Can someone tell me what this is please.

T

Trainerboy

New member
This is at a strip mall on the sidewalk. There is a new section of concrete that has this stain all the way down it directly underneath some guttering that leaks. The issue is that the stain is only on the newer section of sidewalk that is about 250' long. The older section is about the same length and has the same leaky guttering but without even the slightest hint of staining. I hit it with an extremely strong batch of sodium hydroxide and 200 degree water. Nothing phased it.
HELP!!
 

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Looks like a topical magnesium stains. Your success on removing it will depend how far it goes into the concrete. Either way you can lighten it up but I wouldn't promise your customer the world. F9 Efflo is the Chem to use on that.


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Trainerboy said:
This is at a strip mall on the sidewalk. There is a new section of concrete that has this stain all the way down it directly underneath some guttering that leaks. The issue is that the stain is only on the newer section of sidewalk that is about 250' long. The older section is about the same length and has the same leaky guttering but without even the slightest hint of staining. I hit it with an extremely strong batch of sodium hydroxide and 200 degree water. Nothing phased it.
HELP!!
Click to expand...

I was thinking since the stains were just under the leaking gutter line that it would be calcium carbonate.
Take Craig's advise not mine. He is the mineral stain guru. And wish he would give a class on this topic. I would be the first too sign up!



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chrishartje said:
I was thinking since the stains were just under the leaking gutter line that it would be calcium carbonate.
Take Craig's advise not mine. He is the mineral stain guru. And wish he would give a class on this topic. I would be the first too sign up!



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Click to expand...

It does kind of look like a calcium stain but the difference is in the texture of the surface. Calcium becomes smooth. Built up magnesium maintains the original look of the concrete.


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