Bricks, Masonry, Asphalt and Concrete - Portland cement - laying it on a wall

Hi,
i want to use portland cement on a section of wall that has stone rocks on it. I have already taken an air chisel to knock down most of the high spots.

All i want to do is lay a foundation on this wall to lay some tile. The issue is that I need the thickness of the cement to be about 3/4" thick or so in some places. ( i need to bulid it out) other places even less.

how thick can i trowel on cement to a wall? do i have to do it in layers to build up that thickness? any suggestions?

would appreciate it
thanks

fdonger

Portland cement alone will not work. It needs to be mixed with sand or silica flour for it to get hard. It's just the "glue" that holds the sand together, and the sand is what has the strength. If you were to simply use portland cement, it would be smooth and easy to work, but you could scratch it off with your fingernail after it was cured.
With the sand in it, you can easily build it out 3/4 of an inch. I would suggest also mixing in some acrylic fortifier or bonding agent as well. This will add strength and make it stick better.