Repairing Cracked or Broken Concrete

In reality, a slab of concrete is pretty much a big grey rock. When you turn it into a foundation for a shed or a sidewalk, it becomes much more than that. It’s become something you look at everyday. When a sidewalk or slab crack, either from soil settling beneath the concrete or due to rain, snow, ice and sunlight, it not only becomes ugly, it can also be a dangerous thing to trip on.

So how do you fix that crack in your sidewalk without tearing up the whole thing and re-pouring it? Sometimes you can’t and a section of it does require replacement, this article will help you along the process of deciding if it needs just a quick fix, or a whole new section of concrete.

If the crack in your concrete slab or side walk is small and not from one end of the pour to the other, then it is probably just a tension crack and can be mended before it gets any worse. Concrete when poured, is guaranteed to do three things. Get hard, turn grey, and crack.

So to fix a small crack you will need a hammer or maul and a cold chisel. You will need to get some vinyl patching compound which you can get from most home improvement stores. Simply chisel the crack with the cold chisel and hammer. Make sure you have some safety glasses and gloves on when doing this. To make the new vinyl compound adhere to the crack, you need to under cut the crack. That means making the bottom of the crack, wider than at the top. Place the cold chisel on an angle to do this.

Sweep the crack clean of and debris when you are done chiseling. You can use an old paint brush to clean the crack. If you have access to an air gun and air compressor, than this will work even better. Clean the crack as good as you can. Fill the bottom of the crack with some sand. This helps to prevent the crack from returning through the newly applied vinyl patching compound. Simply fill the crack now with the vinyl patching compound using a trowel or drywall knife.

If the crack is a larger one and continues from one side of your concrete pour to the other, than the problem is probably settling. You will need to remove a large piece of concrete and bring the under surface up to it original height.

To do this you will need a large sledgehammer. If the areas real large such as a section of driveway, then renting a jackhammer may be the right tool for the job. Break up the damaged section into small pieces fro easier removal and hauling away. If necessary, you may need to create a form. Use a product that is a 2 by something (2×4, 2×6, etc.) Drive stakes on the outside of the form to hold it into place.

Pour either a thin layer of gravel or sand into the area where the concrete was removed. Use a hand tamper to tamp the under surface. Do this for a while, and then spray a little water on it and wait until it soaks in, add some more gravel or sand and tamp again. Repeat this step until you have reached the depth of the original level of under soil.

Lay a small piece of wire mesh into the hole and using a few of the pieces of concrete you broke off earlier, place under the mesh. This way concrete will flow underneath of the mesh. Coat the old concrete with a bonding agent you would buy from your local home improvement center. Mix the new concrete into a wheelbarrow or bucket and pour into the hole. Using a 2×4, screed the top of the newly poured concrete to match the surface of the old concrete. Float and finish the new concrete to match the surface of the old.

That’s it! Use this method on small or medium sized cracks, and definitely don’t use this on an area that is load bearing. Enjoy your newly fixed concrete!