[Richy L]

Any idea how to remove this staining? The slabs have turned orange, not the grease marks, the orange staining.
I can't see what has caused it. There appears to be no metal above, no rust nearby.
The areas are under canopies(6 different areas). There is no staining anywhere else on the site on these slabs  except these areas under the covers.




And the third pic is over granite stone. Look like lime from the cement? how would you remove this?

[Richy L]

Any ideas? this is part of a large job and I need to factor this into my quote.

[Matt Gibson]

On the steps it looks like there is a bit of efflorescence there. Hydrochloric acid might shift it, but it looks pretty heavy.
You could try wetblasting it. Not sure about the other staining, i cant quite see it. You say the staining is only under the canopies? what are the canopies made of? metal? could be rusty water running down off the canopies.

[Richy L]

No rust. it is at the entrances of the building, so there is a no rust above it. It is well under the cover where rain would not get to, even drips would not get to it.





The problem is not under the glass canopy, but right under the building by the doors. where the rain hits there isnt a problem

[Matt Gibson]

Hmmm..

Could be something spilt? does it look like a spillage of something? does it feel greasy or anything?

Just quote a bit extra for the hassle, and take every chemical you have with you and give it a test.

[Richy L]

No, its not a spill. it in the same type of place over the site.
I have spoken to Tensid and they're not sure either but have recommended a few to test. I have submitted a quote fora test clean with the chems advised and we'll see what happens.

[Matt Gibson]

It might be the slab. A rubbish batch or something to do with the make up of the slab.