Black Stuff On Concrete.

[Sean Kelly]

There is black (looks like some kind of waterproofing) paint on a concrete kitchen floor. Ive primed it and its taking ages to dry. Any ideas what it is? I want to slc over it.

Its giving off some lovely blues and greens.......very strange.

 

[Flintstone]

Most likely some old bitumen glue type stuff used to stick down old vinyl tiles. Best option is to prime it with prime plus grip, or make a slurry coat up. Normal primer isn't the way.

 

[Qwerty]

Scrape off the worst lumps of the bitumen if any and then slurry coat it.
Here's one I did at the start of this week....

Remove, scrape, sweep, slurry, level, prime, tile (with great difficulty.... B&Q sizey rubbish tiles), grout, paid. Boom!

 

[Flintstone]

Nice little job. That slurry bond looks thick?

 

[Qwerty]

Nice little job. That slurry bond looks thick?

Yes, about 1mm thick. Fully covers all bitumen with zero chance of any oils leeching through afterwards. Scraped off the little lumps once dry prior to levelling

 

[Flintstone]

Interesting, I use the pre mixed stuff just stir it up and roll it on, dries like 80grit sand paper. Similar when I've mixed my own, what's your mix? Did it take forever to dry

 

[Sean Kelly]

Cheers Lads. I've come across a bitumen floor b4. It was a sticky residue on the concrete. This one today was like a paint but i could not scrape it off.

As i said i primed it.......It only took 1.5 hours to dry!

I went over it with BAL level max. As it said no need to prime i thought i would prime anyway.

 

[Qwerty]

No, it dries in a few hours. SBR & water mixed 1:2 with rapid set addy. It should really be 1:1 but the extra water makes it easier to roll on with a 4" roller