Characterization of Asphalt Binder Resistance to Permanent Deformation Based on Nonlinear Viscoelastic Analysis of Multiple Stress Creep Recovery (MSCR) Test

摘要

The multiple stress creep recovery (MSCR) test has been developed and used recently to characterize the resistance of asphalt binders to permanent deformation. In this test, an asphalt binder is subjected to creep loading using different stress levels with recovery periods between stresses. The current analysis method of the MSCR test uses the strain accumulated at the end of the test to derive an index describing the resistance of asphalt binders to permanent deformation. However, the limitation of this analysis method is that the accumulated strain does not necessarily consist of only permanent strain but it can also include viscoelastic strain that might not fully recover given the limited recovery time used in the test. The viscoelastic strain would fully recover provided that enough time is allowed for this to happen.rnThis paper presents a Plasto-Viscoelastic approach to analyze the MSCR test results. The approach relies on identifying the viscoelastic response (recoverable with time) and the actual permanent strain (irrecoverable). A nonlinearrnviscoelasticity theory is employed in this approach to analyze the recoverable response. The permanent strain is used to develop an index by which to evaluate the resistance of asphalt binders to permanent deformation. The new analysis approach is corroborated by analyzing asphalt binders that have been used as part of the Accelerated Loading Facility (ALF) experiment of the Federal Highway Administration (FHWA). The new permanent deformation index shows excellent correlation with the performance of the ALF sections.