How to Repair a Concrete Driveway or Sidewalk
Since concrete curing is a continual process, concrete surfaces will inevitably begin to crack and disintegrate in certain areas. This is especially true in high-traffic areas that bear significant amounts of weight, like driveways and sidewalks. Fortunately, concrete repair is a fairly easy task if done correctly.
Supplies and Equipment
For this type of job you will need a wheelbarrow, a hoe, a shovel and a concrete trowel, all of which are available at most hardware stores. To actually fill in the damaged area, you will need one or more bags of concrete mix; a single 80 lb. bag of mix will only fill in about two-thirds of a cubic foot, so buy more bags than you think you will need. You will need a hose or other source of water to mix into the concrete. Finally, if the area you are patching is wider than 12 inches, you will also need rebar to reinforce the concrete.
Next, dig out the area to be repaired about four inches deep, removing any loose dirt, gravel and old, broken concrete. Set the rebar in the hole evenly spaced about ten inches apart, elevated about one inch off the ground with small stones or wire. Rebar is essential to preventing larger patches from cracking, as it gives the concrete something to lock into, rather than merely lying on the ground. Before pouring, soak all surfaces that will come in contact with the concrete with water.
After you finish preparing the damaged area, pour the concrete mix into the wheelbarrow and add about one and a half gallons of water per bag. If you have a large repair job, you may need to mix the concrete a little at a time to prevent overfilling the wheelbarrow, since this makes the concrete very difficult to mix. Using a hoe or shovel, stir the concrete until it is wet and moldable, adding more water if required to reach the desired consistency. A thinner mix will take slightly longer to harden, allowing you more time to work with it.
Once the concrete is mixed, pour it into the damaged area, then use the concrete trowel to smooth it and even it with the driveway or sidewalk. Continue mixing and pouring until the entire damaged area is filled.
If you are pouring in temperatures above approximately 80 degrees, be sure to regularly spray water on the surface of the new concrete to prevent it from drying too fast, which can cause it to crack. Although cold temperatures will not directly damage your concrete, frozen ground will. Never pour concrete on a frozen surface; when it thaws, it will crack the concrete.
After the concrete is poured, cover it with tarps or sheets for approximately one week to allow it to cure gradually, without cracking. After that time period, your concrete is ready for use.