Post-Tensioning Tendon Installation and Grouting Manual

Overall Contents

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1.1 Objective

1.1.1 Benefits of Post-Tensioning
1.1.2 Principle of Prestressing
1.1.3 Post-Tensioning Operations
1.1.4 Post-Tensioning Systems

1.2 Permanent Post-Tensioned Applications

1.2.1 Cast-in-Place Bridges on Falsework
1.2.2 Post-Tensioned AASHTO, Bulb-T, and Spliced Girders
1.2.3 Cast-in-Place Segmental Cantilever Bridges
1.2.4 Precast Segmental Balanced Cantilever Bridges

1.2.4.1 Typical Features of Precast Cantilever Segments
1.2.4.2 Cantilever Tendons
1.2.4.3 Continuity Tendons

1.2.5 Precast Segmental Span-by-Span Bridges
1.2.6 Transverse Post-Tensioning of Superstructures
1.2.7 Post-Tensioning of Substructures

1.2.7.1 Hammerhead Piers
1.2.7.2 Straddle Bents
1.2.7.3 Cantilever Piers
1.2.7.4 Precast Piers
1.2.7.5 Precast Segmental Box Section Arches
1.2.7.6 Transverse, Confinement Tendons at Tops of Piers

1.3 Temporary Longitudinal Post-Tensioning (Bars) - Typical Applications

1.3.1 Erection of Precast Cantilever Segments
1.3.2 Closure of Epoxy Joints in Span-by-Span Erection

2.1 Prestressing Steel

2.1.1 Strands and Bars

2.1.1.1 Strands
2.1.1.2 Bars

2.1.2 Shipping, Handling and Storage
2.1.3 Acceptance

2.2 Grout

2.2.1 Purpose
2.2.2 Cement and other Pozzolans for Grout
2.2.3 Pre-bagged Grouts
2.2.4 Thixotropic vs. Non-Thixotropic Grouts
2.2.5 Admixtures
2.2.6 Laboratory Tests

2.2.6.1 Setting Time
2.2.6.2 Grout Strength
2.2.6.3 Permeability
2.2.6.4 Volume Change
2.2.6.5 Pumpability and Fluidity (Flow Cone)
2.2.6.6 Simulated Field High Temperature Fluidity Test
2.2.6.7 Bleed
2.2.6.8 Corrosion
2.2.6.9 Wet Density

2.2.7 Shipping, Handling, Storage and Shelf life
2.2.8 Acceptance
2.2.9 Field Mock-Up Tests

2.3 Ducts

2.3.1 Duct Size

2.3.1.1 Strand Tendons
2.3.1.2 Bar Tendons

2.3.2 Ducts for Tendons

2.3.2.1 Corrugated Steel
2.3.2.2 Smooth, Rigid Steel Pipe
2.3.2.3 Corrugated Plastic
2.3.2.4 Smooth, High Density Polyethylene Pipe (HDPE) for External Tendons
2.3.2.5 Plastic Fittings and Connections for Internal Tendons
2.3.2.6 External Tendon Duct Connections
2.3.2.7 Shrink Sleeves

2.3.3 Shipping, Handling and Storage of Ducts
2.3.4 Acceptance of Duct Materials

2.4 Other Post-Tensioning System Hardware

2.4.1 Anchorages

2.4.1.1 Basic Bearing Plates
2.4.1.2 Special Bearing Plates or Anchorage Devices
2.4.1.3 Wedge Plates
2.4.1.4 Wedges and Strand-Wedge Connection

2.4.2 PT Bars, Anchor Nuts and Couplers
2.4.3 Grout Inlets, Outlets, Valves and Plugs
2.4.4 Permanent Grout Caps

2.5 Other PT System Qualification Tests

3.1 Shop Drawings

3.1.1 Drawings and Details

3.1.1.1 Purpose
3.1.1.2 Typical Contents
3.1.1.3 Typical Approval Process

3.1.2 Stressing Calculations

3.1.2.1 Example 1: Four Span Spliced I - Girder
3.1.2.2 Example 2: External Tendon in End Span

3.2 Tendon Testing On Site

3.2.1 Friction
3.2.2 Modulus of Elasticity

3.3 Anchorages and Anchor Components

3.3.1 Standard or Basic Anchor Bearing Plate
3.3.2 Multi-Plane Anchor
3.3.3 Special (Composite) Anchor Plates
3.3.4 Anchor Plates for Bar Tendons
3.3.5 Local Zone Reinforcement

