No abstract

No abstract

No abstract

The viscosity functions of several polymer-modified asphalts (PMAs) were studied at different temperatures in steady-state rate sweep tests. The materials were obtained by mixing different base asphalts with either styrene-butadiene-styrene (SBS), ethylenevinylacetate (EVA) or reactive ethylene terpolymers (RET). The first two polymers form a physical network that is swollen by the asphalt, while the latter is functionalized with glycidylmethacrylate (GMA) and can crosslink and/or chemically bond with the molecules of asphaltenes. In the presence of SBS or EVA, at certain temperatures, the viscosity curves exhibit a Newtonian behavior at low shear rates, followed by two distinct shear-thinning phenomena. In some cases, the first shear-thinning is preceded by a small shear-thickening region. Similar phenomena are not present in the viscosity curves of the RET-modified asphalts and can be related to a temporary nature of the physical polymer network.

The effect of the addition of clay as a third component in polymer modified asphalts has been investigated. After a preliminary investigation on the binary asphalt/clay and polymer/clay blends, the tertiary blends were prepared by adding the clay and polymer to the asphalt, either separately or in the form of a premixed master batch. Intercalated nanocomposites with comparable interlayer distances and glass transition temperatures were obtained in both cases. However, the results show that the mixing procedure significantly affected the final rheological properties. The master curves built in the linear viscoelastic range and represented in both the frequency and the temperature domains help to visualize and evaluate such differences. Suggested Reviewers:Dear Professor Vancso, I'm submitting the new version, revised according to referees' suggestions. I would like to thank you and the referees for helping us in improving the quality of the paper. AbstractThe effect of the addition of clay as a third component in polymer modified asphalts has been investigated. After a preliminary investigation on the binary asphalt/clay and polymer/clay blends, the tertiary blends were prepared by adding the clay and polymer to the asphalt, either separately or in the form of a premixed master batch. Intercalated nanocomposites with comparable interlayer distances and glass transition temperatures were obtained in both cases. However, the results show that the mixing procedure significantly affected the final rheological properties. The master curves built in the linear viscoelastic range and represented in both the frequency and the temperature domains help to visualize and evaluate such differences.

No abstract

No abstract

Polymer modified asphalt is an highly temperature sensitive material. To obtain the master curves of dynamic material functions, for this material, it is necessary to perform the testing over the temperature interval from -30˚C to at least 90˚C. Since in this temperature range the polymer modified asphalt undergoes the transition from a glass-like to a Newtonian-like material, the benefit of using three testing geometries is studied here. The geometries used were: torsion bar (for the low temperatures), plate-plate (for the mid range temperatures) and bob and cup (for the high temperatures). The advantage of the combination of these three geometries is discussed. Stress and strain controlled rheometers were used to conduct all dynamic experiments. Master curves obtained by these geometries cover up to 20 decades of the reduced frequency.