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Concrete Mixture Designs for O’Hare Modernization Plan

Concrete Mixture Designs for O’Hare Modernization Plan. University of Illinois (Urbana-Champaign) Department of Civil and Environmental Engineering. Chicago O’Hare January 12, 2006. Project Goal.

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Concrete Mixture Designs for O’Hare Modernization Plan

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  1. Concrete Mixture Designs for O’Hare Modernization Plan University of Illinois (Urbana-Champaign) Department of Civil and Environmental Engineering Chicago O’Hare January 12, 2006

  2. Project Goal Investigate cost-effective concrete properties and pavement design features required to achieve long-term rigid pavement performance at Chicago O’Hare International.

  3. Project Team Principal Investigators • Prof. Jeff Roesler • Prof. David Lange Students • Cristian Gaedicke • Sal Villalobos • Zach Grasley • Rob Rodden

  4. 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

  5. Project Objectives Material constituents and mix design Analysis of existing concrete mix designs Long-term perfor-mance at ORD Laboratory tests Concrete properties Modeling Test for material properties Optimal joint types and spacing.

  6. FY2005 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

  7. TN2: PCC Mix Design

  8. Survey of Existing Mixes

  9. Tech Note 3 • Fiber Reinforced Concrete for Airfield Rigid Pavements • Final cost: reduction of 6% to an increase of 11%

  10. Tech Note 4 • Feasibility of Shrinkage Reducing Admixtures for Concrete Runway Pavements • Reduced Shrinkage and Cracking Potential ~ 50% reduction • Cost limitations (?) Figure 1. Unrestrained shrinkage of mortar bars, w/c = 0.5 (Brooks et al. 2000)

  11. Tech Note 11 • Measurement of Water Content in Fresh Concrete Using the Microwave Method • Strengths: quick, simple, and inexpensive • Limitations: need accurate information on • cement content • aggregate moisture and absorption capacity

  12. TN 12: Guiding Principles for the Optimization of the OMP PCC Mix Design • 1st order: • Strength, workability • 2nd Order: • Shrinkage, fracture properties • LTE & strength gain

  13. Tech Note 15 • Evaluation, testing and comparison between crushed manufactured sand and natural sand • Gradation • physical properties

  14. Manufactured vs Natural Sand 4mm 500mm 4mm 500mm • Visual evaluation • Material retained in the #8 sieve shows difference in the particle shape • The Manufactured sand shows a rough surface and sharp edges due to the crushing action to which it was subjected. Sieve No. 8 Sieve No. 50

  15. Tech Note 16 • Concrete Mix Design Specification Evaluation • Preliminary P-501 evaluation • Strength, shrinkage, and material constituent contents

  16. 2005 Accomplishments • Specification Assistance • On-site meetings at OMP headquarters • Brown bag seminars • Continued specification assistance (2006): • Material constituents (aggregate type and size, SCM, etc.) • Modulus of rupture and fracture properties of concrete • Shrinkage (cement content, w/c ratio limits,etc.) • Saw-cut timing, spacing and depth • Pavement design

  17. PCC Mix Evaluation – Phase II • Effect of aggregate size (0.75” 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 cleaniness

  18. PCC Mix Evaluation – Phase II • Testing • Fresh concrete properties • Slump, Air Content, Unit Weight • Mechanical Testing • Compressive strength (fc) at 7 and 28 days • Modulus of Elasticity (E) at 7 and 28 days • Split tensile strength (fsp) at 7 and 28 days • Modulus of Rupture (MOR) at 7 and 28 days • Volume Stability Testing • Drying and Autogenous Shrinkage trends for 28+ days • Fracture tests • Early-ages (<48 hrs) • Mature age (28 days)

  19. Mixture design nomenclature 9 mixes were prepared: 555.44 – 555.44 st – 688.38 – 688.38 st AAA.BB ** **max aggregate size st = 0.75” Otherwise 1.5” Cementitious content (17%FA) lbs/cy w/cm

  20. Phase II Mix Design Results

  21. Strength Summary

  22. Shrinkage Results Phase II • Total and Autogenous shrinkage

  23. Drying Shrinkage – Phase II

  24. Fracture Energy – Phase II Peak Load GF = Area under the Curve Cracking Area • GF = cracking resistance of material • GF = joint surface roughness indicator

  25. WST Test The WST Specimen 80mm 40mm 80mm Notch detail 30mm 200 mm 57mm b t 2mm a 205mm 200 mm a = a/b

  26. Testing Plan – 4 Mixtures Wedge splitting specimens (7) 6, 8, 10, 12 and 24 hours 7 and 28 days Cylinders for compression and split tensile strength for 1,7 and 28 days and E values for 7 and 28 days MOR for 28 days

  27. Fracture Plots of PCC mixtures

  28. Fracture Energy Results-Phase II • Age = 28-days

  29. Concrete Brittleness • Characteristic Length Less brittle mixes w/ larger MSA

  30. GF vs Joint Performance Chupanit & Roesler (2005) Fracture Energy  Shear Stiffness  Joint Performance *need crack width!

