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Chapter 8 Full Depth Concrete Repair

Chapter 8 Full Depth Concrete Repair. From… Maintenance Technical Advisory Guide (MTAG). Learning Objectives. List benefits of full-depth repairs Describe primary design considerations List available types of repair materials Describe the recommended construction procedure

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Chapter 8 Full Depth Concrete Repair

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  1. Chapter 8Full Depth Concrete Repair From… Maintenance Technical Advisory Guide (MTAG)

  2. Learning Objectives • List benefits of full-depth repairs • Describe primary design considerations • List available types of repair materials • Describe the recommended construction procedure • List important quality control activities • Describe potential construction and performance problems • Identify troubleshooting solutions

  3. Presentation Outline • Introduction • Design considerations • Construction • Quality control • Troubleshooting

  4. Introduction • Definition Cast-in-place concrete repairs that extend the full-depth of the existing slab • Purpose • Repair localized distress • Preparation for an overlay

  5. Candidate Distresses • Transverse cracking (M, H) • Longitudinal cracking (M, H) • Corner breaks (L, M, H) • Spalling (M, H) • Blowup (L, M, H) • D-cracking (M, H) • Deterioration of existing repairs (M, H)

  6. Benefits • Restored rideability • Restored structural integrity • Prevents further deterioration

  7. Limitations • Does not address structural inadequacy • Not a long-term solution for material-related distresses • Widespread deterioration • Cost considerations

  8. Module 8-1 Design, Materials & Specifications From… Maintenance Technical Advisory Guide (MTAG)

  9. Presentation Outline  • Introduction • Design considerations • Construction • Quality control • Troubleshooting

  10. Design Considerations • Selecting repair boundaries • Load transfer design • Selection of repair materials • Curing • Opening to traffic

  11. Selecting Repair BoundariesExtent of Deterioration at Joint Visual deterioration of surface Existing Joint Dowel bar Actual deterioration at bottom of slab

  12. Selecting Repair BoundariesRepair Dimensions • Minimum dimensions • Use lane-width repairs • Length > 1.8 m (6 ft) • Long repairs (>3.7 m [12 ft] long) • Provide reinforcement, or • Provide intermediate doweled joint

  13. Some typical distress conditions noted with L = low M = medium H = high M-H L L M-H L M M d d d d d d No repair required Replace entire slab-outer lane d = 1.8 m (6 ft) minimum Selecting Repair BoundariesRepair Recommendations (JPCP)

  14. L L L H L L L L L L L L M L L M L L H L M-H L L H M Some typical distress conditions noted with L = low M = medium H = high d d d d Replace entire slab-outer lane d d d = 1.8 m (6 ft) minimum Selecting Repair BoundariesRepair Recommendations (JRCP) No repair required

  15. Selecting Repair BoundariesMulti-Lane Considerations • Adjacent lanes can be repaired independently • Matching joints is not essential • Avoid small offsets • If blowups in adjacent lane • Delay until cooler weather • Cut pressure relief joints

  16. Load Transfer DesignRecommendations Traffic Direction Mid-depth slab Smooth dowels or deformed rebars Smooth dowels 38 mm (1.5 in) dia. 0.6 m (2 ft) 3.7 m (12 ft) 0.3 m (1 ft) typical 1.8 m (6 ft) minimum

  17. Load Transfer DesignDowel Bars

  18. Load Transfer DesignTie Bars

  19. Repair MaterialsRecommendations • PCC mixes • Rapid set cement (RSC) • Regulated set portland cement (RSPC) • Proprietary materials

  20. Curing • Curing compound • Insulation blankets • HIPERPAV software

  21. Opening to Traffic • Opening criteria • Minimum strength • Minimum time • Typical strength • 13.8 MPa (2,000 psi) compressive • 2.1 MPa (300 psi) center-point • 1.7 MPa (250 psi) third-point

  22. Typical Item Codes http://i80.dot.ca.gov/hq/esc/oe/awards/#item_code

  23. Module 8-2 Construction and Inspection From… Maintenance Technical Advisory Guide (MTAG)

  24. Presentation Outline  • Introduction • Design considerations • Construction • Quality control • Troubleshooting 

  25. Construction Procedure • Concrete sawing • Concrete removal • Repair area preparation • Load transfer provision • Material placement • Curing • Joint sealing

  26. Concrete SawingConsiderations • Full-depth, diamond-bladed sawing • Pressure relief cuts on hot days • Limit traffic loading on sawed pavement to avoid pumping • If asphalt shoulder present, remove 150 mm (6 in) for form space

  27. Concrete SawingExample Sawcut

  28. Concrete RemovalBreakup and Cleanout Method • Advantages • Efficient breakup of concrete • Rapid removal of concrete onto trucks • Disadvantages • Greatly disturbs subbase • Potential to damage slab

  29. Concrete RemovalConcrete Breakup

  30. Concrete RemovalRemoval with a Backhoe

  31. Concrete RemovalLiftout Method • Advantages • Does not disturb subbase • More rapid material removal • Disadvantages • Disposal of large concrete pieces • Process requires lifting pins and heavy lifting equipment

  32. Concrete RemovalPlacement of Lifting Pins

  33. Concrete RemovalLifting of Slab Pieces

  34. Concrete RemovalDisposal of Slab Pieces

  35. Repair Area Preparation

  36. Load Transfer ProvisionDrilling Recommendations • Dowel holes drilled on 305 mm (12 in) centers at mid-depth • Dowel holes drilled slightly larger than dowel diameter • Smooth steel dowel bars or deformed tie bars can be used

  37. Load Transfer ProvisionGang Drill

  38. Load Transfer ProvisionDowel-Bar Placement • Blow debris and dust from holes • Place grout or epoxy in holes • Insert dowel into hole with slight twisting motion • Install grout retention disks • Grease protruding dowel ends

  39. Load Transfer ProvisionCleaning Holes

  40. Load Transfer ProvisionInjecting Grout (or Epoxy)

  41. Load Transfer ProvisionDowel-Bar Placement

  42. Load Transfer ProvisionDowel-Bar Placement Existing slab Grout-retention disk (optional) Anchoring material Hole dia. = d+a Repair area d = dowel diameter a = 2 mm (1/8 in) for epoxy Subbase a = 6 mm (1/4 in) for cement grout Subgrade Soil

  43. Load Transfer ProvisionArea Prepared with Dowels in Place

  44. Material Placement • Consolidation and level finish are critical • Vibrate along edges of repair • Avoid addition of extra water • Texture surface to match existing pavement

  45. Material Placement

  46. Material PlacementScreeding

  47. Material PlacementFinishing

  48. Material PlacementTexturing

  49. CuringApplication of Curing Compound

  50. Joint Sealing • Saw and seal as soon as possible after placement • Follow the procedures described in Module 3-1

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