Concrete (PCC) Mixture Designs for O’Hare Modernization Program

1. Concrete (PCC) Mixture Designs for O’Hare Modernization Program Principal Investigators Prof. Jeff Roesler Prof. David Lange PROJECT GOAL Investigate cost-effective concrete properties and pavement design features required to achieve long-term rigid pavement performance at Chicago O’Hare International.

2. Acknowledgements Principal Investigators • Prof. Jeff Roesler • Prof. David Lange Research Students • Cristian Gaedicke • Sal Villalobos • Rob Rodden • Zach Grasley Others students • Hector Figueroa • Victor Cervantes

3. Project Objectives • Develop concrete material constituents and proportions for airfield concrete mixes • Strength • volume stability • fracture properties • Develop / improve models to predict concrete material behavior • Crack width and shrinkage • Evaluate material properties and structural design interactions • joint type & joint spacing (curling and load transfer) • Saw-cut timing

4. FY2005-06 Accomplishments www.cee.uiuc.edu/research/ceat • Tech Notes (TN) - • TN2: PCC Mix Design • TN3: Fiber Reinforced Concrete for Airfield Rigid Pavements • TN4: Feasibility of Shrinkage Reducing Admixtures for Concrete Runway Pavements • TN11: Measurement of Water Content in Fresh Concrete Using the Microwave Method • TN12: Guiding Principles for the Optimization of the OMP PCC Mix Design • TN15: Evaluation, testing and comparison between crushed manufactured sand and natural sand • TN16: Concrete Mix Design Specification Evaluation • TN17: PCC Mix Design Phase 1

5. FY2006 Accomplishments www.cee.uiuc.edu/research/ceat • Tech Notes (TN) - • TN21: An Overview of Ultra-Thin Whitetopping Technology • TN23: TN23: Effect of Large Maximum Size Coarse Aggregate on Strength, Fracture and Shrinkage Properties of Concrete • TNXX: Effects of Concrete Materials and Geometry on Slab Curling • TNYY: Concrete Saw-Cut Timing Model • TNZZ: Functionally Layered Concrete Pavements

6. Presentation Overview • Large-sized coarse aggregate mixtures • Saw-cut timing model • Slab Curling • Field Demo Project • Recycled Concrete Aggregate

7. Aggregate Interlock Joints • Reduced LTE with small maximum size CA Dowels deemed necessary Crack width, cw

8. Larger maximum size CA Aggregate Interlock Joints Larger aggregate top size increases aggregate interlock and improves load transfer Crack width, cw

9. Why Larger Size Coarse Aggregate? • Potential benefits • Less paste  lower cementitious content • Shrinkage • Higher toughness • Fracture and crack propagation resistance • Increase roughness of joint surfaces • Increased load transfer between slabs • Reduced # of dowels • Durability (??) • D-cracking Cost - Effectiveness

10. Experimental Design • Effect of aggregate size (1.0” vs. 1.5”) • Effect of 1.5” coarse aggregate: • Total cementitious content: • 688 lb/yd3, 571 lb/yd3, 555 lb/yd3 and 535 lb/yd3 • Water / cementitious ratio: • 0.38 versus 0.44 • Fly Ash / cementitious ratio: • 14.5% versus 0% • Effect of coarse aggregate cleanliness

11. Mix Design Results

12. Phase II Mix Summary Effect of larger-size coarse aggregate on strength Larger-size coarse aggregate

13. Drying Shrinkage – Phase II Effect of larger-size coarse aggregate on shrinkage

14. Fracture Energy Results-Phase II Effect of larger-size coarse aggregate on fracture properties • Age = 28-days

15. PCC Mix Design – Phase II • Summary* • Larger aggregates reduce strength by 20%, but… • 28-day GF similar  similar cracking resistance • Larger aggregates reduce concrete brittleness • 1-day fracture energy  with larger MSA  greater joint stiffness / performance • No significant shrinkage difference • TN23 – April 2006 *Roesler, J., Gaedicke, C., Lange, Villalobos, S., Rodden, R., and Grasley, Z. (2006), “Mechanical Properties of Concrete Pavement Mixtures with Larger Size Coarse Aggregate,” accepted for publication in ASCE 2006 Airfield and Highway Pavement Conference, Atlanta, GA.

