basement concrete floor/ceram. tile prep.

[vdotmatrix]

THe concrete floor in the basement had some type of non ceramic tile which I am replacing with ceramic tile.

the old adhesive used to stick the old tile was black and tarry and but now it is hard and dry...Do I have to remove this before I use the ceramic tile adhesive or will the quick set mortar adhere just the same?

[HayZee518]

If the surface is hard - doesn't soften during normal day to day activity I would say go ahead. But if during the warm times it gets soft for any reason I'd look into removing it right to the substrate. Use a propane torch to soften it and scrap it off to the concrete. Sure its gonna be messy but you don't want tiles shifting. You've got to get a bond between the tiles and the concrete. You don't need stuff in between. For setting the new tiles use Quick-Set. It's mortar based. Once its cured use any grout in between the tiles to finish. Use a rubber float for the grout. Work the grount into the joints. After dry use a burlap to scrub down the joints and remove the haze that remains. Wash the floor several times with water. When dry use a paste wax to bring out the highlights.

[HayZee518]

Well - try using a belt sander with a 60 grit paper. Use a particle mask and a vacuum to clean up. To imbed the heating elements I guess it would be beneficial to use the same portland - sand mix used on a shower pan installation. This is kind of a loose concrete mix you make up and tamp into place with a hard trowel. It'll dry HARD! then you'll have a base for the tile. What I did for a shower base is use a five sand to two portland ratio. I used enough water to make damp mix, not soupy, not pourable. I applied the mix to the floor and tamped it down and trowelled it so its smooth. Then I let it cure overnight. Surprisingly it hardened. Next day I applied a second coat with some chicken wire embedded within. at this stage I'd say you could put in your radiant heat - maybe you could put it in on the first coat. Up to you.The second coat gives you the chance to even out valleys and high spots. When this is cured go with the quick-set and yout tiles. good luck!

[LazyPup]

The product you are dealing with is most likely "Black Asphaltum". Up unit the mid 80's it was used extensively in commercial or high traffic areas to cement commercial floor tile.

I worked in a school system in Massachusetts during the 80's and often had to deal with it when replacing floor tiles. We Commonly removed as much as possible with scapers then applied a thin set floor prep over it to prepare for new flooring materials.

[kactuskid]

You should take a sample in to get it analized, alot of old black cutback prior to the mid 70's contained asbestos and if left undesturbed causes no problems. But if you try scraping, sanding, etc, the fibers will become airborn and dangerous.

There are two Companies that make a Black mastic remover for your project. One is the Sentinel Company in Minneapolis and the other Dumond chemicals in New york (www.dumondchemicals.com. It will make your job easier and safer.

Otherwise, there are thinsets that are rated for applying overtop of cutback.