423.4R-98
Corrosion and Repair of Unbonded Single Strand Tendons
1998, 20 pp.
$31.50

This report gives general information regarding the evaluation corrosion damage in structures reinforced with unbonded single strand post-tensioning tendons. Historical development of those parts of the building code dealing with durability and corrosion protection is explained. Evolution of the types and components of unbonded tendons is described. Specific aspects of corrosion in unbonded single strand tendons are described, and common problems in structures reinforced with these tendons are discussed. Methods are presented for repairing, replacing, and supplementing tendons.

Contents:
Chapter 1 - Introduction

1.1 General

1.2 Background

1.3 SCope

1.4 Limitations

Chapter 2 - Review of Code Requirements

2.1 General

2.2 Cover requirements for unbonded tendons

2.3 Allowable tensile stresses in concrete

2.4 Protection of unbonded tendons

Chapter 3 - Unbonded Tendons

3.1 Evolution of unbonded tendons

3.2 Sheathing problems

3.3 Detailing practices

3.4 Storage, handling & construction problems

3.5 Deterioration mechanisms

3.6 Performance record

Chapter 4 - Evaluating Corrosion Damage

4.1 Gee\neral

4.2 Condition surveys of concrete

4.3 Condition surveys of tendons

4.4 Nondestructive testing

4.5 Exploratory concrete removal

4.6 Exposing tendons

4.7 Strand removal

4.8 Other testing & investigative procedures

Chapter 5 - Repair Schemes & Methods

5.1 General

5.2 Existing tendon repair

5.3 Strand replacement

5.4 Tendon replacement

5.5 External post-tensioning

5.6 Continuous acoustic monitoring

5.7 External non-prestressed reinforcement or support

5.8 Total demolition & replacement

Chapter 6 - Summary

Chapter 7 - References