Insufficient cover for concrete column

[asixth]

Hi

I have a column that for one reason or another has insufficient cover to the reinforcement. I am saying that it is non compliant because durability, fire rating and strength are compromised. The cover required is 1-1/2" and the as built cover is 1/2". They are not going to like it when I tell them to knock it down and try again so what are the other options to provide additional fire rating. It is a carpark so plenty of exhaust fumes and I am willing to accept that paint will provide the protection for durability.

Any advice will be appreciated.

Thanks.

 

[JAE]

Simply add fire protection over the existing condition - either more concrete, layers of gypsum board, etc.

 

[DST148]

Since it's a parking structure, you would need both - the environmental and fire protection. Before you decide on knocking it down, try something similar to strengthening of column by section enlargement.

 

[Teguci]

You can calculate the strength of the reinforcement at temperature based on the available concrete cover. The durability issue is a bit stickier. Paint might work for a few years but in the environment I typically deal with (high chlorides) the splash zone will eventually start spalling due to corrosion.

 

[rowingengineer]

The choose is yours, you can add extra protection thru other means or you can make sure that you never have to worry about a contractor on your job again stuffing up cover, by telling them to pull it down.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[JedClampett]

Sika makes a coating called Epocem that supposedly adds corrosion protection through concrete cover.
While not as drastic as ripping down the column, having to buy and apply 15 or so gallons of that stuff ought to give the contractor something to remember.

 

[hokie66]

If nothing has been cast on top of the column, I don't think it is drastic to require removal and replacement.

 

[asixth]

Good news, they're going to demo and replace. Interesting though, their appeared to be dark marks on the column surface at the ties location. Think the mix was 10mm aggregate and 120mm slump. Has anyone else noticed these marks on columns when cover is too small?

 

[ishvaaag]

Marks of oxidation? Sometimes at joints poorly made (in columns, maybe) ... in floors the oxide most commonly is seen through the gypsum finish...

 

[ajk1]

Having spent most of my engineering career on parking garage durability, I agree with hokie66. Just tell them to remove it. The owner is entitled to have a building that is not a band aid job. It is not that hard to remove the column, particularly if the concrete is relatvely young and if it won't hold up the schedule significantly. If it is a schedule issue, may have to accept the bandaid.

 

[asixth]

Has anyone applied an intumescent coating to concrete?

 

[DST148]

Try

http://www.flameoffcoatings.com/concreteassemblies.htm