Asphalt plays a significant role in pavement quality. The need for high-performance pavements with long service life and low maintenance requirements is the motive behind thorough research and studies of asphalt characteristics. This research focuses on studying all sources of Egyptian asphalt over a span of time using both conventional and Superpave grading techniques in order to characterize asphalt performance and also to answer the question whether the Egyptian asphalts need modification. The results of this research indicate that all Egyptian normal (virgin) 60/70 asphalt samples from different sources failed to meet penetration grading requirements, viscosity grading standards AC-20 (high quality); with minor exceptions, viscosity grading system AC-20 (low quality), and both AR-8000 and AR-1000 Aged Residue grading systems. When Superpave grading system was employed, results indicate that all normal asphalt samples failed to meet the basic requirements (without traffic adjustment) according to the Egyptian climatic requirements for high reliability projects (PG70-10 and PG76-10). The testing results accommodate Superpave requirements for lower levels of reliability and/or lower level of conservativeness. This emphasizes the flexibility and reliability of Superpave grading system as compared to conventional grading systems. On the other hand all modified asphalt samples, using an SBS modifier, passed according to the base high reliability projects and/or high level of conservativeness requirements of the Superpave grading system. Finally it is concluded that Egyptian asphalt should be modified in order to provide satisfactory performance especially for high reliability projects in hot regions with high and/or slow traffic.
Asphalt plays a significant role in a pavement’s ability to withstand thermal and fatigue cracking that contributes to permanent deformation behavior. Temperature is a significant factor that affects asphalt binder and thus the performance and life span of the whole pavement. This paper presents research developing asphalt binder performance grade requirements, according to Superpave, suitable for different climatic conditions all over Egypt. Twenty one weather stations covering Egypt were selected, then after analysis their air temperature data was converted to pavement temperatures using LTPP and performance models. Finally, the converted pavement data were used to propose asphalt binder performance grades (PG) for the various regions of Egypt. The proposed grades range from PG52-10 to PG76-10 depending on the location, the applied model, and the degree of project reliability.
Due to the empirical nature and drawbacks of the conventional procedures, the Strategic Highway Research Program (SHARP) has developed a Superior Performance Asphalt Pavements (SUPERPAVE) mix design procedure. The main objective of this research is to study the applicability of the Superpave in Egypt. This is done by studying aggregate characteristics using both the Superpave and the conventional techniques, investigating the normal (virgin) and SBS modified asphalt characteristics using Superpave, and designing asphalt mixtures comprised of the characterized materials using both the Superpave and the conventional Marshall design methods. Results indicate that Superpave is applicable to Egyptian aggregate with a more restrictive supervision of crushing aggregates and gradations (some gradations may need modifications). Mix design results indicated two main findings; first, most optimum asphalt contents (OAC) determined by the Superpave mix design method are consistently less than OAC determined by the Marshall Mix design method. Second, modified asphalt mixes result in less OAC than normal asphalt mixes according to both Marshall and Superpave mix design methods for both binder and surface layers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.