Refinement of the Superpave specification parameter for performance grading of asphalt

The Superpave specification parameter \G*\ /sin delta for high temperature performance grading of paving asphalts has not been found to be adequate in rating various binders, especially some polymer-modified ones, for their r utting resistance. This has led researchers to seek other possible paramete rs that may better relate to rutting resistance and also to search for ways to improve the existing parameter \G*\ /sin delta so that it is more sensi tive to pavement performance. Some researchers have suggested the repeated creep and recovery test, while others have used a semiempirical approach as a means to refine the existing Superpave specification parameter. The pres ent work revisits the proposed refinements of the Super-pave specification parameter and shows that the semiempirical approach involving curve-fitting of experimental data is not necessary if the derivations are based on fund amental concepts. The final equations obtained through a theoretical develo pment are verified using part of the same experimental data that were used by the earlier researchers.