Pavement Design and Performance Modeling
Characterization of ALF Mixtures Using the Viscoelastoplastic Continuum Damage Model
The primary objectives of this research project are to:
- Verify the time-temperature superposition principle in damaged states for various asphalt mixtures used in the current FHWA Accelerated Loading Facility (ALF) study;
- Characterize the ALF mixtures using the viscoelastoplastic continuum damage model; and
- Predict the performance of various ALF pavements using finite element analysis and the VEPCD model.
A comprehensive mechanistic model is needed to be able to characterize asphalt concrete for a variety of loading conditions experienced in pavements, including temperature, rate of loading, stress state, and damage. In addition, it must encompass all response components: elastic, viscoelastic, viscoplastic, plastic, and fracture. The modeling strategy adopted in this project is based on modeling elastic and viscoelastic behavior using the elastic-viscoelastic correspondence principle based on pseudo strain, the effect of microcracking on the constitutive behavior using continuum damage mechanics, and on the plastic and viscoplastic behavior using a viscoplastic model. The resulting models are integrated by the strain decomposition approach to form the viscoelastoplastic continuum damage (VEPCD) model.
In the National Cooperative Highway Research Program (NCHRP) project 9-19, the VEPCD model has been developed and verified using a single asphalt mixture (Maryland Superpave 12.5 mm mixture), m order for the VEPCD model to be used by the pavement industry, the underlying principles of the VEPCD model need to be verified for a wider range of asphalt mixtures, including modified mixtures. By drawing on the basic research conducted under NCHRP 9-19, this project will verify and refine the VEPCD model by characterizing the various asphalt materials that have been constructed and loaded as test sections under FHWA's Accelerated Loading Facility (ALF). Based on the ALF material testing and performance, the VEPCD model will be refined and further incorporated into a finite element program. By establishing the ability to predict asphalt pavement performance with the VEPCD, the pavement industry will not only be able to improve its asphalt designs, but also to relate the effects of construction practices on the
long-term pavement performance.
