Concrete Pavements. How to Get the Biggest Bang for the Buck in Street/Local Road Applications. Brian Killingsworth, PE VP, Pavement Structures NRMCA

Transcription

1 Concrete Pavements How to Get the Biggest Bang for the Buck in Street/Local Road Applications Brian Killingsworth, PE VP, Pavement Structures NRMCA 1 1

2 How to Get the Biggest Bang for the Buck Definitions and Nomenclature Types of Concrete Pavements? Design Optimization Complimentary Design Details Concrete Overlays Concrete Intersections Sustainability 2 2

3 How to Get the Biggest Bang for the Buck Definitions and Nomenclature Types of Concrete Pavements? Design Optimization Complimentary Design Details Concrete Overlays Concrete Intersections Sustainability 3 3

4 Pavement Long-Term Performance = Design + Drainage + Materials + Construction + Maintenance DRAINAGE MATERIALS DESIGN CONSTRUCTION MAINTENANCE 4 4

5 Typical Pavement Types Hot-Mixed Asphalt Concrete (HMAC)/Granular Base HMAC/Granular Base/Stabilized Subgrade Full Depth HMAC Continuously Reinforced Concrete Pavement (CRCP) Jointed Reinforced Concrete Pavement (JRCP) 1 Jointed Plain Concrete Pavement (**JPCP**) HMAC Overlay (Rehabilitation) Unbonded/Bonded Concrete Overlay (Rehabilitation) Note 1: JRCP No Longer Recommended. 5 5

6 Jointed Plain Concrete Pavement 6 6

7 Definitions - Joints Contraction/Sawcut Construction Isolation Longitudinal 8 8

8 Concrete Pavement Design Longitudinal Joint Transverse Joint Surface Texture Surface Smoothness or Rideability THICKNESS DESIGN Concrete Materials Tiebars Dowel Bars (may be optional) Subgrade Subbase 9 9

9 How to Get the Biggest Bang for the Buck Definitions and Nomenclature Types of Concrete Pavements? Design Optimization Complimentary Design Details Concrete Overlays Concrete Intersections Sustainability 10 10

10 Rigid (or Semi-Rigid) Materials Conventional Concrete Full Depth Reclamation With Cement Roller Compacted Concrete Pervious Concrete Fiber Reinforced Concrete Latex Modified Concrete 11 11

11 Rigid Pavement Applications Highways and Interstates Ramps Shoulders Roadways and Streets Overlays Intersections Industrial Applications Parking Lots Bases 12 12

12 Are Concrete Pavements Competitive? YES! When designed equivalent to the other pavement options that are being compared. When detailed appropriately (i.e. optimized)

13 Are Concrete Pavements Competitive? Design Equivalence: Pavement designs using different surface material types or combinations of materials must be designed to be equivalent, i.e. comparable in terms of: Structural Capacity (i.e. Traffic Loading Applications) Reliability (Similar Factors of Safety) Service Life Distress Failure Conditions 14 14

14 Are Concrete Pavements Competitive? Optimized Design Avoid Overdesign by Using Appropriate Method Refine Design Inputs to Match Requirements Evaluate Joint Spacing Maximize Maintenance (Methods & Timing) Develop Multiple Cross-Sections w/various Materials Conduct Multiple Life-Cycle Cost Analyses 15 15

15 How to Get the Biggest Bang for the Buck Definitions and Nomenclature Types of Concrete Pavements? Design Optimization Complimentary Design Details Concrete Overlays Concrete Intersections Sustainability 16 16

16 Optimizing Design for Cost Effectiveness CONCRETE STRUCTURAL DESIGN OPTIMIZATION 17 17

17 Design to Minimize Key Distresses Transverse Cracking Under Slab Erosion Joint Faulting Corner Cracking 18 18

18 Pavement Design Methods 1993 AASHTO Design of Pavement Structures (DARWin) AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG or Pavement ME) ACI R-02: Guide for Design of Jointed Concrete Pavements for Streets and Local Roads American Concrete Pavement Association (ACPA) StreetPave

19 Optimizing Designs Variables which can be optimized for projects: Improved Traffic Estimates (Now & Future) Reliability (What is the Right Factor of Safety?) Concrete Strength (Is Higher Always Better?) Edge Support Conditions (Does Adding Curb Help?) 20 20

20 Optimizing Designs Variables which can be optimized for projects: Subbase (Type, Thickness & Strength, if Needed) Reinforcing Steel (Is It Really Needed?) Load Transfer Condition (Are Dowels Needed?) Joint Sealing (How Necessary Is This?) 21 21

21 When is a Subbase Needed? Subbases Have Little Influence on Required Concrete Pavement Thickness. What Conditions Need to Exist for Subbase Use? Heavy Loading (i.e. Trucks; ADTT > ) Subgrade Susceptible to Pumping/Erosion (fine-grained) Water Available to Subgrade (infiltration or high water table) Risk of Deep Frost Penetration & Heave 22 22

