Cleaning Concrete

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Cleaning Concrete

Postby Mr. Chang » Wed Jun 21, 2006 12:09 pm

Can anyone tell me the best way to clean up concrete. The house has just been finished, but there are assorted stains on the concrete outside the house. Some are from paint, but others are not.

Are there any special products out there for this purpose? It would make the whole place look a lot nicer if these stains could be gotten rid of. :?
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Postby John » Wed Jun 21, 2006 5:36 pm

The porous surface of concrete or brick can make stains that have penetrated difficult to remove. Water based paint for example can penetrate the surface to a depth of several millimetres making it almost impossible to remove the stain.

Solvent based paints try paint stripper/remover but beware the solvent can carry the stain deeper into the concrete.

Mortar stains try mortar/brick cleaner (hydrochloric acid)


High pressure water jet with an abrasive injection is very good for cleaning concrete.



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Re: Cleaning Concrete

Postby H... » Sat Dec 05, 2009 11:36 am

BUMP

I've got a large area of stone-wash to clean from cement debris and mould stains - some 350M2.
Any one purchased a pressure washer to do this kinda work before? Brands / models / supplier recommendations?
I'm guessing apart from the pressure washer i'll need a wire brush for the worst bits of cement and a stiff brush for general stains also a big tin of acid.

After cleaning i thought applying silka sealant to try and stop the mould coming back would be a good idea - any tips?


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Re: Cleaning Concrete

Postby geordie » Sat Dec 05, 2009 9:59 pm

just a caution the jet wash i use in the uk is a high power job i think 140 bar

it will on a needle jet etch concrete cleaning stonewash i am no expert but having seen it laid i would be reluctant to blast at it with a jet wash
if its algea removal try bleach and a stiff broom cement stains can be removed with acid but its likely if you are not careful the stonewash will get damaged try a small area first apply with a paint brush so its concentrated only on what you want to remove as a rule of thumb when it stops fizzing apply again and use plenty of water to wash down after and by the way yes the sealant is a good idea even if a little late?
my comments may be wrong but never deliberately
If it aint broke, dont fix it
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Re: Cleaning Concrete

Postby H... » Wed Dec 30, 2009 11:49 am

So got myself a k'archer pressure washer, stiff brush, wire brush and some acid - the cement stains / lumps still are proving a complete bugger to clean off - they have had 9 months to to cure onto the stone wash.

The floor is coming up pretty good (Will seal the floor in a few days - anyone recommend a brand/product?) - the walls which have a black dye in the stone wash mix are really not getting any better even with neat acid on them - mostly what happens is the acid is removing the black dye (me thinks the original job was pretty naff quality)..............for the walls i am thinking of cheating a bit and using a black concrete roof/floor paint, i still want the 'stone wash' look but with a constant colour throughout and something that isn't going to have to be re done too often - HELP!!!
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Re: Cleaning Concrete

Postby geordie » Wed Dec 30, 2009 5:32 pm

apply the acid several times using a soft brush do not put any water until you are sure you have acheived what you want regarding the walls/dye the dye adheres to the cement during the mixing stage so acid will bleach it as it is removing the cement if its not too large an area try shoe leather dye I used it to patch my pattern print where i had been heavy handed with the jet wash all the uk sealants are xylene base so i supose if you find something similar to use one thing though if they did not put polythene under paths you can still get staining from under the concrete it will soak through
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