Any ideas on how to remove concrete stains from brick?

[nataliecampbell]

So the concrete has now been removed (see 4 Dec post) and there is quite a lot of the brick floor in place - although a channel has been dug out of the living room floor at some stage we are planning to restore this section with reclaimed brick. However, some of the bricks do have some concrete staining and small bits of concrete still attached - does anyone have any ideas on how to remove these?

View attachment 2

View attachment 1



thanks

 

[middi]

This is a dificult one. Since cement is ( usually) harder than bricks if you attempt to scrape it off will inevitably damage the brick face, if you use brick cleaner it will probably have no effect on the cement. If you transpose the brick face ( turn them over) it may not have the same patina. You can try a combination of the above in very small batch and see if it is acceptable from your point of view.

Alternatively hunt around for similar used brick from reclaims. Not an easy one to solve when vandals have not taken care of brick face.

 

[Lime]

I'd go to a builder's merchant (a proper one, not b&q) and buy 5ltr or more of brick cleaner that contains phosphoric acid.
Use this chemical with care.
Pour a quantity of the brick cleaner in a washing up bowl (or similar) and, using a paint brush, brush on the brick cleaner one brick at a time.
Wash off when the fizzing dies down (rubber gloves on) with a sponge and warm water with a couple of drops (not a squirt) of washing up liquid in it.
Repeat as required.
Avoid the grouting between bricks if you can.

Phosphoric acid removes cement quite well.

 

[Moo]

Your brick looks very similar to the state our pamments were in (and we, too, had a couple of trenches dug to take various heating and drainage pipes).
I used the method that Lime recommended, though I bought some HG cement remover and although it smelled disgusting and took ages, it worked a treat.

Good luck - that floor looks wonderful!

 

[nataliecampbell]

Thanks everyone. We will try this out and I will let you know how we get on.

 

[chuckey]

I would second Limes reply with the folowing Caveats. The acid will soak into dry bricks, so to get the best bang for your buck, flood the area with water, so the bricks cannot soak up any more then use the acid. If the bricks are porous then the acid will soak in and not dissolve the cement on the surface. The acid will totaly disolve cement, but when its actually mortar (particle of sand in it), the sand will stop the acid getting to the cement beneath the particles, which are loosened. So find the stiffist brush/abrasive pad which does not damage the brick surface, and use this when the fizzing stops, then more acid. the effect of the acid is almost immediate so when it stops fizzing wait just, say 30 seconds, then mop up, brush more acid. .. I don't think that leaving it for ten minutes to "soak in" is worth it. Once the fizzing has stopped, the acid component is used up, and the liquid left is just soapy water.
Frank