Concrete is an extremely hard and durable surface. While this makes it an extremely valuable building material for foundations, patios, driveways and multiple other surfaces, this also means that it is prone to cracks and minor damage.
However, most cracking is not indicative of serious problems. It is important to know what type of cracks is problematic and which ones are simply aesthetic issues. Thankfully, you can repair minor concrete cracks expeditiously.
Why concrete cracks
Concrete may crack for any number of reasons. The durable material does not contain any elasticity that can handle slight movement over time. Therefore, as the concrete and surrounding surfaces settle, such as houses naturally do, cracks may appear.
Also, fine cracks may appear as concrete dries out during the initial curing period. This is more likely if the concrete has been laid over a large area without any joints that allow room for the concrete to contract. Similarly, concrete can crack due to weather, specifically as the temperature varies and moisture seeps into the material.
When to repair a crack yourself
A general rule of thumb is that if a crack is 1/8 inch or less, does not include any vertical displacement (i.e. the concrete on either side has shifted higher or lower), and is not causing a leak, then it does not need to be addressed.
If the crack slowly grows larger or the concrete is chipping on the sides of the crack, then you may want to repair the crack yourself. Also, if you are planning on staining or painting the surface, it is generally a good idea to repair a crack of any size with a cement-based product.
When to call a professional
If you notice a new crack that has suddenly become 1/4 inch wide or greater, or you notice that there is vertical displacement around the area, this may signify a bigger issue. For concrete surfaces that support a building or areas that you do not want to chance being compromised, you should consider contacting a concrete contractor for professional repair. A large crack can signal that the concrete is no longer structurally sound and requires immediate action.
Repairing Minor Cracks
Whenever possible, perform any repairs to concrete during dry, warm but not hot weather, which will ensure that the repair material will properly cure and adhere to the surrounding cement. If you choose to repair a minor crack in cement yourself, it is important to properly prepare the area.
Get rid of any cement that may have chipped or is loose. Clean away all dust and grime using a stiff brush and a wet cloth, if needed. Thoroughly rinse the area with water, and then allow the cement to dry entirely.
Use a repair material made specifically for concrete cracks to ensure maximum adherence and durability. Premixed cement, concrete crack filler or an epoxy crack filler are popular choices. Fill the crack using a caulking tube or by applying the filler directly. Push the filler into the crack using a small putty knife, applying more material as required. Once the entire crack has been filled, smooth the filler over the surface with your finger or a flat trowel. If necessary, you can wipe the repair with a smooth towel or brush after the filler has begun to harden to blend it into the concrete surface, taking care not to remove material from the crack. Once it has dried entirely, seal the repaired area to ensure it is watertight.