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

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Presentation on theme: "From… Maintenance Technical Advisory Guide (MTAG) Chapter 8 Full Depth Concrete Repair."— Presentation transcript:

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

2 Learning Objectives 1. List benefits of full-depth repairs 2. Describe primary design considerations 3. List available types of repair materials 4. Describe the recommended construction procedure 5. List important quality control activities 6. Describe potential construction and performance problems 7. Identify troubleshooting solutions

3 I ntroduction D esign considerations C onstruction Q uality control T roubleshooting Presentation Outline

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

5 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) Candidate Distresses

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

9 I ntroduction D esign considerations C onstruction Q uality control T roubleshooting Presentation Outline

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

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

12 Selecting Repair Boundaries Repair 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-HLL LMM No repair required Selecting Repair Boundaries Repair Recommendations (JPCP) d = 1.8 m (6 ft) minimum dd dd d Replace entire slab-outer lane d

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

15 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 Selecting Repair Boundaries Multi-Lane Considerations

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

17 Load Transfer Design Dowel Bars

18 Load Transfer Design Tie Bars

19 PCC mixes Rapid set cement (RSC) Regulated set portland cement (RSPC) Proprietary materials Repair Materials Recommendations

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 Item CodeDescription Construction area signs Traffic control system Portable changeable message sign Remove concrete pavement Repair spalled concrete Repair spalled and unsound surface area Replace concrete pavement (rapid strength concrete Dowel bar retrofit Repair corner breaks Repair spalled joint Replace joint seal (existing concrete pavement) Seal joint (existing concrete pavement) Grind existing concrete pavement Concrete surface finish Concrete surface texture Repair spalled surface area

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

24 I ntroduction D esign considerations C onstruction Q uality control T roubleshooting Presentation Outline

25 1.Concrete sawing 2.Concrete removal 3.Repair area preparation 4.Load transfer provision 5.Material placement 6.Curing 7.Joint sealing Construction Procedure

26 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 Concrete Sawing Considerations

27 Concrete Sawing Example Sawcut

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

29 Concrete Removal Concrete Breakup

30 Concrete Removal Removal with a Backhoe

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

32 Concrete Removal Placement of Lifting Pins

33 Concrete Removal Lifting of Slab Pieces

34 Concrete Removal Disposal of Slab Pieces

35 Repair Area Preparation

36 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 Load Transfer Provision Drilling Recommendations

37 Load Transfer Provision Gang Drill

38 Load Transfer Provision Dowel-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 Provision Cleaning Holes

40 Load Transfer Provision Injecting Grout (or Epoxy)

41 Load Transfer Provision Dowel-Bar Placement

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

43 Load Transfer Provision Area 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 Placement Screeding

47 Material Placement Finishing

48 Material Placement Texturing

49 Curing Application of Curing Compound

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

51 Construction Process Review

52 Special CRCP Considerations

53 CRCP Pavements Candidate Distresses Punchouts (L, M, H) Deteriorated transverse cracks (M, H) Longitudinal cracking (M, H) Blowup (L, M, H) D-cracking (M, H) Deterioration of or near repair (M, H)

54 H H H H M b a b Replace as a single area b a b > 1.8 m a > 1.8 m (6 ft) tied steel b > 46 cm (18 in) a > 1.2 m (4 ft) welded or mechanical connection CRCP Pavements Repair Recommendations

55 1.2 m (4 ft) - welded or 1.8 m (6 ft) tied minimum Full-depth cutPartial-depth cut Failure A Partial-depth cut CRCP Pavements Sawcut Locations A = 200 mm (8 in) minimum – welded; 610 mm (24 in) minimum – tied B = 810 mm (32 in) minimum – welded; 610 mm (24 in) minimum – tied BA

56 CRCP Pavements Restoring Continuity of Reinforcing Steel

57 I ntroduction D esign considerations C onstruction Q uality control T roubleshooting Presentation Outline

58 Similar to conventional PCC paving Verify repair boundaries Monitor to ensure no damage to surrounding concrete Project inspection Proper curing techniques Quality Control

59 Project Checklist Preliminary Responsibilities Document Review Project Review Materials Checks Concrete patch material Load tranfer devices Other materials General

60 Project Checklist Equipment Inspections Concrete Removal Equipment Patch Area Cleaning Equipment Testing Equipment Placing and Finishing Equipment Others Weather Requirements Traffic Control

61 Project Checklist Project Inspection Responsibilities Concrete removal and cleanup Patch preparation Placing, finishing, and curing concrete Resealing joints and cracks Cleanup Responsibilities

62 I ntroduction D esign considerations C onstruction Q uality control T roubleshooting Presentation Outline

63 Troubleshooting Construction and performance problems Approach: Identify Problem Determine Cause Identify Solution

64 What is wrong here?

65 Selecting Repair Boundaries What is wrong here?

66

67

68 Problem: Longitudinal cracking in the patch Potential causes? Troubleshooting Possible Performance Problems

69 Problem: Transverse cracking in the patch Potential causes? Troubleshooting Possible Performance Problems

70 Problem: Surface scaling Potential causes? Troubleshooting Possible Performance Problems

71 Problem: Spalling in patch at the transverse or longitudinal joint Potential causes? Troubleshooting Possible Performance Problems

72 Problem: Deterioration adjacent to the patch Potential causes? Troubleshooting Possible Performance Problems

73 Problem: Settlement of the patch Potential causes? Troubleshooting Possible Performance Problems

74 Troubleshooting Guide – Causes and Solutions Undercut spalling Saw binds Adjacent slab damage Slab disintegration Patch filled with water Grout flow out of dowel holes Misaligned dowels

75 Introduction Design considerations Construction Quality control Troubleshooting Presentation Outline

76 Learning Objectives 1. List benefits of full-depth repairs 2. Describe the primary full-depth repair design considerations 3. List available types of repair materials 4. Describe the recommended construction procedure 5. List important quality control activities 6. Describe potential construction and performance problems 7. Identify troubleshooting solutions


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