22 When is a Subbase Needed? If Conditions Exists, What Kind of Subbase? Granular (Crushed Stone) Treated (Asphalt or Cement) Recycled (Concrete or Asphalt) Permeable With or Without Drainage System Project Conditions Will Dictate 23 23

23 When is a Subbase Needed? If Conditions Exists, Are There Other Options? Subgrade Stabilization Soil Mixing Subsurface Drainage 24 24

24 Pavements On Expansive Soils Soil Heave Pavement Distress From Expansive Clay Subgrade 25 25

25 Pavements On Expansive Soils Mitigation Techniques Soil Treatment with Cement, Lime, or Fly Ash Geosynthetics: Geotextiles or Geogrids Removal and Replacement of High PI Soils Drains or Barriers to Collect or Inhibit Moisture Infiltration Chemical Injection of Soil Moisture Treatment Soil Mixing 26 26

26 Selecting the Right Treatment Soils and Environment Dependent Presence of Sulfates Material Availability and Cost Local Contractor Experience Project Schedule and Complexity Meet Owner Guidelines 27 27

27 Don t Forget Mitigation Techniques: May Need to be Combined, and May Not Completely Solve the Problem! Treatment of Upper Native Soil Water Native Expansive Soil (High PI) 28 28

28 Is Reinforcing Steel Required? Reinforcing Steel Does Not Contribute to Load Carrying Capacity of Pavement (i.e. Does Not Reduce Required Pavement Thickness). Primarily Used to Keep Cracks Tight. Cause of Pavement Distress Because of Steel Corrosion. Reduce Mid-Slab Cracking By Appropriate Joint Spacing. Thus, No Steel Is Needed! 29 29

29 When Are Dowels Needed? Heavy Truck Traffic Weak Subgrade Conditions Poor Aggregate Interlock If Used: Concrete Thickness > 8 inches Plate Dowels for Thinner Pavements 30 30

30 When Is Joint Sealing Required? Always Should be Considered; However, Will the Joint Sealant be Maintained Over Time? Is There Water or Wind Blown Material Present? Is Subgrade Likely to Pump? Is There Risk of Joints Opening (i.e. Expansive Subgrade)? If These Risks Can be Minimized, Joint Sealing is NOT Necessary

31 Optimizing Design for Cost Effectiveness CONCRETE MIXTURE DESIGN OPTIMIZATION 32 32

32 Supplementary Cementitious Materials Fly Ash Slag Cement Silica Fume 33 33

33 Fly Ash Use in Ready Mixed Concrete ACAA 2008 Survey 72 M Tons Produced 16 M Tons in Cement and Concrete 41 M Tons Landfilled (58%) 2000 PCA Survey >50% of all Ready Mixed Concrete had Fly Ash 15 to 40% Fly Ash is Typical High Volume Fly Ash Mixtures >40% What happens to concrete performance with increased fly ash? 34 34

34 Supplementary Cementitious Materials Properties of Fresh Concrete Type F Fly Ash Type C Slag Cement Silica Fume Water Demand Lower Lower Lower Increase Workability Increase Increase Increase Lower Bleeding and Segregation Lower Lower Inc./Lower Lower Setting Time Increase Inc./Lower Increase No Impact Air Content Lower Lower No Impact Lower Heat of Hydration Lower Inc./Lower Lower No Impact 35 35

35 Supplementary Cementitious Materials Properties of Hardened Concrete Type F Fly Ash Type C Slag Cement Silica Fume Early Age Strength Gain Lower No Impact Inc./Lower Increase Long Term Strength Gain Increase Increase Increase Increase Permeability/Absorption Lower Lower Lower Lower Alkali Silica Reactivity Lower Lower Lower Lower Sulfate Resistance Increase No Impact Increase Increase Freezing and Thawing No Impact No Impact No Impact No Impact 36 36

36 High Volume Fly Ash: Bleeding and Finishing Low w/cm High Volume Fly Ash (HVFA) Concrete: May Have Low Bleeding Possibly Slow Bleed Rate Higher Chance of Plastic Shrinkage Cracking 37 37

37 Cementitious Admixture Interactions Sometimes Very Delayed Setting (> 3 days), Poor Strength Development Possible Mostly in Hot Weather Aluminate-Sulfate Interactions Class C Fly Ash Contributes Aluminates 38 38

38 Concrete Structures Recycled Concrete as Aggregates Concrete Pavements Returned Concrete 39 39

39 Recycled Fine Aggregates Foundry Sands and Slags Crushed Concrete 40 40

40 RCA for Pavements (ACPA 2009)

41 Effects on Fresh Properties 42 42

42 Effects on Hardened Properties 43 43

43 Effect on Durability 44 44

44 Recycled Water Concrete Wash Water (or Greywater) 45 45

45 COMPASS: Mixture Optimization Computer-Based Guidelines (Software Tool) For Job- Specific Optimization of Paving Concrete 46 46

