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Multiscale testing-analysis of asphaltic materials considering viscoelastic and viscoplastic deformation

Fine aggregate matrix (FAM) is a phase consisting of asphalt binder, air voids, fine aggregates and fillers. It acts as a primary phase in evaluating the damage and deformation of entire asphalt concrete mixtures. The simplicity, repeatability, and efficiency of the FAM testing make it a very attractive specification-type approach for evaluating the performance characteristics of the entire asphalt concrete mixtures. This study explores a linkage in the deformation characteristics between the two length scales: asphalt concrete mixture scale and its corresponding FAM scale. To that end, a simple creep-recovery test was conducted for the both mixtures (i.e., asphalt concrete mixture and its corresponding FAM phase) at various stress levels. Test results were compared and analyzed using Schapery’s single integral viscoelastic theory and Perzyna-type viscoplasticity with a generalized Drucker-Prager yield surface. In particular, stress-dependent nonlinear viscoelastic and viscoplastic behaviors were characterized in addition to linear viscoelastic deformation characteristics, because the nonlinear viscoelastic and viscoplastic behaviors are significant in asphalt pavements that are subjected to heavy vehicle loads and elevated service temperatures. With a limited scope and test-analysis results at this stage, it was found that there is a strong link between the FAM and asphalt concrete in (linear and nonlinear) viscoelastic and viscoplastic deformation characteristics. This implies that the viscoelastic stiffness characteristics and viscoplastic hardening of typical asphalt concrete mixtures could be estimated or predicted from the simple FAM-based testing-analysis method, which can significantly reduce the experimental-analytical efforts required for asphalt concrete mixtures.

Author(s):

Soohyok Im    
Texas A&M Transportation Institute
United States

Taesun You    
University of Nebraska
United States

Hoki Ban    
Hanyang University
Korea, Republic Of

Yong-Rak Kim    
University of Nebraska
United States