Quck answer
Concrete cracks can occur due to various factors such as temperature changes, moisture, or settling of the ground. To repair cracks in concrete, follow these steps:
1. Clean the crack: Use a wire brush or chisel to remove any loose debris or dirt from the crack. Rinse the area with water and allow it to dry completely.
2. Fill the crack: Use a concrete patching compound or epoxy filler to fill the crack. Apply the filler with a putty knife, ensuring that it is level with the surrounding surface.
3. Smooth the surface: Use a trowel or a damp sponge to smooth the patched area and blend it with the rest of the concrete.
4. Allow it to cure: Follow the manufacturer’s instructions for the curing time of the patching compound. Keep the area protected from foot traffic or heavy loads during this time.
By following these steps, you can effectively repair cracks in concrete and restore the structural integrity of the surface.
Concrete, a durable and ancient building material, is prone to cracking. While cracks themselves may not be a major issue, they can grow and lead to structural failure, especially in colder climates where the freeze/thaw cycle is a concern. However, the good news is that repairing concrete cracks is a simple process that can preserve the integrity of your concrete structures.
Identifying Live Cracks
Cracks in concrete are caused by stress or drainage problems. Internal forces within the concrete result in cracks due to settling or movement, while inadequate drainage can create stress-related cracks. When you find a crack, mark its ends and measure its width at the widest point. If the crack continues to elongate or widen, it is a live crack and requires consultation with an inspector or structural engineer to identify and fix the underlying issue.
Preparing the Concrete for Repair
Image Credit:
Stephen Paul for Hunker
Regardless of whether the crack is on a flat or vertical surface, the repair process is similar. The first step is to remove as much of the failing concrete as possible using a cold chisel and maul. It is important to create a dovetail-shaped keyway around the crack, wider at the base than at the top, to ensure the repair product adheres properly. Avoid using grinders or mechanical tools to preserve as much of the original concrete as possible. After chiseling, use a wire brush to remove debris and clean the area with water or a detergent if needed. Apply a thin coat of latex-based concrete bonding agent to cracks wider than 1/16 inch.
Repairing Large Cracks
For larger cracks, use a cementitious concrete repair mix. These dry powder mixes have small aggregate to fill small and angular spaces, and can be used similarly to bagged concrete mix.
- It is recommended to follow the instructions on the packaging for mixing the repair product. Using a latex bonding agent instead of water is usually a good idea, as it makes the product more flexible and easier to spread. However, some products already have vinyl or latex additive mixed in, so adding bonding agent is not necessary. The latex or polymerized fluid also adds flexibility to the product after it cures.
- Apply the repair mix using a pointing trowel, pressing it firmly into the crack and slightly overfilling it. Wear gloves to protect your skin from the caustic Portland cement in the product.
- Once the mix has set up, use the trowel to smooth the surface and make it level with the surrounding areas. If the concrete structure being repaired has a texture, use a wire brush to blend the repair in. It’s best to do this within an hour of applying the concrete product, before it hardens.
Tip
Cementitious concrete repair products can be painted with any masonry paint or sealer after they have cured, including epoxy-based garage floor paint.
Quick Fixes: How to Repair Small Cracks in Concrete
Image Credit:
Hunker in Partnership With Acme Real Estate
For smaller cracks (less than 1/16 inch wide), you can use a concrete crack repair product in a cartridge. These products are usually polyurethane based, although some newer options use less caustic polymers or even epoxy. Since these products have strong adhesion, it is usually not necessary to create a dovetail-shaped keyway. Simply clean out the crack with a wire brush, rinse it, and apply the product with a caulk gun following the instructions on the package. It’s important to note that while these products are convenient and highly flexible, they cannot be shaped or sanded after application, and not all of them take paint well.
Final Note
Whether you use a dry powder repair mix or a polymerized product from a caulking cartridge, your main goal should be to fix the crack as soon as possible, especially if it is in an exterior environment. After making the repair, monitor the crack to see if it continues to widen or lengthen. If it does, contact a structural engineer for further assistance.
