Dan Zollinger Marcello Sanchez Texas A&M University

1. FAA Airport Pavement Working Group Meeting April 24-26, 2012 Climatic Effects in Airfield Pavement Design and Construction Dan Zollinger Marcello Sanchez Texas A&M University

3. Typical Pavement Section

4. Slab Curling and Warping

5. Cracking and Delamination

6. Delamination and Sounding

7. Ultra-Sonic Testing <40% Delaminated ~70% Delaminated

8. Summary: Delamination

9. Slab Cracking

11. Temperature-Cracking

15. Moisture-Based Maturity

16. Monitoring: Lab Cure Monitoring: Field Cure

17. Field Monitoring

19. Compound Ranking

20. Where is the Innovation in Curing Technology? • Equipment Automation? • Rate of application • Pressure/rate of travel • Bar height • Specification & Evaluation? • Monitor application amount • Monitor quality • New Methods and Materials? • Contractor Incentive?

21. Slab Curling and Warping

24. Slab Curling Temperature Gradient Ro Slab Top Tavg Night Day Slab Bottom

27. σnet= σ-ft

28. Application Control

29. Findings Assessment Causes Mitigation PE’s > 0.2 lbs/ft2/h EI’s > 0.800 • Dry and windy weather conditions • Surface wetting behind the paver • Quality of the cure • Compound • Time of placing • Original slab dimensions • Curing quality needs to improve • Potential for problems still exist however • Improved management strategy

30. CODE_BRIGHT Computational Code • Coupled analysis in porous media • Interaction with the atmosphere (Olivella, 1995;Guimarães, 2002; Sánchez, 2004) • Finite element in space • 1D, 2D and 3D elements • Monolithic coupling • Full Newton-Raphson • Finite difference in time • Implicit time discretisation scheme • Automatic time advance • Mass conservative approach for mass • balance equations • User-friendly pre/post processing of data

31. THM behavior in porous medium phases Saturated Medium Unsaturated Medium

32. Solid Liquid Gas Coupled THM Formulation • Balance equations (Olivella, 1994; Guimarães, 2002; Sánchez, 2004) • Mass balance of water (Pl ) • Mass balance of air (Pg) • Internal energy balance ( T ) • Momentum balance ( u)

33. Constitutive equations and equilibrium restrictions Establish the link between dependent and state variables

36. Heater 0.019 m (0.75”) 0.1429 m (6”– 0.75”/2) 0.1334 m (6”– 0.75”) 0.1429 m (6”– 0.75”/2) - 29 Pipes @ 6” (0.1524 m) on each row - Total Pipes: 3-row  29-column = 87 P-401 HMA 0.127 m (5 in.) 1 2 0.5144 m (20.25 in.) Concrete slab (12 in) + Insulation (0.25 in) + Concrete base (8 in) 3 2 3 2 1 4 5 Concrete (2.625 in.) 0.0667 m 1 Dense Grade Aggregate 0.1524 m (6 in.) Pipe (0.75 in.) 0.019 m 2 (0,0) Concrete (2.25 in.) 0.0572 m 3 Insulator (0.25 in.) 0.0064 m 4 Subgrade 1.0 m (39.37 in) Concrete (8.0 in.) 0.2032 m 5 4.572 m (180 in.) (15 ft.)

37. Case 5. Temperature 0.5days

38. Case 5. RH 1.5 days

39. Case 5. 3D effects

40. Formation of Horizontal Delamination Direction of Paving Tensile Stress Evaporation 80~90% rh Stress Distribution Delamination Moisture Distribution ~98% rh Delaminations are more severe in the direction of paving

41. Case 1 vs Case 2 (Temperature) Case 1 Case 2

42. Case 1 vs Case 2 (RH) Case 1 Case 2

43. Where are the Tools? • Paving construction requires curing management • Variable weather conditions • Methods of construction change • Not all curing compounds/methods are created equal • Paving/Slab configurations • Length and width of drag/LT devices • Slab lengths • Subbase types and thicknesses