how to fix post tension if one of the cables is partially exposed at the top? 1

[delagina]

a post tension slab on grade for a house foundation, you can visually see one of the cables partially. how do you fix this?

 

[hokie66]

Already stressed? Bonded or unbonded? Is this just one strand or several strands in a tendon? Is the post-tensioning supposed to be level or draped? How much prestress over the gross area of the slab?

 

[delagina]

already stressed, unbonded, just one strand.. not sure if level or draped.. dont know how much pre stress.. i was just asked this question.. i have not designed any PT slab

 

[hokie66]

I suppose you could destress it, chip out enough concrete to lower the strand into position, patch around it, and restress. Or maybe just destress and remove or abandon this strand. I don't have much faith in unbonded strands in slabs on grade. If a crack forms, the slab can just slide along toward the anchored ends.

 

[delagina]

If it's bonded, how do you fix it?

 

[dik]

paint it gray to match the concrete <G>.

If wear and tear will damage the sheathing, then a bonded topping in the vicinity. If not needed for fire rating, then likely just leave it... local stresses may be higher due to greater eccentricity.

Dik

 

[hokie66]

If bonded and it projects above the slab, you could cut out the offending part and patch.

 

[delagina]

you mean cut off the pt rebar?

 

[strguy11]

If it is unbonded, there is a connection typically referred to as a "dogbone" type of connection. These are used alot in parking garage type repairs. You could use 2 of these (one on each end) and splice in a new piece of strand and restress it. These however, do take up a lot of room, so cover could be an issue for you.

If bonded, check the development of the strand. After a certain point, the tendon should regain its full capacity since it is bonded to the concrete. Do you need it for strength or just crack control? Check with VSL. They are good about helping with different type of repairs. Not sure what you would do in your case, but I would think you would need to use some sort of external anchor and a post tensioning rod. You might be able to chip away some of the concrete and embed this in the slab, and "splice" across the damaged areas, but this could be tricky. Again, check with VSL or another PT supplier.

 

[hokie66]

Yes, I meant to just cut out the offending strand. After all, it is just a slab on grade.