Using SLC over old thinset

[Eurocom]

recently just removed about 1000sqft of ceramic tile. I am not a floor layer by trade but demolition and removal is in my scope. I used a 6” tile bit to remove the tile, most of the thinset stayed on the concrete, spot that did come up created divets in the concrete slab. After removal I swapped to a floor sander with carbide bits, as it’s removed thin set with ease the other couple dozen times I’ve done this, no luck.

My plan now is to just self level the floor just high enough to cover the old thinset.

Any recommendations on a specific one to use for this application? I was just planning on using MAPEI self leveler as it’s the one I’ve used in the past, curious if there would be a better product for this application?

Thanks

 

[worksarc]

I've had luck removing thinset with a flat shovel and in extreme cases, with a masonry grinder cup. A small 4" metal scrapper could also work to remove the thinset.

The Mapei should work in this application, provided that the FFE isn't beyond tolerance.

 

[Eurocom]

I've had luck removing thinset with a flat shovel and in extreme cases, with a masonry grinder cup. A small 4" metal scrapper could also work to remove the thinset.

The Mapei should work in this application, provided that the FFE isn't beyond tolerance.

I did contemplate using a 9inch diamond cup grinder, but taking into account all of the patch work I would need to do even after grinding it all down, I figured just floating the entire surface would be worth the cost in labor hours saved.

Should I be worried about the leveler not taking to the concrete / thinset? Prior to install I’ll prep the surfaces with a thorough vacuuming and removal of any loose material followed by primer.

 

[worksarc]

Your approach seems to be the right one. The Mapei should adhere well to any clean surface. I would not think that you should need to score the surface of the remaining underlayment for adherence.

 

[highup]

I did contemplate using a 9inch diamond cup grinder, but taking into account all of the patch work I would need to do even after grinding it all down, I figured just floating the entire surface would be worth the cost in labor hours saved.

Should I be worried about the leveler not taking to the concrete / thinset? Prior to install I’ll prep the surfaces with a thorough vacuuming and removal of any loose material followed by primer.

I'm thinking of the thinset is bonded that well, applying SLC would be like sanding a car body with 16 grit before painting it.
Application of a primer might stop the thinset from sucking all the water out of the SLC and helping it flow. You might want to apply the primer with a cheap pump sprayer, then back roll with a thick paint roller. If you just dipped a roller in a tray of primer, you might end up with some thick puddles of primer.
......just a thought.
You owe me 2 cents.

 

[havasu]

If I were in your shoes, I'd get a grinder to finish the job. That SLC is expensive and if not poured all at once, you may end up with ripples, which will have to be ground down as well.

 

[C.J.]

Or if the thin set isn’t completely bonded to the concrete it could pop loose as the SLC is curing.

I remember the Ardex rep always telling guys to broom on their sealer (P51). I’ve used a roller to apply primer only because I didn’t want to toast a good broom. I wonder if brooming the sealer on, as opposed to rolling it, is so that it leaves ridges that the SLC can grab onto for a better bond. $5 says @Commercial Floor Rep knows the technical reasoning behind that.

 

[Commercial Floor Rep]

Or if the thin set isn’t completely bonded to the concrete it could pop loose as the SLC is curing.

I remember the Ardex rep always telling guys to broom on their sealer (P51). I’ve used a roller to apply primer only because I didn’t want to toast a good broom. I wonder if brooming the sealer on, as opposed to rolling it, is so that it leaves ridges that the SLC can grab onto for a better bond. $5 says @Commercial Floor Rep knows the technical reasoning behind that.

You can use a roller, but Ardex has always taken the stance that using an exploded tip push broom does two things that a roller won't. 1). It works the primer into the pores of the substrate better to achieve a better bond 2). It provides more of a "stippled" texture for the self-leveling to get a better "bite" to. The key is an exploded tip bristle though. Basically, that's just like the tips on our hand brooms that most of us generally use to do our final sweep. That finer tip allows the better penetration into the pores of the substrate. A stiff bristle push broom won't work.

 

[C.J.]

I had somebody broom on some primer with one of my good push brooms then they didn’t rinse it out when they were done. That irked me because a good broom isn’t cheap.

 

[Commercial Floor Rep]

I had somebody broom on some primer with one of my good push brooms then they didn’t rinse it out when they were done. That irked me because a good broom isn’t cheap.

Like not cleaning off a trowel or a bucket...nothing worse...GRRRR!

 

[highup]

You can use a roller, but Ardex has always taken the stance that using an exploded tip push broom does two things that a roller won't. 1). It works the primer into the pores of the substrate better to achieve a better bond 2). It provides more of a "stippled" texture for the self-leveling to get a better "bite" to. The key is an exploded tip bristle though. Basically, that's just like the tips on our hand brooms that most of us generally use to do our final sweep. That finer tip allows the better penetration into the pores of the substrate. A stiff bristle push broom won't work.

How about gravity feeding a pressure washer with primer
No pores scape the Almighty.

 

[Commercial Floor Rep]

How about gravity feeding a pressure washer with primer
No pores scape the Almighty.

With great power comes great responsibility…you must only coat the floor and not the entire room! I’ve seen people use spray adhesive, it can get ugly pretty quickly!