Patching Cracks in Concrete

      

It doesn't take a lot of skill to make repairs in concrete walks and driveways. It takes some muscle, however and you can get wet and dirty. The money you will save and the rewards of doing it yourself are worth it. There is one caution: always, without fail, wear safety glasses and heavy gloves when chipping concrete. In this How-To Booklet you will find patching techniques to make repair jobs go easier. We can't offer any special pointers on how to keep you dry and clean.

PATCHING CRACKS:
One of the most common masonry repair jobs is patching cracks in concrete. Before you patch the area, first determine what is causing the crack, if possible. If the crack is a structural problem, it must be corrected; otherwise, the crack will simply keep getting larger and larger.

For shallow cracks in concrete, break out all old and crumbling edges from the crack, and, if possible, make the crack about 1 inch deep-if it isn't already. Use a baby sledge hammer and cold or brick chisel for this.

The sides of the crack should be vertical; the hollow will form a sort of key for the patching material. The trick is to create a new area that is wide and deep enough so you don't have to feather out the new cement to a thin edge. Thin edges break.

Remove all dust and debris from the area with a broom. Then flush the surface with clean water. Sweep away the water with a broom, so there is no open, standing water. The area should be damp with water, however. You can buy already-mixed or ready-to-mix concrete patch. Or you can mix your own: 1 part mortar cement to 4 parts sand. Make the mixture "soft" and "mushy."

Fill the crack or cavity with the mixture, using the straight edge of a board to level it. Then let the job set for about 20-30 minutes and finish the surface with a trowel so it matches the surrounding surface. If the patch is in a vertical surface, make the concrete mix thicker.
Note: You can buy special bonding materials that can be brushed onto the area and mixed with the cement to help hold the patch in place.

Shallow holes-
Use the very same technique as above to patch shallow holes in concrete. However, larger surfaces, such as holes, should be roughened first with a cold chisel to help hold the patch in place.

Holes in new concrete walls-
Sometimes you will see holes in newly placed concrete walls. This is due to improper tamping or because aggregates in the mixture have lodged in center spots. For these holes patch according to the steps detailed above.

If, when cleaning out the hole, the hole becomes larger and larger (as it sometimes tends to do), you can punch a hole in the good, firm concrete and drive in a metal pin such as a carriage bolt, and then make the patch. The bolt helps hold the concrete in place. The pin must be 1/2-inch lower than the finished surface.

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