  31. PCC Mix Design – Phase II • Summary* • Larger aggregates reduce strength by 20% • 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 • TNXX – February 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.

  32. Saw-cut timing and depth • Stress analysis of slab (temp & shrink) • Size Effect (fracture) Model • Concrete Material Fracture Parameters • Wedge Splitting Test @ early ages • No method to obtain Critical Stress Intensity Factor (KIC) and Critical Crack Tip Opening Displacement (CTOCC) for WST FEM MODEL FOR THE WST SPECIMEN

  33. Saw-cut timing and depth 80mm 40mm 80mm 30mm 200 mm 57mm 2mm 205mm 200 mm • Fracture Parameters • WST specimen Notch detail b t a a = a/b

  34. Saw-cut timing and depth • FEM Model • Special Mesh around crack tip • Q8 elements • Symmetry and BC consi-derations 200 mm 100 mm

  35. Saw-cut timing and depth Quarter point nodes • FEM Model • Stress around crack tip • Calculation of KI

  36. FEM ANALISYS FEM MODELING OF THE WST Psmax = peak splitting load KIC = critical SIF CTODc= critical CTOD CMODc= critical CMOD f1(a) = geometrical factor 1 f2(a) = geometrical factor 2 f3(a) = geometrical factor 3 E = modulus of elasticity Gf = initial fracture energy

  37. Evolution of GF vs Age 1.5” max aggregate size Large increase in GF between 8 and 24 hrs (saw-cutting operations).

  38. Saw-Cut Timing Model • Concrete E and fracture properties(cf ,KIC)at early ages. • Using Bazant’s Size Effect Model to analyze finite size slabs. • Develop curves of nominal strength vs notch depth for timing. • After Soares (1997)

  39. Joint Type Analysis How can we rationally 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

  40. Reduced aggregate interlock with small max. size CA Dowels deemed necessary Crack width, w

  41. Larger max. size CA Larger aggregate top size increases aggregate interlock and improves load transfer Crack width, w

  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 DG2002 Crack spacing Drying shrinkage Temperature drop Restraints Base friction Curling (thermal and moisture) Steel reinforcement

  43. Step 1: Predicting crack width opening, w Average increase with age due to shrinkage

  44. Future Joint Analysis Questions • What is an acceptable LTE? • What is LTE when dowels are removed? • Can joint spacing be increase from 18.75 to 25 ft? • How much can LTE be changed by concrete property changes?

  45. Project Tasks and Progress Status Done, TN2, 3, 4, 15 • Literature Review • Survey of existing mix designs • Review of mix design strategies • Volume Stability Tests • Drying and Autogenous shrinkage • Optimization of concrete mixes to reduce volumetric changes • Strength Testing • Modulus of rupture, splitting and compressive strength • Fracture energy and fracture surface roughness Done, TN 12 Done Done, TN 12 and TN 17. Done, TN 12, TN 17, conf. paper Fracture Tests Done

  46. Project Tasks and Progress In progress, TN 3. Analysis pending, fracture and shrinkage tests done. • Joint Type Design • Slab size and jointing plans: productivity, cost, performance. • Optimization of concrete aggregate interlock to ensure shear transfer. • Joint (crack) width prediction model for concrete materials. In progress, TN 12. Fracture tests In progress

  47. Project Tasks and Progress FEM model developed to obtain fracture results from WST samples, currently applying results to determine saw-cut timing and depth. • Saw-cut timing and depth • Saw-cut timing criteria for the expected materials • Analytical model / Validation • Fiber Reinforced Concrete Materials • Overview of structural fibers for rigid pavement Literature Review done, TN 3.

  48. New Work for FY2006 • Functionally-layered concrete pavements • Multi-functional rigid pavement • Cost saving • GREEN-CRETE • Recycled concrete aggregate • Effect of recycled aggregate on mechanical and volumetric properties of concrete

  49. Current work:Recycled Concrete as Aggregates (RCA) for new Concrete

  50. Recycled Concrete Aggregate

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