concrete slab pour limits

[structengineer]

I have a 100 foot diameter tank which holds water and we are requiring the contractor to place the slab for the tank in 4 sections (around 2000 square feet). They have come back requesting to place the slab in one pour. Our concern with one pour is the greater chance of shrinkage cracks.

As a question to other engineers, is 2000 square feet pour seem typical for a water containing structure? Is there something in the code or other documentation that I could throw back to the owner?

 

[TDAA]

How thick is the slab? Do you have any control joints planned with water stop?

 

[structengineer]

The slab thickness is 12" from the center to the radius of 43 feet where it transitions to 1'-6" to the perimeter of the slab. We were not planning any control joints in the slab.

 

[MotorCity]

If the base layer(s) and joints are adequate, the only limitation I can see would be the capability of the concrete suppliers, finishers, etc. Industrial plants, warehouses, highway projects pour areas much larger than 2000 sq ft very often.

 

[SlideRuleEra]

Should be ok. Proper curing is probably the most important issue remaining. If you choose to allow the Contractor to proceed with one pour, suggest that in return you REQUIRE him to properly wet cure the slab for a full week - even if the spec allows other curing options.

http://www.SlideRuleEra.net

 

[lkjh345]

A few random thoughts:

How much reinforcing are you using in the slab? With the proper amount of reinforcing, this size of a pour is very doable.

Using around 0.5% area of steel I have had warehouse floor pours considerablly larger than 10,000 SF. Have done paving 'lanes' in other warehouses that were in the order of 400' long (x 10' to 15' wide) with very few hairline cracks.

Also, look into the concrete mix. Keep the w/c ratio as low as possible. There are also additives the can compensate for the concrete shrink, those these may be fairly pricey.