Concrete Tank Walls 1

[132435465768798]

What are general concrete code requirements for the thickness of interior concrete walls in a chlorine contact tank? The tank is underground less than 10 feet, and has 6" concrete baffled walls about 24'long. Not sure exactly how ACI code applies here. THe only load on the walls will be grating and occasional person. Not looking for detailed design info, just general code info, any rules of thumb, or the best place to get more info. Thanks!

 

[rethornton]

The Portland Cement Association (

http://www.portcement.org)

has a publication entitled "Underground Concrete Tanks" that contains general design and construction guidelines. Another reference is ACI 350 "Environmental Engineering Concrete Structures".

 

[kenvlach]

Hi,
I’m not a civil engineer, but in the metal finishing business, chemically resistant bermed areas are required. For concrete pours, we use a high strength (6000 psi), stiff mix for a low shrinkage, non porous, high density concrete. After curing, a penetrating concrete sealer is applied before adding a liner.

For your case, the lifetime of the tank will be limited by chlorine-initiated attack on the rebar. This attack can be minimized by using high density (low porosity) concrete, a sealer, epoxy-coated or stainless steel rebar, and galvanic protection. I assume that you will be taking some measures, and maybe rethornton’s references cover the subject as well. I suggest that you review previous threads (thread507-14533,thread592-40952, thread338-43027) on corrosion of rebar. Perhaps, the first 2 or 3 preventative measures I listed may be cost-effective when maintenance, reliability and lifetime are considered.

Also, a quick search for sealers found the following:

“SUPER~SEAL Penetrating Concrete Sealer is recommended for:
Any exterior exposure subject to freeze / thaw attack.
Marine structures such as docks and piers subject to attack by water and chloride intrusion.
Bridge decks and parking decks that are under constant attack by oil, water and de-icing salts.”

http://www.lsepoxies.com/Super-Seal.html

 

[JedClampett]

I've done designs of similar facilities. I'm assuming you're asking about the baffling walls that increase contact time in the tank. Their design is such that you can never have liquid on one side and not the other.
There's no real guidance in ACI 350 or 318. I've seen eight, ten or twelve inch walls used. Most of the time. these are exposed and wind controls. I've even seen tilt-up walls used.