Micromechanical Fracture Modeling for Mechanistic Design of Thin Overlays

Asphalt concrete responses to Illinois Flexibility Index Test (I-FIT) were studied using a micromechanical finite element model in order to explore the possibility of linking I-FIT results and overlay design. The model assumed AC composed of two phases: aggregate and mortar. Aggregate was considered linear elastic with material constants reported in the literature, while mortar was linear viscoelastic. Mortar was defined as the combination of binder, air voids, and material passing No. 8 (2.36 mm) sieve. Mixture theory was utilized to characterized mortar as viscoelastic using binder’s dynamic shear rheometer results, elastic properties of fine material, and air voids volume from the mix design. Finally, mortar–aggregate interface was defined by springs with constants from the tensile adhesion test. The micromechanical finite element model was validated with strain fields measured using digital image correlation. The validated finite element model was used to perform a parametric study aimed at determining the effect of gradation and binder properties on the reaction load, opening strains and stresses, and energy around the crack tip. Nine gradations and three binders were studied; ten replicates for each gradation-binder combination were made. In order to create the replicates, a Python script that fabricates artificial gradations and randomly distributes aggregates in the I-FIT geometry was created. It was found that mortar properties, rather than air voids, binder content, or fine material, were heavily correlated to energy and applied load of the I-FIT sample.

• Record URL:
  https://www.chpp.egr.msu.edu/wp-content/uploads/2018/10/CHPP-Report-UIUC4-2018.pdf
• Supplemental Notes:
  • This document was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
• Corporate Authors:

  University of Illinois, Urbana-Champaign

  Urbana, IL  United States  61801

  Center for Highway Pavement Preservation

  Michigan State University
  Okemos, MI  United States 

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Authors:
  • Ozer, Hasan
  • Al-Qadi, Imad
  • Hernandez, Jaime
  • Sawalha, Mohammed
  • Rivera-Perez, Jose
• Publication Date: 2018-4

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Figures; Photos; References; Tables;
• Pagination: 59p

Subject/Index Terms

• TRT Terms: Asphalt concrete; Finite element method; Fracture mechanics; Mechanistic design; Mortar; Overlays (Pavements)
• Subject Areas: Design; Highways; Pavements;

Filing Info

• Accession Number: 01788101
• Record Type: Publication
• Report/Paper Numbers: ICT-18-004, UILU-ENG-2018-2004
• Files: UTC, TRIS, ATRI, USDOT
• Created Date: Nov 16 2021 3:17PM