16. Saw-Cut Timing Model a d • Concrete E and fracture properties(cf ,KIC)at early ages. • Develop curves of nominal strength vs notch depth for timing. • Notch depth (a) depends on stress, strength, and slab thickness (d) • Stress = f(coarse aggregate,T,RH)

17. Saw-Cut Timing and Depth a d • Saw cut depth / timing – EXPERIENCE • Fracture properties at early ages • Critical Stress Intensity Factor (KIC) • Critical Crack Tip Opening Displacement (CTOCC) form this type of specimen • Wedge Splitting Test (WST) • need geometric factors

18. Saw-Cut Timing and Depth • Process • Concrete Mix • Aggregate size • Cementitious content Crack Propagates FRACTURE PROPERTIES Wedge Split Test FEM Model Saw Cut Depth Model

19. Wedge Split Testing Notch detail 80mm 40mm 80mm 30mm 200 mm 57mm b a = a/b t a 2mm 205mm 200 mm • WST setup and specimen

20. Saw-Cut Timing and Depth • FEM Model • Special Mesh around crack tip • Q8 elements • Symmetry and BC considerations 200 mm 100 mm

21. Saw-cut timing and depth • FEM Model Results • Determination of Fracture parameters

22. Saw-cut timing and depth • FEM Model Results • Determination of Fracture parameters

23. Saw-Cut Depth Model • SEM Model (Bazant) Nominal Strength vs Notch Depth Chart

24. Saw-cut timing and depth • Mix proportions • Aggregate gradations • Concrete

25. Concrete Fracture Properties • Critical Stress Intensity Factor (KIC) • Critical Crack Extension (cf)

26. Curling Stress in Concrete Slab • Westergaard Slab Curling Saw cut Depth

27. Low Cementitious Content • Saw Cut Depth Charts

28. High Cementitious Content • Saw Cut Depth Charts

29. Summary of Notch Depth Requirements

30. Saw-cut timing and depth • Summary • Saw cut depth increases with concrete age • dramatic increase in depth after 10 to 12 hr. • Larger maximum aggregate size increases saw cut depth • High cementitious materials especially

31. Curling Questions • How does shrinkage effect slab size? • What are the combined effect of moisture/temperature profile? • What is the role concrete creep? • How do other concrete materials behave – FRC & SRA?

32. Slab Curling  Stress  s s s s Time • Effects of materials and slab geometry on moisture and temperature curling after Grasley (2006) & Rodden (2006)

33. Field vs Lab Field Lab

34. RH Profile - Lab

35. STD Cube Moisture Stresses

36. Summary of Curling • Moisture profile effects • Temperature • Set temperature • Shrinkage Reducing Admixtures • Fiber Reinforced Concrete

37. Joint Type Analysis h How can we choose dowel vs. aggregate interlock joint type & joint spacing? • Need to predict crack width & LTE • Shrinkage, zero-stress temperature, creep • Aggregate size and type (GF) • Slab length & base friction If we use aggregate interlock joints there is a significant cost savings

38. Field Demo Project

39. Joint Opening Measurement

40. Two week joint opening

41. Concrete Free Shrinkage

42. Crack Width Model Approach Step 1: Predict crack opening, w Step 2: Predict differential deflection, δdiff Step 3: Determine LTE Step 4: Acceptable LTE? Inputs: RH, T, L, E, , C Inputs: w, CA topsize,  Inputs: δfree, δdiff,  Inputs: FAA recommendation *after Zollinger Crack spacing Drying shrinkage Temperature drop Restraints Base friction Curling (thermal and moisture) Steel reinforcement

43. Recycled concrete aggregate (RCA)

44. RCA Can RCA (coarse) provide similar mechanical properties for airfield rigid pavements as virgin aggregates? • Slight strength reduction • Higher shrinkage potential • Lower modulus • Lower concrete density • Potential cost saving ++

45. UIUC First Trial • RCA from Champaign recycling plant • Concrete came from pavements, parking garages, etc. • Mix of materials with unknown properties • Material washed, dried, and sieved to match natural fine aggregate • Soaked for 24 hrs, surface dried, and then 100% replacement of natural fine aggregate

46. Saturated RCA vs Lab Aggregates • Similar autogenous shrinkage curves

47. Mechanical Property Test Plan • Simple lab crusher • Three Point Bend (TPB) test • Fracture properties (Spring 2006) • Full-scale crushing at contractor • Fracture / strength properties • Shrinkage (Summer 2006)

48. Sample Preparation 1. Crush Process

49. Sample Preparation (Con’t) 2. Gradation 3. Mixture Design

50. Sample Preparation (Con’t) P 80 mm 150mm 50 mm CMOD 600mm 700mm 4. Dimensions