how to repair a concrete patio slab with crumbling edges

Question

A brick-on-sand patio was added to the house back in the 1970s atop a poured concrete foundation that goes down 36", below frost-depth, per local code. A brick-veneer was adhered with mortar to the outer wall of the concrete slab.

That veneer had no foundation beneath it, and so, with the passing years, the veneer has peeled away from the slab. With nothing to hold the outer pavers in place, they too have worked themselves loose. Prior owners tried the temporary fix of putting some mortar between the bricks, but that has cracked and they've worked loose. The outer edges of the concrete slab have begun to crumble.

I could use a demolition chisel to remove the paver layer pretty easily and then clean off the sand and power-wash everything. But how to repair the crumbling edge of the concrete slab so that it has a nice clean edge that will hold up over time?

To repair the corner, should diamond metal mesh with a 90-degree bend be pinned to the face of the slab using a concrete pin gun and then a layer of cement applied to the mesh, to shape a new 90-degree cement edge?

Answer 1

Interesting issue...and seems there are a few things taking place. I'm going to break my recommendation down to two different parts:

Repairing the Crumbling Foundation

You want to ensure that any patch/repair is not built on top of compromised concrete. As such, i'd recommend the following:

1. Remove brick/sand from the edge so that you have a 6-12" of clean, uncompromised concrete.
2. Clean the concrete that is crumbling. This means removing any loose pieces, chisel out anything that looks suspect, and take a wire brush to the surface. If possible, it also helps to power wash that area at the end.
3. Install some rebar (match size and amount of rebar to the size of the repair) into the existing foundation. Drill into the concrete, insert rebar/concrete adhesive, install rebar. This will help insure a bond to the exisitng foundation when you pour the new concreate patch.
4. Build a temporary frame at the edge of the foundation. I'm not sure, based on your drawing , if this is just one edge based on your drawing, but just imagine that you're going to follow the existing footprint of your foundation and simply need to contain the new concrete when pouring.
5. Mix and our new concrete. Finish as appropriate.

This will provide you with a new, solid foundation with a clean, strong edge four your sand and brick. Next:

Install Brick Fascia

1. If these are full bricks, I would recommend pouring a small concrete footing for them to rest on and stabilize.
2. If this is fascia brick, you'll need to install wire mesh on the foundation wall and then mortar the brick onto the wire mesh as you would normally. A concrete footing wouldn't be necessary for this.

Those are my thoughts, hope it helps!!

Answer 2

Just build a little form around the outside of the slab edges about 4" out from the edge. And then fill it with concrete. Take forms loose. There's a clean edge. Or get high speed high strength grout, slap it on and smooth out the best you can.