Permanent Deformation Characterization of Asphalt Concrete Using a Viscoelastoplastic Model

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Title: Permanent Deformation Characterization of Asphalt Concrete Using a Viscoelastoplastic Model
Author: Zhao, Yanqing
Advisors: Y. R. Kim, Committee Chair
Abstract: The objective of this research is to develop an accurate and advanced material characterization model for predicting response of asphalt mixtures subjected to compression loading. The first step of the modeling is to check the validity of the time-temperature superposition principle for asphalt concrete with growing damage and viscoplastic strain in the compression state. Constant crosshead rate compression test results are used to construct the stress-log reduced time master curves for various strain levels. Research results indicate that asphalt concrete with growing damage remains thermorheologically simple (TRS), and that the time-temperature shift factor is only a function of temperature and is independent of the strain level. The model encompasses the elastic, plastic, viscoelastic, and viscoplastic strain components of asphalt concrete behavior and the effects of test conditions such as temperature and loading rate on the major strain components. The modeling approach is to model each response component separately and then integrate the submodels to obtain the final viscoelastoplastic model. The viscoelastic component, including elastic strain, is modeled based on Schapery's continuum damage theory and work potential theory, whereas Uzan's strain hardening model forms the basis of the viscoplastic model that also includes the plastic strain component. The testing program required for calibrating the viscoelastoplastic model is composed of small-strain complex modulus testing at various temperatures and frequencies to determine linear viscoelastic properties, constant crosshead rate testing at low temperatures/fast loading rates for viscoelastic modeling, and repeated creep and recovery testing at high temperatures for viscoplastic modeling. The developed viscoelastoplastic model performs well in predicting material responses up to peak stress.
Date: 2002-12-03
Degree: PhD
Discipline: Civil Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/3629


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