Hot mix asphalt (HMA) is a composite material which consists of aggregates, air
voids and asphalt materials. The HMA response is typically described to be
viscoelastic-viscoplastic, and its response is a function of temperature, stress/strain rate,
and stress/strain level. Many researches have shown that the viscoelastic response of
asphalt mixtures can be nonlinear once the stress/strain value exceeds a certain threshold
level. This study presents a nonlinear viscoelastic-viscoplastic model for describing the
behavior of asphalt materials under various conditions. A new method is developed in
this study for separating the viscoelastic response from the viscoplastic response.
The first part of this study focuses on the implementation of Schapery nonlinear
viscoelastic model in finite element (FE) using a user-defined material subroutine
(UMAT) within the ABAQUS commercial software. The FE implementation employs
the recursive-iterative integration algorithm, which can improve the convergence and
save the calculating time. The verification of the nonlinear viscoelastic model is
achieved by analyzing (1) the response of asphalt mixtures tested in the Simple Shear Test (SST) at several temperatures and stress levels, (2) the response of unaged and aged
asphalt binders tested in the Dynamic Shear Rheometer (DSR), and (3) the response of
asphalt binders in the multiple stress creep recovery test (MSCR).
In the second part of this study, the nonlinear viscoelastic-viscoplastic
constitutive relationship is implemented using UMAT. The viscoplastic component of
the model employs Perzyna’s theory with Extended Drucker-Prager yield surface which
is modified to account for the difference in material response under compression and
extension stress states. The study includes parametric analysis to illustrate the effect of
nonlinear viscoelastic parameters and viscoplastic parameters on the asphalt mix
response. The capability of the model in describing the fatigue and permanent
deformation distresses of asphalt pavements is illustrated using finite element
simulations.
The constitutive model developed in this study can describe the behavior of
asphalt materials (asphalt binder, asphalt mastic and mixtures) under various testing
conditions. This study also achieved the FE implementation of a nonlinear viscoelasticviscoplastic
constitutive model that can simulate the fatigue and permanent deformation
distresses of asphalt pavement structures.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-3137 |
| Date | 15 May 2009 |
| Creators | Huang, Chien-Wei |
| Contributors | Masad, Eyad |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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