my Old Workshop

How to repair concrete (Part II)

Last time, we looked at materials and helped you decide how to tackle your concrete repair. Let’s get down to patching that damaged area.

Remove any loose or crumbling sections of concrete, and brush the area firmly with a steel brush. If the surrounding area appears loose, tap it lightly with a mini-sledge to test its soundness. If you’re patching a hole, enlarge it so that it’s at least an inch deep. By etching the old concrete with diluted muriatic acid, you’ll ensure a better bond.

Wet the area with water, but don’t leave standing water. A liquid bonding agent also helps ensure the new concrete’s going to stick.

Mix up your concrete and pour it into the hole. Tamp it firmly with a trowel, pressing it hard against the existing concrete to ensure a good bond and no air bubbles. The concrete will shrink, so mound it slightly, and finish it off smoothly.

If you’re fixing a damaged step, you can make a form by positioning a 2×8 against the riser, holding it in place with a few bricks. Because this area is under more stress than a flat patch, you might want to drive a couple masonry screws into the old concrete before adding the patch. This will help hold the patch in place.

The additional Portland in the mix means the concrete is going to dry faster, so you need to be extra careful about curing the concrete for maximum strength.

Cover the repairs with plastic sheeting, and spray it daily for about a week.