grouting replaced 4x4 ceramics

[SteveNathan]

I had to remove 7 4x4 ceramic tiles from shower walls (not floor). Tile was set in a mortar bed. Most came out cleanly (with plenty of chiseling, scraping and grinding), but a couple of them resulted in damage to the mortar bed, with some cracking and some crumbling, and a little exposed mesh. After getting any loose material out, I want to patch the mortar but I'm not certain what the best method and material is for this. I've patched concrete sidewalks and stairs in the past, and I remember treating the break with a bonding agent first, and then using Quickrete patch, but I'd guess that I need to use a mortar product of some sort for this, and maybe also a bonding agent. Any advice will be greatly appreciated.
Thanks,
Steve

[Davy]

Hi Steve, welcome. A picture would probably help us but it really depends how deep the holes are in the mud. If there's lath showing, (mesh) then those areas are probably the deeper spots. If you can get most of the crumbs out of the lath, mason's mix mud alone would grab hold just fine. If there's shallow spots that are 1/4 inch deep or less, thinset mortar alone will fill them up. Any areas that don't have lath showing that are over 1/4 inch deep can be treated with a thin layer of thinset and then immediately filled with mason's mix. The thinset acts as a bonder.

[SteveNathan]

Thanks Davy. Your suggestions seem pretty clear, but here are a couple of pics.

[SteveNathan]

This was recommended by HD.

[Lazarus]

SIKA makes some good products and I haven't used this but it should work. As stated above, I would probably let it set and use a good modified thinset morter to actually set the tile. You won't need much and can frequently pick up a torn bag at HD for about half price...

[Davy]

It's hard to tell the thickness of the mud bed in those pictures. If it's 1/4 inch thick or less, use thinset alone.

[SteveNathan]

In order to replace shower glass with frameless, we had to remove and replace 20 tiles in our shower walls (none on floor). While we were at it, we removed any stained grout throughout, but did not remove or notch into all grout lines. When we apply new grout to the lines that need it, should we moisten the surrounding old grout with either a sponge or a misting spray bottle? Are we going to regret not taking down all the old grout, even though it is solid and strong?

[cx]

Presuming (I am) that is a cementitious grout, you'll not have much success matching the color exactly, but so long as you're grouting empty joints, that's the only problem you should have.

Originally Posted by Steve

...we removed any stained grout throughout, but did not remove or notch into all grout lines...

Not sure exactly what you might mean there, but with cementitious grout you must remove existing grout to a depth of at least 2/3rds the thickness of the tile to achieve much success. Scraping out just a little of the top portion of grout and re-grouting doesn't work well.

My opinion; worth price charged.

[Tool Guy - Kg]

I read this to mean they dug out the grout in a bunch of different spots.

Yes, I think you’re going to regret not grinding away all the grout lines to a 2/3rds depth if your goal is to have a nice consistent color when you’re done.

[SteveNathan]

Bubba read it right. We’re not worried about color because we plan to put a colored sealer over all of it.

[SteveNathan]

Still wondering do we moisten surrounding grout or not?

[ss3964spd]

I don't think I would, Steve. Adding moisture to the existing grout will also add more moisture to the newly mixed grout you are going to apply. More moisture can impact the grouts strength and ability to bond the tile edges.

[SteveNathan]

Interesting. The Bob Villa forum advised the opposite. They said where the new met up with the old, the old grout would suck up the moisture from the new grout too fast and weaken it.
Oh well. We just ran a damp sponge over all of it.
I think it came out looking good, and I can't actually see the color difference. We replaced about 20 tiles total, scattered throughout the walls and curb, and now it's hard for me to pick them out.

[cx]

Well, who are we to disagree with Bob Villa?!!

I would say that's an exceptional job, Steve.

[Davy]

I think Dan was talking about avoiding having everything saturated with water. That would be too much water like he said but a little moisture in the old grout wouldn't hurt anything and might help some.

Removing the dust is important in case someone else is in the same situation.