A Discussion on Efflorescence 1

[umrce]

I've recently had a client claim that the efflorescence from a beam was dripping onto cars in their parking garage and removing the paint on the tenants cars. I've never heard that before and as a young structural engineer was under the impression that other than helping me locate cracks, these calcium deposits are purely an aesthetic concern. Any care to educate me a little more on this specifically and efflorescence in general? Thanks.

 

[JAE]

The water coming through the concrete (and leaving the efflorescence would potentially have "ingredients" that could harm car paint.

Here's an article that describes some of the chemical composition of the process.

http://www.concreteconstruction.net/concrete/what-causes-efflorescence-and-how-do-you-remove-it.aspx

These are soluble salts in the water.





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[umrce]

-JAE

Thanks. While it could have the "ingredients" it seems likes parking garages would be excellent places for efflorescence to occur and cause this problem with cars however I've never heard of this problem before. Do you think this would be a more unique circumstance? I've never heard of this before which makes me believe this is not a routine problem.

 

[Ron]

Efflorescence is common. It occurs in/on any cementitious material that water migrates into and then out of. As water goes into the cementitious material (mortar, grout, stucco, concrete, etc.), the calcium constituent of the cementitious material is so plentiful (generally over half of the compounds in cement contain calcium) that the water takes some of the calcium in solution. When it comes to the surface of the concrete it dehydrates and reacts with carbon dioxide at the same time,creating calcium carbonate...the white stuff. The chemistry can be a bit more complex and contain other compounds as well, but that's the basic stuff.

Can it damage paint on a car? Sure. Most auto paints are acrylics of some sort. They are solvent based. Even though they are "shiny" they are porous to some degree. Further, the efflorescent compounds can be abrasive as well. Further, if the efflorescence imbibes some pollutants such as petroleum products, it can clearly damage paint.

 

[JAE]

Knew you would show up eventually!


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[Ron]

JAE...spring starts this week....TPC starts in about 8 weeks...time for another beer. I'm thirsty! I'll buy.

 

[JAE]

You know what? My brother-in-law is moving out of state. He sold his house which was about 1/2 mile from Sawgrass.

I may yet still think about it though. So enjoyed it several years ago.



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[darthsoilsguy2]

you could look to see if there is a way to reduce the amount of water accumulating and dripping. don't know what floor the problem is on but some ideas.... sealing penetrations, creating tooled drip edges at non-parking spots to prevent water from traveling across a member and dripping on a car, adding a drip edge feature or strip at good spots to break the plane and prevent that accumulation, concrete crack sealing, putting a traffic coat down on the top floor....

If it is really bad, you should be able to see the evidence in the worse spots on the structure above. also, i'm sure the client will let you know which tenants are giving him grief.

 

[hokie66]

Leakage through parking decks is unfortunately common, due to lack of a membrane and/or adequate crack control reinforcement. And yes, it does damage the paint of automobiles. The problem frequently goes unnoticed or not addressed in transient parking decks, but in residential or office parking where cars sit in the same spot each day, it can be a big issue.

 

[umrce]

Thanks for the input everyone. The responses have been very beneficial/educational.

 

[darthsoilsguy2]

My buddy sent me this link and it reminded me of this thread. lots of photos...

http://www.reddit.com/r/RealEstate/comments/31qz37/dust_in_parking_garage/

 

[hokie66]

darth,

That is an extreme example of what we have been talking about. The first question that guy should have had was..."Why is my car the only one here?"

 

[darthsoilsguy2]

But Hokie, the photo caption says the garage was "generally usable and acceptable".... what else could you want in a garage?.... I'm just hoping it isn't the EXACT example of what we've been talking about.

 

[hokie66]

Not usable for my car. The photos tell the story. Lots of water penetration, spalling of concrete due to corrosion of reinforcement. Not just an efflorescence issue, IMHO.