS polymer with high, medium and low molecular weight; olefin co-polymer alpha and ter-polymers with dienes - EP(D)M - high, medium and low viscosity; thermo-plastic polymers obtained after polymerisation of ethylene by means of different processes as: VLDPE, LDPE, LLDPE, HDPE and two EVA typologies. Using these polymers, after assuming a traditional bitumen with a 70/100dmm gradation as reference, a 5% in weight modification was carried out by means of a mixer with a mixing head able to prepare a homogeneous and quick solution of polymers into the bitumen. The rheological analysis was conducted at different temperatures with the HAAKE Rheostress 150 rotational rheometer and with advanced interpretative tools as the Black Diagrams and the Cole-Cole diagrams, the results being an interesting comparison of the performances of the different binders, with significant conclusions on the use of such polymers for traditional bitumen modification.