Development of a DSR Test Method to Determine Low Temperature Properties

The dynamic shear rheometer (DSR) is the critical apparatus used in the Superpave performance-graded (PG) binder system for high and intermediate temperature, while the bending beam rheometer (BBR) is a core equipment for low temperature. During the Strategic Highway Research Program (SHRP), DSR with parallel plate geometry was considered for the low temperature PG system, but it was not selected because it was recognized that DSR measurements produced instrument compliance errors. Thus, SHRP developed the bending beam rheometer (BBR) to measure the low temperature rheological properties of asphalt binder. Although the BBR method has been an official approach to measure low temperature properties, it has several operation drawbacks including a long fabrication and testing time, and it requires large amounts of binder to fabricate each testing specimen and is very labor intensive. Thus, a clear benefit is expected is the current BBR method can be supplemented or replaced by an alternative method to advance efficiency-accuracy of binder grading-evaluation program.