The performance of polymer modified bituminous mixtures.

The use of polymers in bituminous materials has been gaining popularity over the last decade. Despite their superiority in enhancing the performance of bituminous mixtures, problems have been experienced due to limitations on the applicability of currently available assessment techniques.This thesis is concerned with the mechanical behaviour of polymer modified bitumens and the performance of polymer modified bituminous mixtures. The first part of the thesis presents different pavement distresses and the importance of using polymer modified binders to improve the performance of bituminous mixtures. The second part deals with identification of properties of polymer modified binders and their mixtures by using dynamic mechanical analysis. The third part attempts to develop a novel technique for assessing resistance to permanent deformation of HRA mixtures using a dissipated energy method.Some polymer modified binders are susceptible to storage instability. However, this work has demonstrated that certain empirical tests are unsuitable for assessing the temperature susceptibility and storage stability of polymer modified binders. Viscoelastic behaviour of bituminous materials is better presented by dynamic mechanical analysis. The dynamic mechanical analysis provides a basis for explaining the unsuitability of some empirical tests on polymer modified binders.Determination of dissipated energy during creep testing enables more comprehensive and accurate assessment of the resistance to permanent deformation of Hot Rolled Asphalt (HRA) mixtures. This study reveals that assessment of the resistance to permanent deformation based upon permanent strain rate in the linear region is in good agreement with the dissipated energy method. The end of the linear region, N1, can be accurately determined by the dissipated energy method and provides a confidence that analysis will always be conducted in the linear region. As expected, polymer modified mixtures are superior to the unmodified ones in their resistance to permanent deformation which confirm by the wheeltracking test, but was not evident from the Marshall tests.