The results presented in this paper are those obtained with around twenty proprietary binders consisting of pure bitumens and binders modified with elastomers and plastomers. All these binders were characterized by means of conventional tests (Fraass breaking point, penetration, and ring-and-ball softening point), thus allowing the plasticity range to be calculated. They were also characterized by the direct tensile stress method proposed by the SHRP, for their low-temperature behaviour, and by means of dynamic rheometer for their rheological behaviour at medium and high temperatures. Interpretation of all these results makes it possible to: (1) accurately determine the relationship between the Fraass relationship between the Fraass breaking point, the 1% elongation temperature limit under SHRP conditions, and the temperature at which the stiffness modulus is 300 MPa (tensile test); (2) qualify the rheological behaviour of modified binders at medium and high service temperatures, and to compare the merits of elastomers and plastomers; and (3) redefine a plasticity range between the temperature at which the stiffness module is G*/sin delta = 1 kPa (maximum service temperature of bituminous binders) and the 1% elongation temperature limit (minimum service temperature), and to compare it to the conventional plasticity range between the ring-and-ball softening point and the Fraass breaking point, in the case of pure bitumens, elastomer-modified and plastomer-modified bitumens. (A).
Abstract