Removing AR stains from Tarmac/asphalt and concrete

[setanta]

Hi, As you may have guessed I was a bit sloppy and spilled some on the tarmacadam driveway and the concrete path. The AR was rich with copper and left a blueish green stain that I am having a very hard time removing from the concrete especially. Citric acid seems to have removed the majority from the driveway. I have tried hydrochloric acid which was not that effective and also sulphuric which was a bit better but didn't remove the worst of it. Nitric is too expensive and hard to find in Ireland to waste. I should also add I was scrubbing with a deck scrub and powerhosing the concrete up close and it still wont budge. Any suggestions would be greatly appreciated
I should also not I also have nasty rust like stain from fertilizer spill that wont budge either so.
Setanta

 

[butcher]

The cement (concrete)will be basic, and can reduce the ions in solution to metal, and reduce acids to salts.

These stains can also soak into the porous concrete, staining the concrete well below its surface.

HCl is used to clean concrete (it will actually dissolve the top layer of concrete, cleaning its surface, (if the concrete is not oil soaked which can help to prevent the attack from the acid).

Depending how deeply this penetrated your concrete , you may (or may not) be able to clean up these stains.

I would try HCl alone, and then with an oxidizer like sodium nitrate (or one of the other strong oxidizers), to see how much you can get the stain out, and then grind into the concrete cat liter, sweep it up.
and see if that helps.

Asphalt is a different substance, you could recoat the asphalt after cleaning it off as much as possible, acid would not be much good to use on asphalt.

I am not sure what Tarmac is?

Spills happen wherever you will be working, containing them is good practice, and working where these spill will not do damage.
But of course you learned that now.

 

[Anonymous]

Butcher

Tarmac is a brand name for asphalt. We call it tarmac over here in the UK but I think it's what you refer to as asphalt. Hope that helps.

Jon

 

[setanta]

Tarmac had to be recoated and tried all comercial products on concrete and HCL was the best. thanks