Evaluation of Repeated Creep and Recovery Test Method as an Alternative to SHRP+ Requirements for Polymer Modified Asphalt Binders

The SuperpaveTM Performance Graded (PG) asphalt binder system is now being universally used in the United States. Some states also require additional empirical tests such as elastic recovery, lowtemperature ductility, force ductility, toughness and tenacity, and other variations. These additional tests, referred to as SHRP+ specifications, are employed to ensure that asphalt binders contain elastomeric modifiers. The Federal Highway Administration (FHWA) has been evaluating the Repeated Creep and Recovery Test (RCRT) as a possible alternative to the various SHRP+ tests. In addition to characterizing fundamental properties, the RCRT is an easy to use performance related test. The RCRT is conducted at the high PG temperatures and takes approximately the same amount of time as the current Superpave Dynamic Shear Rheometer (DSR) test. Comparison of test results between the RCRT and elastic recovery has shown a good correlation for many binders. A draft standard practice is available and is being used in the United States by various user producer groups and lead state agencies to verify the multiple stress RCRT criterion. This paper describes the multiple-stress RCRT in detail and presents the results of data analysis. Recommendations are made for implementation of this test method as a possible replacement of the SHRP+ tests. For the covering abstract of this conference, see ITRD number E215112. (A)