When the time comes to repair concrete, you need to have a sound understanding of exactly how to patch it since it will not only save you time but also save you a great deal of money and effort.
Read on for information on repairing small cracks, sidewalks, and driveways, as well as patching holes and corners.
Repairing Hairline Cracks
Mix water with basic Portland cement to repair hairline cracks. Moisten the old concrete along the hairline crack with water for several hours before adding the grout. Moisten the original concrete, but do not use so much water that it accumulates on the surface.
Use a trowel to apply the mixture. Fill the cracks and scrape the surface to make it smooth. Cover the patch with plastic and leave your work to dry for several hours. Moisten the patch once a day for five days, leaving it covered at all other times. After five days, your patch should be done curing and therefore fine to leave uncovered and dry.
Repairing Sidewalk Cracks
Ironically, if a crack is larger than a simple hairline, it will have to be enlarged with a hammer and chisel before actual repairs can be made. As you chip the crack, do so in a manner that widens the bottom more than the top in order to create a better bond between the patch and the original slab.
You must chisel the crack until it is 1 inch deep and free of all debris. Spray it with a hose to make sure all of the dirt and loose particles have been removed, then scrub it.
Next, apply a concrete adhesive to the surface using a paintbrush. Allow it to dry slightly so that it has a sticky texture. Once you have a good, sticky surface for the concrete, simply add water to premixed concrete and patch the crack. For small patching jobs, use a pre-mixed concrete patch. If you use a ready-mix concrete patch, all you need to add is water.
Fill the crack completely and tamp the patch. As the concrete settles, scrape the surface with a trowel. You can create a smooth surface with a metal trowel. Switch the trowel for a wood float to make a rough surface.
Allow your work to dry for several hours, then cover the patch with plastic. Moisten the area once a day for five days, keeping the surface covered at all other times.
Repairing Concrete Driveways
The process for repairing driveway cracks is similar to that of sidewalk cracks, but the repair for a driveway must be able to withstand more weight than a sidewalk. This means you want to use gravel in place of sand for your mixture.
Just as with sidewalk repairs, you must chisel, clean, and apply adhesive to the hollowed crack. You must chisel deeper than you did for the sidewalk in order to make the strongest repair possible. Repeat the same steps for applying the concrete as you would for a sidewalk.
Don't drive over the new repairs and keep other heavy loads clear while the concrete settles over the course of about five days or you'll risk damaging the repair.
Repairing Cracks and Holes in Concrete Walls
Fixing a cracked concrete wall is similar to repairing a cracked sidewalk or driveway. You follow the same preparation process to chisel, clean, and apply adhesive. The dimensions you carve are dependent upon the size of the crack.
While you scrub the excavated crack, make sure not to sand the surface too smoothly. Over sanding will create a weaker bond between the old and new concrete.
Applying an adhesive is the most effective method, but if you do skip this step, be sure to at least moisten the area.
If the cracks are on the smaller side, use premixed cement for the patch. Fully fill the crack with the mix and scrape the edges with the trowel the crate a smooth surface. As the concrete dries, use either brooms or brushes to duplicate the pattern on the original wall. If the wall has a hole, repair it the same way.
Patching Holes in Walks or Driveways
Sidewalk and driveway patch jobs vary depending on the depth and the size of the hole. If the hole is extremely deep and large, you must undercut it as previously described and fill the area with a gravel mix.
When flat surface areas have holes that are not as large, you can forego chiseling and fix them with latex cement. Just clean them thoroughly with a wire brush, then a smaller brush, and finally hose the area, before applying the patch.
Latex cement is typically retailed in 5-pound cans. The cans contain a smaller can of liquid latex that you mix with the latex cement in the larger can to make a paste, which you add to the area in 1/4-inch layers. Smooth each layer and wait until it starts to dry before you add the next layer. Use either a wood float or a trowel to finish the final surface.
Repairing Broken Concrete Corners
When dealing with broken concrete corners, simply use either latex or epoxy cement to rebuild the damaged area. As always, clean and moisten the area to be repaired as your first step.
Slowly rebuild the damaged surface by applying 1/4-inch layers. For large swaths of damage, construct a frame to hold the layers in place while they dry.
Information in this article has been furnished by the National Retail Hardware Association (NRHA) and associated contributors.