Maximum Pour size for PT slab?

[PSR_1]

Hello everyone! A simple question abound the maximum allowed pour area for post tensioned slab and what maximum length is allowed for PT slabs without pour strip.

 

[ooox]

The maximum pour size is determined by site logistics how many concrete trucks the contractor can get to site before they need to stop. The maximum I've experienced is 1200m3 in a day

For tendon lengths, about 30m for a band beam, 40m for a slab tendon. If you use double live end tendons you can go about double that, but pour sizes may become impractical. Minimum tendon length of about 6m, otherwise losses from wedge draw in become excessive.

 

[rapt]

999's numbers on tendon lengths would be for unbonded tendons. We would normally recommend about 25% less for bonded tendons due to the higher friction.

At 80m slab length you would need to look closely at shortening effects on columns near the edges and restraint effects on the slab.

RE maximum volume of pour, the pour size is also controlled by the surface area that needs to be finished. That would depend on local building practice.

 

[ooox]

RAPT,

I know I'm based on the US where unbonded tendons is common practice, however, based on the OP's previous posts I assumed he was referring to bonded tendons and so the maximum tendons length I provided were based on PTIA's 'Practical Pretress Detailing' - are you recommending the values in this document should reduced by 25%?

999

 

[rapt]

Yes, 40m single end stress and 80m double end stress is not recommended.