46 COMPASS: Mixture Optimization 48 48

47 How to Get the Biggest Bang for the Buck Definitions and Nomenclature Types of Concrete Pavements? Design Optimization Complimentary Design Details Concrete Overlays Concrete Intersections Sustainability 49 49

48 Complementary Standard Details Standard Details That Should be Addressed: Joints (Contraction, Construction, Expansion) Curbs, Curbs and Gutters Pavement Junction Bus Stop Pad Driveways Inlets/Manholes 50 50

49 How to Get the Biggest Bang for the Buck Definitions and Nomenclature Types of Concrete Pavements? Design Optimization Complimentary Design Details Concrete Overlays Concrete Intersections Sustainability 51 51

50 Why Concrete Overlays? Can be placed on both concrete and asphalt pavements. Offers an economically sound solution with proven extended pavement life. Easy to correct problem areas like poor drainage. Can be Constructed Quickly

51 Thinner Concrete Overlays Thicker Bonded Overlay Family Unbonded Overlay Family Bonded Concrete Overlay of Concrete Pavements Bonded Concrete Overlay of Asphalt Pavements Bonded Concrete Overlay of Composite Pavements Unbonded Concrete Overlay of Concrete Pavements Unbonded Concrete Overlay of Asphalt Pavements Unbonded Concrete Overlay of Composite Pavements Bond is integral to design Old pavement is base 53 53

52 Construction (Concrete Overlay of Existing Asphalt) Place concrete when surface temperature is <120 F. Conventional fixed-form or slip form placement used. Shotblast or mill (if needed) and clean surface thoroughly. Grout or epoxy bonding agents are not required (however local conditions and experience will dictate). Texture Pavement for friction. Curing material must be placed as soon as possible (<30 minutes). Full coverage is essential. Begin sawing as soon as possible (use of early entry saw is recommended). Test mix throughout placement for QC

53 Typical Construction Sequence

54 Paver Screeds 56 56

55 Paver Screeds 57 57

56 How About an Example LOCAL ROAD OVERLAY 58 58

57 Lombard is a suburb due west of Chicago in DuPage County, Illinois Date Source: PCA from the ACI & NRMCA Concrete Solutions Seminar, 9/20/

58 Source: Presented by PCA at the ACI & NRMCA Concrete Solutions Seminar, 9/20/

59 Source: Presented by PCA at the ACI & NRMCA Concrete Solutions Seminar, 9/20/

60 Source: Presented by PCA at the ACI & NRMCA Concrete Solutions Seminar, 9/20/

61 Source: Presented by PCA at the ACI & NRMCA Concrete Solutions Seminar, 9/20/

62 Source: Presented by PCA at the ACI & NRMCA Concrete Solutions Seminar, 9/20/

63 Source: Presented by PCA at the ACI & NRMCA Concrete Solutions Seminar, 9/20/

64 f Joints: 5.5 ft. X 5.5 ft. spacing Source: Presented by PCA at the ACI & NRMCA Concrete Solutions Seminar, 9/20/

65 October 15, 2010 Source: Presented by PCA at the ACI & NRMCA Concrete Solutions Seminar, 9/20/

66 How to Get the Biggest Bang for the Buck Definitions and Nomenclature Types of Concrete Pavements? Design Optimization Complimentary Design Details Concrete Overlays Concrete Intersections Sustainability 68 68

67 Concrete Intersections - Considerations Typically Eliminates Rutting/Cracking Concerns Complete reconstruction or inlay? Concrete intersection construction limits Thickness Design Subgrade and subbase requirements Jointing detail Pavement profiles Concrete materials Concrete to asphalt transitions Traffic detection systems Coordination with local agencies 69 69

68 Concrete Intersections - Timing 70 70

69 Concrete Intersections - Timing 71 71

70 Concrete Intersections - Timing 72 72

71 Concrete Intersections - Timing 73 73

72 Concrete Intersections - Timing 74 74

73 How to Get the Biggest Bang for the Buck Definitions and Nomenclature Types of Concrete Pavements? Design Optimization Complimentary Design Details Life Cycle Cost Analysis Concrete Overlays Sustainability 75 75

74 Concrete Sustainability Concrete streets last longer with less maintenance. Concrete streets reduce Heat Island Effect. Concrete streets are safer at night: lighter color surface reflects more light. Concrete can be used for stormwater management. Concrete is locally produced so you can buy at home and can be recycled at the end of its life

75 The Concrete Sustainability Hub

76 Thank You! Brian Killingsworth, P.E. Vice President, Pavement Structures National Ready Mixed Concrete Association Phone: (830) Mobile: (210)