Adaptation of Viscosity Grade System In selection of Asphalt In Sudan

Abstract

This study reviewed the Viscosity Grading System to be adapted in Sudan. It concerns Engineers, Consultants, Contractors, Suppliers and Local Authorities involved. The Asphalt imported to Sudan from different sources (Egypt, Saudi, Iran …etc) according to penetration grade system. The study reviewed the history of grading Asphalt and its uses. This review will assist us to knowing how far Sudan has come to and where it should be in long term so as grading and selecting asphalt are concerned. Asphalt is a thermoplastic material, that is, its stiffness is dependent on temperature, stiffness decreases as temperature increases, this temperature verses stiffness relationship is different for asphalt based on the origin of the Petroleum Crude and/or method of refining. It is clear we should define a test temperature at which the grading will be done and asphalt compared, (Penetration grade system is done on 25⁰c and Viscosity Test is carried out on 135⁰c) The study proved that same penetration grade of asphalt 60/70 from different sources has different stiffness and hence different engineering properties. The study recommended adapting Viscosity Grade System in Sudan for selecting Asphalt to be used in HMA