1. A Partnership in Research and Outreach David A. Lange, CEAT Director Department of Civil and Environmental Engineering

2. CEAT Overview History Began in 1995 as FAA COE (Barry Dempsey, Director) Original focus on pavements Broadened to wildlife hazards, lighting technology Partnership with O’Hare Modernization Program began in 2004

3. OMP, FAA and UIUC in partnership O’Hare Modernization Program Federal Aviation Administration Subgrade issues Materials & Pavements Outreach Subgrade & pavements Wildlife issues Anti-icing Outreach

4. Our OMP Partner $6.6B program –35 miles of runways, taxiways –2.2M cu yds of PCC –29M cu yds of earthwork Modern, parallel runway configuration Massive earthmoving, construction, hydraulic, environmental impact challenges

5. OMP objectives Technical objectives –Illuminate technical issues at O’Hare –Lead to cost-effective solutions Outreach objectives –Reach contractor community –Deliver educational programs

6. OMP Projects Technical –Subgrade stabilization -- Erol Tutumluer & Marshall Thompson –Raw Materials -- Leslie Struble –PCC Pavement -- Jeff Roesler & David Lange Outreach –College support is vital -- Minosca Alcantara, Eve Earles, John Popovics –Focus: MBE/WBE, Contractors, Education

7. FAA Projects Pavement Research Program –Moisture curling of concrete slabs for airfield applications D.A. Lange and J.R. Roesler –Materials Testing for NAPTF Base/Subbase and Subgrade Layers E.Tutumluer –Fatigue and Fracture Behavior of Airfield Concrete Slabs J.R. Roesler, S.P. Shah, B. Mu –Anti-icing Coating Self Cleaning Properties and Wearing Characteristics Study at ORD B.J. Dempsey –Fatigue in Airport Pavements S.H. Carpenter –Design of Flexible Overlay Systems for Asphalt Pavements: Phase II Advanced Model Development W.G. Buttlar

8. FAA Projects (cont.) Wildlife Research Program –Bird Strike Advisory System Ed Herricks Outreach Program –Summer COE Internship Program for Minority Graduate Students B.J. Dempsey

9. Moisture curling project Basic driving force –Internal capillary stresses imposed under partial saturation Water vapor in pores Water layer contacting solid phases RH defines magnitude of stress felt by solid Material modeling –Hygrothermal forces, shrinkage, creep –Time dependence, inter-dependence Structural modeling Validation using lab tests & NAPTF slab tests

10. Two cases Highly restrained slab  Cracking Low restraint in slab  Curling + Wheel Load  Cracking

11. UIUC RH-temperature measurement system

12. Digital sensor packaged for placement in fresh concrete Sensirion digital RH/Temp sensor –Absolute accuracy ~±2% RH and 0.5° C Packaging system allows placement in fresh concrete –Small plastic tube with Gore-Tex cap Gore-Tex allows vapor transmission while blocking liquid water

13. Typical RH gradient Different depths from drying surface in 3”x3” concrete prism exposed to 50% RH and 23 o C

14. Symmetrically drying concrete prism Surface RH assumed to be ~ambient

15. Simple model for shrinkage strains 76mm x-section Superposition of strains TT  sh

16. Free shrinkage stress gradients 3 days age (2 days of drying) Model predicted damage zones

17. NAPTF SINGLE SLAB 15 ft x 15 ft x 11 in. SINGLE SLAB

18. MSC Patran Geometric Modeling EACON(UIUC) Stress Analysis MSC Patran Post Processing EACON_export.pcl EACON_import.pcl Matlab Engine Sparse Matrix Solver Stress Analysis Code for Early Age Concrete NOTE: EACON is * a 3D Nonlinear FEA code written in C++ * using 20-node solid and 2-node spring element Unique feature: EACON handles time and stress dependent material properties NUMERICAL MODELING

19. NUMERICAL ANALYSIS Material Properties Need for Numerical Analysis ■ “Instantaneous” properties  E(t), v, fc(t), ft(t) ■ “Delayed” property  Creep ■ Hygrothermal strain  Volume change due to Temperature & Humidity

20. X Z Y X fixed Non-linear spring ( Z only) Y fixed NUMERICAL PRACTICE Geometry and Boundary Conditions X,Y,Z fixed 7.5 ft 11 in.

21. Deformation & Ground Contact Age = 1.5 days, 500xAge = 3 days, 500x NUMERICAL PRACTICE Virtual material & surface drying scenario

22. Max. Principle Stress at edge ( Age = 3.0 days ) 460psi 0 psi NUMERICAL PRACTICE Virtual material & surface drying scenario

23. NAPTF SINGLE SLAB ANALYSIS Lift-up Displacements at corner & edge Virtual material & measured temperature and humidity history A B

24. Summary We want to provide: –a more complete understanding of mechanisms –new sensor technology –accurate, complete material models –useful software tool for analysis Results relate to material selection (e.g. high FA concrete)