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The SHRP/Super pave bitumen specification

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The SHRP/Super pave bitumen specification

The Strategic Highway Research Program (SHRP), initiated in the USA in 1987, was a coordinated effort to produce rational specifications for bitumens and  asphalts based on performance parameters. The motivation The Shell Bitumen Handbook was to produce pavements that performed well in service. These pavements were subsequently called ‘Superpave’ (superior performing pavements).One of the results of this work is the ‘Superpave asphalt binder specification’,which categorises grades of bitumen according to their performance characteristics in different environmental conditions. The specification was intended to limit the potential of a bitumen to contribute to deformation, fatigue failure and low temperature cracking of asphalt pavements. The specifications do not distinguish between unmodified and modified bitumens, although some grades can only be achieved through polymer modification of bitumen. It is intended to control deformation, low temperature cracking and fatigue in asphalt pavements. This is achieved by controlling various physical properties measured with the equipment described in this chapter. In this specification, the physical properties remain constant for all grades but the temperature at which these properties must be achieved varies, depending on the climate in which the binder is to be used. For example, a PG 52-40 grade is designed to be used in an environment where the average 7-day maximum pavement temperature is 528C and the minimum pavement design temperature is −408C. Maps of the USA have been prepared showing these upper and lower temperature regimes, thus facilitating binder selection.