3.4 Duct Installation

3.4.1 Alignment

3.4.1.1 Ducts for Internal Tendons: I-girders and Cast-in-Place Construction
3.4.1.2 Ducts for Internal Tendons in Precast Segments
3.4.1.3 Ducts for External Tendons in Cast-in-Place and Precast Segments
3.4.1.4 Alignment at Anchors
3.4.1.5 Cover

3.4.2 Duct Supports
3.4.3 Splices and Connections
3.4.4 Grout Inlets and Outlets
3.4.5 Size of Pipes for Grout Inlets, Outlets and Drains
3.4.6 Positive Shut-Offs
3.4.7 Protection of Ducts during Concrete Placement

3.4.7.1 Concrete Pressure
3.4.7.2 Movement of Concrete
3.4.7.3 Vibration of Concrete

3.5 Tendon Installation

3.5.1 Tendon Types
3.5.2 Proving of Internal Post-Tensioning Ducts
3.5.3 Installation Methods
3.5.4 Aggressive Environments
3.5.5 Time to Grouting and Temporary Tendon Protection

3.6 Jacks and Other Stressing Equipment

3.6.1 Types

3.6.1.1 Mono-Strand Jacks
3.6.1.2 Multi-Strand Jacks
3.6.1.3 Bar Jacks

3.6.2 Calibration

3.6.2.1 Jack and Gauge
3.6.2.2 Master Gauge
3.6.2.3 Calibration Curve
3.6.2.4 Jack Repair

3.7 Jacking Methods

3.7.1 Single (Mono) Strand Stressing

3.7.1.1 Single Strand, Single End and Alternate End Stressing
3.7.1.2 Single Strand, Two-End Stressing

3.7.2 Multi-Strand

3.7.2.1 Multi-Strand, Single End Stressing and Alternate End Stressing
3.7.2.2 Multi-Strand, Two-End Stressing

3.7.3 Bar Tendons

3.8 Stressing Operations

3.8.1 Personnel and Safety
3.8.2 Jacking Force
3.8.3 Measuring Elongations on Strand Tendons
3.8.4 Measuring Elongations on PT Bars
3.8.5 Field Variables

3.8.5.1 Friction
3.8.5.2 Anchor Set or Wedge Set
3.8.5.3 Strand Slip
3.8.5.4 Re-Gripping of Strand by Wedges

3.8.6 Final Force
3.8.7 Strand End Cut-Off
3.8.8 Lift-Off

3.9 Stressing Records
3.10 Stressing Problems and Solutions

3.10.1 Strand Slip
3.10.2 Wire Breaks
3.10.3 Elongation Problems

3.10.3.1 Too Small Elongation at Jacking End under Full Load
3.10.3.2 Low Elongation for Whole Tendon
3.10.3.3 Elongation Greater than Tolerance
3.10.3.4 Low Stressing Force
3.10.3.5 Overall Tolerance on a Group of Tendons

3.10.4 Breaking Wedges

4.1 Grouting Plan
4.2 Grout Testing
4.3 Grouting Operations

4.3.1 Verification of Post-Tensioning Duct System Prior to Grouting

4.3.1.1 Check for Water and Debris
4.3.1.2 Proving Ducts with Torpedo
4.3.1.3 Inlets, Outlets and Connections
4.3.1.4 Pressure Check of Duct System

4.3.2 Grouting Equipment

4.3.2.1 Mixer, Storage Hopper, Screen, Pump, Pressure Gauges, Hoses
4.3.2.2 On-Site Test Equipment for Production Grouting
4.3.2.3 Vacuum Grouting Equipment
4.3.2.4 Stand-by Grouting Equipment
4.3.2.5 Clean Grouting Equipment

4.3.3 Batching and Mixing
4.3.4 On-site Tests for Production Grouting

4.3.4.1 Production Bleed Test-Prior to Injection
4.3.4.2 Normal, Non-Thixotropic, Grout-Prior to Injection at Inlet
4.3.4.3 Thixotropic Grout-Prior to Injection at Inlet
4.3.4.4 Normal, Non-Thixotropic Grout-Discharge at Final Outlet
4.3.4.5 Thixotropic Grout-Discharge at Final Outlet

4.3.5 Injection of Grout

4.3.5.1 Pumping
4.3.5.2 Limiting Grout Injection Pressures
4.3.5.3 Grout Flow Rate

4.3.6 Grout Injection of Superstructure Tendons

4.3.6.1 Locations of Inlets and Outlets
4.3.6.2 Sequence of Using and Closing Outlets
4.3.6.3 Grout Pressure Test for Leaks
4.3.6.4 Release Entrapped Air and Lock-Off
4.3.6.5 Incomplete Grouting

