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Liquid Asphalt / PG Graded Asphalt Binders

Performance graded asphalt binders are specified by the Superpave (Superior Performing Asphalt Pavements) system. Superpave is the result of the $150 million of SHRP (Strategic Highway Research Program) research in the asphalt area to develop a new system for specifying asphalt materials.

A unique feature of the Superpave system is that the specifications are performance based. The tests in the specifications have direct relationships to field performance. The Superpave asphalt binder (performance graded asphalt binder) tests measure physical properties which can be directly related directly to field performance. The performance graded (PG) asphalt binder tests are also run at the temperature extremes which pavements in the field are expected to withstand. The Standard Specification for Performance Graded Asphalt Binder is AASHTO MP-1.

PG asphalt binders are selected to meet expected high temperature and low temperature extremes with a certain level of reliability. An example of a performance graded binder is PG 64-28. PG indicates that it is a performance graded binder. The first two numbers (64) indicate that the binder meets high temperature physical properties up to 64 degrees Celsius. The last two numbers (-28) indicate the binder meets low temperature physical properties down to -28 degrees Celsius. A level of reliability can be determined for a binder selected for use in a particular area using temperature data from a weather station in the area. The level of reliability deemed necessary will need to be determined by the specifying agency.