Intermediate Question Whats this?

[Doug Dahlke]

Anyone know what this stain might be? It is on an upper level of a shopping center under a canopy. In the photo it looks like rust but I don't think that is what it is. Any ideas?

[Ron Musgraves]

look up, its coming from the roof I bet.

[Scott Stone]

It could also be coming from the concrete itself, from the reinforcing rebar. Most likely it is from teh canopy above. Remember, rust that develops on the canopy will wash down onto the concrete beneath. You are also seeing how the water flows to the drains.

[Doug Dahlke]

I will be in that area tomorrow. I'll take a look above the walk and try and get some more pics.

[MMI Enterprises]

Concrete rebar should be deep enough (2" or greater) to not pose such issue. When it is embedded within and the crete is at proper alkaline levels there is a natural coating that occurs to it. Is why it is not good to overdo acidic cleaning processes on concrete. Concrete fails once the protective alkalines leach out and only then can the rebar go. Normally it would take many years to occur.
This issue looks to be water run off that contains minerals that are oxidizing/rusting/aka staining. Try phosphoric or oxalic acids to remove then seal it with a good impregnating type seal.

[Doug Dahlke]

Here are pics of the canopy. The center was built in 1988 - 89. Since the stains are only in certain areas I wondered if maybe when the rails were painted in the past the prep work caused the stain. I am pretty sure I will end up doing this center very soon. If they tell me to proceed I may go out there and test a few places with ox or Safe Restore.

[James]

That was the first thing I thought of was the rails?

[Doug Dahlke]

I was just quoting another center that is run by this same PM company. This one is 70 miles away and has the same type of orange stains in the concrete in various places. There are no rails at this center and I couldn't see anything nearby that would have caused the stain. Very strange.

[Paul Kassander]

It could have been something in the mix of the concrete with a high iron content. More than likely they used the same builder who used the same concrete company.

[James]

Well did you bring any Chems with yah so you can do a test spot ?

[Doug Dahlke]

Originally Posted by James

Well did you bring any Chems with yah so you can do a test spot ?

No. I am an idiot. I had another quote to look at today besides this and was taking care of some other things first thing in the morning. I had planned to bring some Safe Restore but half way to the first quote I realized I never put it in the truck.

The first picture I posted is at a center only a few miles from me. I'll try and get out there over the weekend to give some stuff a try.

[Doug Dahlke]

Made it to this center early this morning before the stores opened and people were around. Tried some Safe Restore on this and as soon as it hit the stain it started to foam. I only let it sit a few seconds and rinsed it off. Staining gone.

[billrt]

Good to hear, But don't you thing safe restore is a little high priced for sidewalks
Bill Regan
Regan and Son Power Washing

[Doug Dahlke]

Originally Posted by billrt

Good to hear, But don't you thing safe restore is a little high priced for sidewalks
Bill Regan
Regan and Son Power Washing

Bill,

Probably true but for what I would get for this center it would be worth the expense, especially since this would be a new PM company for me. I would hope this would lead to more work with them. I would only need to use it where the stains are which is not a large part of the overall walk area.

As quick as the SR worked on this it could possibly be diluted saving on the expense.