Repairing concrete is not difficult. Preparation is the key to a long lasting repair. Here are the procedures for a couple of the more common problems you might encounter around the home.

Cracks in Sidewalks

Enlarge the crack along its entire length with a cold chisel and hammer. Use gloves and eye protection! Make the crack wider at the bottom than at the top, a process known as undercutting. It helps to bond the new concrete with the older concrete. After the crack has been thoroughly undercut, remove all loose material and brush the area with a wire brush.

The new concrete patch will hold better if a concrete adhesive is used first. This will both assist with bonding and prevent old concrete from absorbing moisture from the newly installed patch. Brush the adhesive into the undercut area and allow it to dry until it becomes tacky.

Use one part Portland cement to 2 1/2 parts of fine, clean sand. Heavier concrete patch jobs call for one part of Portland cement to two parts of sand and three parts of gravel. Building supply centers sell pre-mixed concrete for this type of job. All you add is water and it makes things much easier than buying and mixing the ingredients yourself.

Tamp the concrete patch mix tightly into the undercut area. Be sure to fill all areas completely. When the mixture begins to set, smooth it down with trowel or float. Use a metal trowel for a smooth finish. For a rough surface, use a wood float.

Allow the patch to dry for about two hours, then cover the area completely with plastic sheeting or boards. This will prevent the patch from drying too fast, which would weaken the repair. Keep the area covered for about five days. Lift the cover once each day and lightly dampen the repair.

Cracks in Driveways

Concrete driveway repair is basically the same procedure as sidewalk repair. However, the repaired area must withstand much greater pressure. Driveways also tend to be thicker than sidewalks so it will take longer to prepare the area.

Thoroughly clean and undercut the crack, to a greater depth and considerably wider than when repairing a sidewalk. This will take a lot of time on thick driveways. Don’t forget your gloves and eye protection!

Brush concrete adhesive into the undercut area and allow it to dry until it becomes tacky. This is a must on driveway repairs. You need as much strength as possible to support the heavy loads.

Use a gravel mix, rather than a sand mix, for repairing concrete driveways. This mix is one part Portland cement, two parts sand and three parts gravel. Again, there are ready-mix products available that make this part of the task much easier.

Tamp the concrete patch mix tightly into the undercut area. Be sure to fill all areas completely. When the mixture begins to set, smooth it down with trowel or float. Use a metal trowel for a smooth finish. For a rough surface, use a wood float.

Allow the patch to dry for about two hours, then cover the area completely with plastic sheeting or boards. This will prevent the patch from drying too fast, which would weaken the repair. Keep the area covered for about five days. Lift the cover once each day and lightly dampen the repair.

Do not drive an automobile over the patched area for at least seven days. This gives the newly patched section time to dry thoroughly before it must carry the heavy load of an automobile or truck.