Broken Strand Coupling and Retentioning

The Problem

A cold joint between a slab on grade and post tensioned structural slab was not properly maintained. Water penetrated the caulking at this joint. The water got into the strand sheathing at the strand anchorage causing strand corrosion. Several strands were broken completely.

The Solution

The slab on grade was removed to expose the live end anchorage. Where possible, lift-off testing was completed to find broken or reduced capacity strands. Other strands were exposed and tested with a screw driver for tension. Broken strands were extracted. New strand was threaded into existing sheathing. A coupler was inserted and the strands were re-tensioned per engineering instructions.
Strands with reduced capacity were de-tensioned. Area's of significant corrosion were cut and spliced. Re-tensioning type couplers were used for the repair.

Project Images

Picture of anchorage corrosion and installed pigtails for lift-off testing

Re-tensioning strand with coupler and torque wrench

View of joint between slab on grade and structural slab. Notice small portion of S.O.G. is removed

Extracted strand was broken due to corrosion of wires