Patching & Repairing Concrete
By Monte Burch
First-aid for Concrete Construction.
Concrete is one of mankind’s greatest inventions. Very durable, it can also be aesthetically pleasing. Concrete is also often a major building material in and around homes. Over time, however, concrete can deteriorate. Patching and repairing concrete can be easy or difficult, depending on the project and the amount of deterioration. Most repair projects are fairly simple using some of the specially formulated patch and repair products available these days.
Concrete is basically made by mixing together four ingredients, Portland cement, sand, crushed stone or gravel and water. These ingredients must be mixed in the proper proportions. You can mix the ingredients yourself, or purchase premixed products, blended for specific chores.
Specialty concretes are very user friendly, and have distinct characteristics such as fast initial or final setting times, high early or final strength, or increased resistance to cracking and chipping. It’s important to choose the correct specialty concrete product for the specific job. Regardless of the product chosen, it’s also extremely important to follow the instructions and safety precautions on the package.
You’ll need a few tools, including a cold chisel, ball-peen hammer or 8-pound sledge for larger areas, protective goggles and gloves. A brush and broom or hand vac is also necessary, as is a plasterer’s trowel and pointing trowel. If you’re resurfacing steps and slabs, you’ll need an edger as well. You may also need lumber for forming some repairs. And, of course, you‘ll need the appropriate repair product. From the Quikrete Company this includes Concrete Bonding Adhesive, Acrylic Fortifier or Vinyl Concrete Patcher or packaged concrete. For interior floors you’ll need Self-Leveling Floor Resurfacer.
It’s extremely important to prepare the repair area properly before applying the concrete product. Remove all cracked and crumbling areas. On small areas you can do this with the point of a heavy-duty trowel. For larger areas use a sledge and cold chisel to break away any thin or loose edges. Then sweep, vacuum or hose away all dirt and debris down to a solid base.
To patch the crack shown in this article, we used Quikrete Vinyl Concrete Patcher, a self-bonding cement mix made specifically for repairing broken, chipped or loose concrete and masonry, as well as filling medium to large cracks. The cracks shouldn’t be deeper than 2 inches. The material is available in tubs or a 40-pound bag. It will adhere to all properly cleaned surfaces and can be troweled to a feather edge of 1/16 inch. All you need to do is add water.
Again, the first step is to properly prepare the surface. Use a chisel to remove all cracked and crumbling materials, squaring off the edges. Even better yet, undercut the edges using the chisel and hammer. Use a wire brush to remove any crumbling materials and to roughen the surface if it is finished smooth. The material should not be applied over painted surfaces. Clean away all debris, and then further clean with Quikrete Concrete and Asphalt Cleaner. Rinse with water. Mix only the amount of material that can be applied in 30 minutes, according to the manufacturer’s instructions. By design, Vinyl Concrete Patcher is a “stiff mix.” It is best to keep the trowel clean and dry while applying the mix. This prevents the mix from curing on the tools.
Before application dampen the area with clean water, but remove any standing water. Apply the mix with a trowel, using heavy trowel pressure to force the mixture into the crack. Overfill slightly and then trowel smooth to match the surrounding concrete. If cracks are deep it may be necessary to apply in 1/4-inch deep layers. Allow the material to dry for two hours between layers. Clean the tools immediately with water.
Small cracks are easy to patch with Quikrete Gray Self-Leveling Concrete Crack Seal. The product comes in a squeeze tube, and fills and seals cracks in concrete up to 1/2-inch wide. For large or deep cracks, you can use Quikrete Sand Mix or the company’s Concrete Bonding Adhesive.