1. Integrated Fracture Modeling and Testing Approach University of Illinois Research Update
(a) Fracture Behavior
Computer Simulation
(d) Lab Testing
(b) Bulk Material Response
(c) Field Data and Performance E1 E5 1 5
Bill Buttlar, Glaucio Paulino, Eshan Dave, and Sofie Leon
November 18, 2009 – Mn/ROAD Maplewood Lab

2. Review: Task-4
Develop and validate mixture specification for low-temperature cracking:
Level-I: Mixture fracture test
Level-II: Mixture tests + Modeling
Fracture + Creep + CTE
Task-4:
An executable code that can either be run standalone or in conjunction with the MEPDG
User-friendly interfaces for data input and presentation of results
User’s guide with numerical examples that can be used to verify that the program is working properly

3. Level-I, Example (Phase-I)
Mn/ROAD Section-35

4. TCModel vs. New TCModel TCModel Stress Intensity Factor Model
Fracture Model: Paris Law
Crack Amount Model
Amount of cracking is a function of the probability that the crack depth is equal to or greater the thickness of the surface layer
Finite Element Based Thermal Cracking Prediction Model with Cohesive Zone Modeling
Stress Intensity Factor
Far-field stress at depth of crack
Current crack length
Change in crack depth
Change in stress intensity factor
Fracture parameters
Add fracture energy and tensile strength discussion
Bilinear cohesive zone model

5. New TCModel Features Multiple HMA lifts
Viscoelastic bulk material behavior
IDT creep properties
Cohesive zone fracture model
Recommended model from the phase-I results
Uses fracture test results
Finite element analysis engine
Includes mesh generator
Non-linear solver
Similar climatic model as MEPDG

6. New TCModel Status Completed Tasks Tasks underway Future Tasks
Finite element analysis code (testing is underway)
Mesh generator
Tasks underway
Viscoelastic analysis code (formulations are developed, implementation underway)
Temperature boundary condition selection
Future Tasks
Testing of code with all components
Verification and calibration
Integration with User Interface (Visual LTC*)
*Developed under NexTrans supplementary study by Sofie Leon

7. Visual LTC Analysis Tool Developed on NexTrans Supplementary Project
User-friendly graphical user interface (GUI) to capture low temperature cracking characteristics of asphalt concrete
Allows for quick yet sophisticated analysis for practical applications
Currently, it is utilizing TCModel (MEPDG)
New TCModel will be linked as soon as implementation and testing is complete
Add visual LTC is a GUI linking stuff

8. Visual LTC User Types Standard User Advanced User
Similar to existing MEPDG layout
User can easily switch between user types
Standard User
Advanced User
Practitioners
Access to all existing mixes
Default mix properties can be viewed but not changed
Researchers/Developers
Access to all existing mixes
Default mix properties can be viewed and changed
Modify existing mixes and add new mixes
Differentiate between 3rd bullets

9. Visual LTC

10. Visual LTC Results
Crack depth with time
Amount of cracking with time

11. Questions?
Cohesive Zone A B A B t