Leveling of post tension slabs

[dadoftrips]

I have a post tension slab that was incorrectly installed. I have found that the split wedges use to set the cables after tensioning were of different angles and therefore the tension in the cables were lost or non-existent from the start. The unskilled laborer just pulled out wedges out of a box of assorted wedges. I believe the issues here are QA/QC, lack of good procedures and performing a task that is atypical to the standard field worker.

My question to this forum is whether there is any technique in slab leveling that can take advantage of the post tension technology? Can existing cables be removed and new cables restrung and tensioned to pullup the slab to a uniform level in all directions? My attempt here is to save the need for the installation of piles or piers and save cost of slab leveling.

 

[Focht3]

I think you are out of luck; but perhaps someone else has experience with putting in new cables at a different drape -



Please see FAQ731-376 by [blue]VPL[/blue] for tips on how to make the best use of Eng-Tips Fora.

 

[ishvaaag]

Is this a case where exterior prestress might be of some use?

 

[swthwdy]

Our Structural and Geotechnical Engineers tell us there is no known way to level a PT foundation.
If you are lucky enough to have an Engineer signed and sealed design plan for your PT foundation, you still cannot be assured that the tendons are properly installed in the proper location and depth.
If the framing has been built to the highs and lows of the foundation, forget leveling for sure.
It takes about 5 years for the cracking and separating to be noticed. At least that is our case scenario.
My advice is to hire a Geotechnical Engineer ASAP.
Good luck to you.