This is working with a flat concrete slab, but imagine what it would be like on a vertical brick structure. Your Mortar Mix had better be perfect, especially if you’re dealing with an old building and don’t know what the mortar mix is to match what’s there. If it’s analyzed you know before you go.
Here’s a cool tip or two on dealing with cracked cement slab.
“HOW TO FIX A CRACK IN CONCRETE
I’ve been busy fixin’ stuff!
There was this crack in the concrete walkway at Mom and Pop’s house that was driving me nuts, so I repaired it and thought I’d share all the super simple fix-it details with you.
The crack had been there forever, but it only started driving me crazy recently. You see, it wasn’t all that noticeable until I finished installing the new stamped concrete tile driveway…
At which point the crack, in the walk way on the left, stuck out like a sore thumb. It was very rudely screaming at me: FIX ME!
And since I don’t like being yelled at, I did.
Here’s a close-up of the bugger…
You can see how the cracked corner sits lower than the rest of the concrete slab. So my plan was to dig up the cracked end and place a layer of sand underneath it so that it sat level with the rest of the slab. But the darn thing wasn’t having any part of that. As I dug out the soil on the end, I found that the piece was not only six inches thick, but it was still completely attached to the post on the right.
So I put my thinking cap on and came up with plan B: fill the crack with mortar mix and then use the mix to level out the top. And, I’m happy to say that it turned out perfect.
I used my chisel to create a small under-cut below the lip of each side of the crack.
Basically, your crack should look more like the image on the left above. The difference is that in the years down the road, the undercut will help prevent slippage of the repair.
Next, make sure your surface is thoroughly clean of any oils, dust, or debris.”