Broken Concrete Repair

      

REPAIRING BROKEN CORNERS AND EDGES OF CONCRETE STEPS, WALKWAYS, CURBS, PORCHES:
The corners and edges of steps and walks, and other similar surfaces, are another common masonry repair problem that homeowners face. Repair is simple:

1. Brush off all crumbling and cracked edges, and any debris. Wash the area with water from a garden hose or bucket and a stiff broom.
2. Use a carbide-tipped masonry bit in a portable electric drill, or a star drill and baby sledge hammer to punch 1/4-inch wide holes about 2 inches deep into the edge of the concrete. Space the holes about 1-1/2 inches apart. Two inches is okay if you have the room.
3. Force a tad of soupy mortar mix into the holes.
4. Drive lag screws or carriage bolts into the holes, leaving the heads protruding about 2 to 3 inches Do not position them too close to the edge of the work. The technique is illustrated on page 1.
5. Build a wood form from boards to create a new corner or edge.
6. Remove all dust and debris and hose down the surface with water, or broom it on.
7. Mix up 1 part Portland cement and 4 parts sand, with just enough water to allow the mix to be placed into the form readily. Or, you can use a ready-to-mix or premixed concrete patching compound for this job.
8. Place, then tamp, the patch into position. With the straight edge of a board, level (screed) off the excess concrete mixture or patch so it is level with the surrounding hard surfaces.
9. Let the patch set for 30 minutes or so and then trowel or finish the new patch to suit.
   If the chip is a small one, and you still have the chipped-off piece, you may be able to "glue" it back into position with a latex-based cement. You can buy this stuff in small packages; it is expensive.

LOW SPOTS IN CONCRETE:
If you can't level the low spot by lifting the slab or piece, this technique can be used:

1. With a brick chisel and baby sledge, roughen the surface and undercut any edges.
2. Drill several shallow holes in the concrete depression, using a star drill and baby sledge or a masonry bit in a power drill.
3. Mix a soupy mortar and then place and level it in the depression. Wait 30 minutes or so and then finish with a trowel or broom to suit.

What you are doing is called "veneering." It is our recommendation, if the patch will be a "this" one, that you buy a latex-based concrete patch and use this for the veneer rather than a standard Portland cement mix. The latex (sometimes epoxy) binders will hold the veneer in position longer and the material can be feathered out with a trowel to as little as 1/8-inch thickness (depending on the product; read labels).

BROKEN CONCRETE:
If the area is badly broken and unsafe it should be replaced before someone gets hurt.

How much needs to be replaced will depend, of course, on how bad the damage. In all cases, the first step is to dig out the soil at the edge of the slab. Then, with a brick chisel and baby sledge hammer, break away any crumbling edges until you reach firm, solid concrete.

Insert reinforcing bolts or rods in all edges and place the broken concrete pieces in the center of the patching area as "fl" stones. Place a standard concrete mix of 1 part cement, 2-1/4 parts sand, and 3 parts gravel into the hole. On larger patches, insert horizontal metal reinforcing rods across the bolts. E-3 rod is plenty heavy enough for this job; you can use a hacksaw to cut lengths to shorter pieces. Also, this is the type of patch that ready-mixed concrete in an 80-pound bag works to your advantage. An 80-pound bag yields about 2/3 square foot of patching mixture.

Once the patch is in place, level it and then trowel or broom to suit your design tastes.

Keep the patch damp with water for a couple of days. The water will help "cure" the patch and make it stronger. You can cover it with plastic, if you want.

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