4.3.7 Grout Injection of Vertical Tendons

4.3.7.1 Grout Material
4.3.7.2 Standpipes
4.3.7.3 Grout Injection
4.3.7.4 Incomplete Grouting

4.3.8 Post-Grouting Inspection

4.3.8.1 Opening Inlets and Outlets for Inspection
4.3.8.2 Drill Grout to Verify Absence of Voids
4.3.8.3 Frequency of Inspection
4.3.8.4 Filling Drilled Inspection Holes
4.3.8.5 Incomplete Grouting

4.3.9 Filling Voids by Vacuum Grouting

4.3.9.1 Time for Completion of Vacuum Grouting
4.3.9.2 Grout Material
4.3.9.3 Equipment
4.3.9.4 Vacuum Grouting Operation

4.3.10 Sealing of Grout Inlets and Outlets
4.3.11 Protection of Post-Tensioning Anchorages
4.3.12 Grouting Report

4.4 Grouting Problems and Solutions

4.4.1 Interruption of Grout Flow
4.4.2 Too High Grouting Pressure
4.4.3 Flushing of Incomplete Grout
4.4.4 Unanticipated Cross-Grouting
4.4.5 Production Grout Fluidity Unacceptable

4.5 Examples of Grouting Procedures

4.5.1 Example 1: Two-Span Spliced I-Girder
4.5.2 Example 2: Four-Span Spliced I-Girder
4.5.3 Example 3: Cantilever and Drop-In Spliced 3-Span I-Girder
4.5.4 Example 4: Cast-in-Place on Falsework
4.5.5 Example 5: Cantilever or Top Continuity Post-Tensioning
4.5.6 Example 6: Bottom Continuity Tendon in Variable Depth Cantilever
4.5.7 Example 7: End Span External Tendon in Span-by-Span Structure
4.5.8 Example 8: Inlet and Outlet Connections to Bottom External Tension
4.5.9 Example 9: Lateral Tendons in Hammerhead Pier Cap
4.5.10 Example 10: Vertical Post-Tensioning in Pier
4.5.11 Example 11: Cantilever C-Pier

A.1 Post-Tensioning Systems
A.2 Post-Tensioning Grout Related Definitions
A.3 Contract Administration Definitions
A.4 Abbreviations and Acronyms

B.1 Contractor's Personnel

B.1.1 Project Engineer
B.1.2 Project Superintendent / Manager
B.1.3 Foreman
B.1.4 Crews for Tendon Installation and Stressing
B.1.5 Crews for Tendon Grouting

B.2 Construction Engineering and Inspection (CEI)

B.2.1 Resident Engineer or Senior Project Engineer
B.2.2 Project Engineer
B.2.3 Lead Inspector
B.2.4 Inspector

C.1 Cantilever Tendons
C.2 Continuity Tendons
C.3 Continuity Tendons in Expansion Joint Spans
C.4 In-Span Hinges in Balanced Cantilever Construction
C.5 Precast Segmental Span-by-Span Bridges
C.6 Precast Segmental Progressive Cantilever Bridges
C.7 Transverse Post-Tensioning

C.7.1 Transverse Top Slab Post-Tensioning
C.7.2 Transverse Post-Tensioning of Multiple Precast Element Superstructures
C.7.3 Transverse Post-Tensioning in Diaphragms
C.7.4 Vertical Post-Tensioning in Diaphragms
C.7.5 Transverse Post-Tensioning in Deviator Ribs of Precast Segments
C.7.6 Vertical Post-Tensioning Bars in Webs

D.1 Corrosion Protection

D.1.1 Background
D.1.2 Levels of Protection

D.2 Corrosion Protection Materials

D.2.1 Concrete Cover
D.2.2 Ducts
D.2.3 Grout
D.2.4 Other Considerations

D.3 Corrosion Protection along a Tendon

D.3.1 Internal Tendons
D.3.2 External Tendons

D.4 Sealing Intermediate Inlets and Outlets

D.4.1 Internal Tendons
D.4.2 External Tendons

D.5 Corrosion Protection at Anchorages

D.5.1 Possible Levels of Anchorage Protection
D.5.2 Permanent Grout Caps
D.5.3 Anchor Protection Details
D.5.4 Post-Tensioning Anchorage Protection Installation

D.5.4.1 Surface Preparation
D.5.4.2 Forms for Anchorage Pour-Backs
D.5.4.3 Seal Coatings - On Non-Visible Surfaces
D.5.4.4 Concrete Test Block for Seal Coating on Visible Vertical Surfaces

D.6 Temporary Protection during Construction
D.7 Watertight Segmental Box Girder Bridges