Repair cracked concrete in a jiffy
Q: Can you tell me the best way of sealing a crack in my concrete driveway? The crack extends the entire width of the driveway (which is about 9- 1/2 feet wide) in a zigzag pattern. In three places, the crack is about 5 inches long and about 1 inch deep. The rest of the crack is about ¼ inch wide or less and 1/4 inch deep or less. What is the best way to repair it, and what material do I use? Is the ready-made stuff that comes in a tube OK? — Ron, via e-mail
A: Concrete caulk (the ready-made stuff in a tube) is a good stopgap measure, but it is temporary at best. A better repair can be made by reserving a warm, dry afternoon and heading for the nearest home-improvement store for the following materials.
Purchase a wire brush (or a wire-wheel attachment for your power drill), a cold chisel and hand maul, a trowel and a cheap paintbrush. Then pick up enough vinyl-reinforced patching compound to fill the smaller parts of the crack, and a bottle of concrete bonding adhesive. For the larger cracks, you will likely need to use sand-mix concrete, plus some additional sand. If you’re not sure about the amount, ask a sales representative in the concrete/mortar section; he or she will recommend just what you need for the repair.
Begin the repair by brushing away all loose debris, dirt and other material from the crack, using the wire brush. Then, take the cold chisel and carefully chisel out the larger parts of the crack, creating a backward-angled cut (one that is wider at the base than at the surface) on each side. Cracks that are 1/4 inch wide or less usually don’t need chiseling. Brush the area again.
Tackle the smaller cracks with vinyl-reinforced patching compound, working in sections. Brush the cracks first with a thin layer of bonding adhesive, then trowel the compound in and feather it out on the surface.
The three larger cracks should be filled with sand to about 1/2 inch from the surface. Then, prepare the sand-mix concrete (mix small amounts by hand) according to directions and trowel into the crack, feathering it even with the surface. Allow the patches to dry and set for at least 24-48 hours before driving or walking on them. Cover with plastic if it rains during this time.