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Barzegar Dissertation5.90 MB
CC BY V4.0, Embargoed Access, Embargo ends: 03/19/2027
Dissertation
CHARACTERIZATION AND MODELING VISCOELASTICITY AND VISCOPLASTICITY OF RECYCLED ASPHALT PAVEMENT (RAP) AS ROADWAY EMBANKMENT MATERIAL
Washington State University
Doctor of Philosophy (PhD), Washington State University
12/2024
DOI:
https://doi.org/10.7273/000007232
Abstract
Recycled asphalt pavement (RAP) consists of asphalt mixtures that have been either unprocessed (e.g., milled) or processed (e.g., screened) and sourced from roadways or other resources. Utilizing RAP is a sustainable practice that can potentially lead to cost savings, environmental preservation, and reduced greenhouse gas emissions, as long as the engineering performance of the roadways incorporating RAP remains uncompromised. This study explores the benefits and drawbacks of using RAP in embankment construction and develops a numerical model to assess RAP's performance under various conditions.
RAP samples from five sources and two conventional soils (as references) for laboratory experiments that included testing for basic soil/RAP characteristics, gradations, moisture-density relationships at different temperatures, permeability, and as well as one-dimensional consolidation tests at different temperatures, dynamic triaxial tests at various temperatures, and direct shear analysis.
The results indicate that while the density and basic characteristics of RAP are similar to soil, temperature effects on RAP must always be considered. RAP exhibits comparable performance to conventional soil under static loading; however, it does not stabilize under traffic loading. Temperature significantly impacts RAP performance. To mitigate settlement issues, thermal preloading of the embankment layer is beneficial. The shear properties of RAP and soil are comparable. The hydraulic conductivity of RAP is considerably higher than that of soil. This difference must be accounted for in the pavement's drainage design.
A numerical model of RAP, employing a viscoelastoplastic approach, is proposed and validated using laboratory data. The nonlinear viscoelastic characteristics of RAP are modeled using a generalized Kelvin-Voigt model. The viscoplastic behavior is characterized by a non-associated flow rule and an isotropic hardening rule. Both the yield function and the flow rule for the viscoplastic model follow the Drucker-Prager framework, but with different sets of parameters. The proposed viscoelastoplastic model was found to be effective in characterizing the unique behavior of RAPs.
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Details
- Title
- CHARACTERIZATION AND MODELING VISCOELASTICITY AND VISCOPLASTICITY OF RECYCLED ASPHALT PAVEMENT (RAP) AS ROADWAY EMBANKMENT MATERIAL
- Creators
- Mohammadreza Barzegar
- Contributors
- Haifang Wen (Chair)Xianming Shi (Committee Member) - Washington State University, Department of Civil and Environmental EngineeringTuncer Edil (Committee Member)Antonio Carraro (Committee Member) - Washington State University, Department of Civil and Environmental Engineering
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Civil and Environmental Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 156
- Identifiers
- 99901195538501842
- Language
- English
- Resource Type
- Dissertation