Fill pit with concrete

[ben3929]

I am working on a project to fill several pits inside an aircraft hangar with concrete. Pits are 5ft by 5ft and 5ft deep in size. My questions are: do I need re-bar, what is the best solution to avoid shrinkage. Any feedback would be appreciated. previously pits were used as media reclamation and all sides are concrete wall. Pits fill shall support large size aircraft (eg. Boeing 737). currently the pits are full of water and exposed for surface drainage. it is easier and faster to fill the pits with complete concrete and cost is not a problem.

 

[BadgerPE]

If possible, I would pour a 500-1000 psi slurry mix up to whatever your slab depth is. No reinforcing necessary. Then I would put 2 layers of 10 mil vapor barrier down to act as a bond break between the two pours. Top pour would be reinforced and doweled to the existing slab to prevent any joint movement. Although this is two pours, the contractor may prefer it because it will be easier to control the cure/finish of a 8"+/- slab instead of a 5' mass of concrete.

 

[PittEng88]

Or you could backfill the pit with some type of compactible stone such as 2A Modified. Then place your slab as Badger has suggested.