Weather, vegetation growth, and time can cause wear and cracking to occur to your concrete sidewalk. Here are some instructions to help you repair and patch varying degrees of concrete damage in your sidewalk.
Patch Cracks and Resurface
When cracks occur in your concrete you can patch them with a concrete resurface mixture. Prepare the concrete first by cleaning its surface and the cracks thoroughly with a pressure washer to remove dirt, mold, and other debris. It is recommended to spray on a concrete cleaner as you clean the surface, which also helps the concrete adhere.
Mix up your concrete resurface mixture and before your concrete surface dries from the cleaning, press it into the cracks with your trowel, leveling it with the surrounding surfaces. Make sure you allow it to cure properly before walking or driving upon its surface.
Repair Ground Heaving Damage
When the soil below your concrete sidewalk is pushed upwards, it will cause the sidewalk on top of it to also shift upward, usually cracking or separating the sections of concrete. This can create a lip where one concrete section is higher than the other.
Upward heaving can occur slowly when you have a large tree in your yard growing with its root system slowly pushing the concrete upward. Heaving can also occur if you live in a northern climate that has freezing occurring to the soil below the concrete. When the soil contains moisture and freezes, it expands upwards and pushes the concrete upward, as well.
To be able to repair the ground-heaved concrete, it depends on the height of the upward shifting. Concrete sidewalk slabs are usually four inches thick, so if the concrete is pushed upward less than two inches, or half the width of the concrete, you can repair it without removing the slab. Use a grinder to smooth off the raised portion of the concrete to make it level with the surrounding section.
When your concrete has shifted upward from ground heaving and the concrete section of your sidewalk is pushed beyond the surrounding sections, you will need to remove the concrete and re-level the soil to replace it with a new slab. Breaking apart the concrete with a sledgehammer or a jackhammer is the best option to make the concrete more manageable to remove. You can also hire a concrete contractor to demo the slab and replace it with new.
Remove the excess soil and add a base layer of crushed gravel to create a level foundation for the concrete. This gravel also helps drainage below your new concrete to prevent further heaving due to freezing in the soil. Set the forms for the new slab and you can prepare and pour the new concrete. For more information, contact companies like E & H Concrete.