Concrete Floor painted but not dry ><

[Mark48]

As the subject suggests....

I had a patch of bad floor in my workshop re-concreted. Its right by the shutter door leading to the outside.

The guy who did it said to paint it after a week; I waited 4, then put PVA over it at his suggestion, then painted it with floor paint a day later.

The floor paint on the remainder of the concrete, brick walls, has been fine - great in fact. But on the new concrete its still mildly sticky - if you put something heavy on it or step on it, it will come away on the item / your foot.

If any water is spilt on it, it just comes away.

So this is a nightmare, not least because I cannot stick down the weatherseal and dust ingress is an absolute pain without one.

So I don't know what to do to rectify it. My gut instinct is that if water makes it come away, I should pressure wash the paint back off. Then I'll have to wait until its dry, try and seal it better, and use an epoxy 2-pack paint.

Obviously it would be nice to take a shortcut. Is it worth trying a second coat of the existing paint (its called Tuffcoat floor paint and I do not know the makeup - but its not a 2 pack paint....) to see if that makes a better seal?

Or just try painting over this with epoxy paint?

The other issue is whether in fact this is not the concrete still drying, but wicking water up.

He had to dig pretty deep to get the thing done, maybe 60cm down and used a ton of concrete for a 2.5m x 1m area roughly. So I can't see with that depth, that its wicking - but if it is, its not terrible - cardboard left on the surface does not become wet.

My final option is to find some kind of rubber surface to cover it in - its for working on cars and is right at the entrance so I need to be able to drive over it and use axle stands/ramps on it safely.

I hope thats enough information and would greatly appreciate some advice.

 

[dcdec]

I don't know much about concrete or floor paints but you never PVA anything before painting, that would be a good reason why its coming away. You should be able to scrub it off with hot water, once dry apply a thinned coat (25-30%) to the area, then full coats.

I can also tell you i allow 3 months for sand and cement rendering to dry out even in the summer, so 4 weeks for concrete may well not be enough time, could be wrong though not really something i know alot about, but hope it helps.

 

[joe-90]

It takes months for concrete to dry out. Leave it until the spring.

 

[Nozzle]

I'm going through the process of two-pack paint at the moment - I can tell you without a shaddow of a doubt it is way too expensive to slap on in the hope it wont come off! It'll only ever be as good as the substrate, and if that's peeling away the 2k wont last either. It needs to be dust free and rough, so etch it with a little brick acid first (don't forget to protect your eyes and skin). As for removing the PVA... tried a steamer for wall paper? Then slap down some newspaper and peel the sludge away. Do so until there's very little left, then chuck down some saw dust and let it all re-set, then scrap away. There is a temerature limit to concrete so dont go crazy with the steam. Builders seem to recommend PVA for everything??

Nozzle

 

[Mark48]

Thanks guys. I had no idea it could take so long to dry. What is weird is that on the run outside, its set rock solid. I guess as this was a much thinner piece and out in the open, its dried much quicker than the inner slab.

Simplest explanation is usually correct - its just not dry.

Why I was given the PVA, I don't know, I just assumed it was correct for fresh concrete. When I painted the existing concrete I used brick acid followed by a sealant primer.

So for this bit, I'm just going to shove some polyprop garage tiles over it, the ones that are like a very fine grid, so it can breath but it isn't sticky and marking off on tyres/stands/anything that rubs against it....

It'll be sticky enough to hold them in place to a certain extent, and then I can use it while it dries out properly and strip & paint it in the spring.

I'll give the area right under the shutter a bloody good scrub with hot water - then run a belt sander down it; it should be only about 15-20mm deep at this point so hopefully dry enough to get a good adhesion for the weatherseal.

FYI: The 2-pack was not going to be much more than the floor paint I bought! £52 for 10kg, compared to £35 for 20L of the floor paint. Its not a big area. The floor tiles will be about £40.

Thanks again chaps,