Filling an Existing Floor Pit 3

[steve1]

I need to write a specification for filling an existing floor pit with concrete. The pit dimensions are approximately 22' x 18' x 5.5 feet deep. A concern was raised that using a normal weight concrete would result in unacceptable shrinkage around the perimeter of the pit walls, and that I should consider going to a "low shrink" concrete. I am not familiar with that type of mix design. Can anyone provide an insight into "low shrink concrete" and or any potential problems with filling the pit with normal weight concrete.

 

[boo1]

Why fill with concrete? Invvestigate engineering fill with a slab. Peremeter thickening, dowels and reincforce as required.

 

[jsnowe]

It does seem like an expensive fill.

 

[steve1]

I agree with engineered fill capped with a concrete slab which is what I'll be recomending when we meet with the client and contractor next week.

The pit partially surrounds two turbine generator foundations. The turbines have been removed and one of the existing inertia blocks is being incorporated into the foundation of a new HRSG. The HRSG has been located in an unfortunate spot where it will partially overlay the pit on one side, pass over the pit wall, and overlay an existing concrete slab on grade on the other side.

 

[dbuzz]

I would also recommend compacted select fill topped with a reinforced concrete slab.

 

[BigH]

Why not use a flowable fill - I used to use a material called K-Crete (years ago) - am not sure of newer "names". It goes in like concrete, is less expensive but you don't have the problems with filling in layers, compacting, density checking, etc. All these items add up and, in fact, may turn out to be a bit more expensive than a single day pour. We did this in a big pit in Scarborough back in the 70s - contractor loved it.

 

[steve1]

Thanks for the tip BigH. I did a google search for flowable fill and found lots of good info. I will investigate this further when I return to work tomorrow.

 

[BigH]

Steve1 - might try the following website in particular.

http://www.maxflow.com/