Repairing existing concrete can be a daunting task, but with the right tools and techniques, you can extend the life of your patio, driveway, or other concrete surfaces. To start, you'll need to wear heavy boots and goggles and clean the surface dirt with a gas pressure washer that can reach at least 3,500 psi. You can then remove old sealant, clean joints, and apply new sealant. For hard-to-remove stains on exterior slabs, use Quikrete's concrete and asphalt cleaner.
Cut the hardened sealant from the expansion joints with a utility knife. If any of the expansion joints are ½ inch or larger, first insert a compressible foam “backup rod” into the joint to prevent the sealant from sinking between the slabs. After cleaning and preparing the joints, squeeze Quikrete's self-leveling polyurethane sealant into each joint with a standard caulking gun. Concrete screed is another way to make old concrete look new again.
A concrete coating is applied over the existing surface, offering a variety of color, texture and pattern options. This type of decorative finish can be done on driveways, patios, pool decks and even interior floors. Once the job is complete, you can do a quick check to see if the bond was successful. Wait at least 24 hours, then gently touch the patch with a hammer or other opaque object and hear a hollow echo. If you only get a dull blow, then the material has adhered well.
If you get a hollow sound, the material has not adhered and will crack over time. In this case, you must start from scratch. You must wait at least 28 days before placing anything on new concrete. If you have several cracks that run so deep that they seem to cut through the slab, a repair would only be temporary. If the slab has so much sand and gravel on the surface that it keeps coming back despite sweeping and dripping, don't waste your time on repairs.
This job is best left to a professional who can assess the condition of your existing concrete and determine the scope of work required to ensure good coating performance and bonding. When using a liquid bonding agent, paint it onto existing concrete and allow it to dry until it is tacky. If repairs are made within an inch, adding acrylic fortifier to quick-setting cement will increase bond strength. However, there are many repair options available that will save you money, conserve resources, and eliminate disposal issues. After the adhesive has become tacky, apply a scrape coat as described above, and then apply the repair material. As long as the steps are structurally sound and don't chip, flake or break completely, you can repair most surface problems.
On a warm day, the existing concrete surface will be warm enough to suck water out of the repair material. The most effective way to ensure that the bonding agent enters existing concrete is to apply it directly with a brush or rag. If you are going to make a large area and it is not practical to apply a scrape coat, you will need to spray the surface with water before applying the repair material. If a sidewalk has risen or fallen at almost every joint, repairing it will not provide a long-term solution. When patching existing concrete, here's how to achieve a strong and durable bond between new and old concrete: First mix additional repair material to the right consistency and apply it over this thin layer for scraping. Then paint adhesive onto existing concrete and allow it to dry until it is tacky.
Finally apply scrape coat as described above and then apply repair material. With these steps in mind, you can easily repair existing concrete surfaces without having to replace them entirely. This will save you money while conserving resources and eliminating disposal issues.