A Guide on Patching Concrete Walls

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    Though a concrete wall has a long lifespan of around 50 years, that still isn’t immortality. Like any building part, it can break down. Therefore, knowing about patching concrete walls can be an important aspect of homeownership. 

    Read the DIY Guide to learn how to perform this task. 

    patching concrete walls

    What You’ll Need 

    • Newspapers
    • Hair Dryer
    • Thin Waterproof Object (Ruler, knife, etc.)
    • Handheld or Larger Vacuum
    • Wire Brush
    • Hammer and Thin Chisel
    • Ruler or Tape Measure
    • Pencil
    • Epoxy Kit (More Info Below)   
    • Plastic gloves
    • Two cheap/disposable 1/2 teaspoons   
    • Bucket   
    • Trowel

    Step #1: Cover the Floor With Newspaper 

    You’ll be dealing with debris and chemical mixtures. Covering your floor will make the later cleanup easier. 

    Spread newspapers on the floor. At a minimum, these should cover the length of the crack. 

    Step #2: Undercut the Crack 

    Undercutting is a process in construction where a cut is made to help with an installation. In concrete repair, this helps the inner material of a crack bond with the sealant. You can do this by widening the crack with a hammer and chisel.

    Take the hammer and chisel. At a 45 to 90-degree angle, stick the flattened edge into the crack about an inch from the right or left edge. The goal is to keep the hole you’ll make inside the crack. 

    Gently tap the chisel with your hammer. Make a hole that’s about one inch long. Then reverse this and do this for the upper portion of the inner crack.

    Repeat this process down the crack. Make sure the holes are about two inches apart. 

    Step #2: Clean and Dry the Crack 

    Dampness and debris can both interfere with concrete repair. They can stop your epoxy from bonding with the rest of the wall. Therefore, you need to clean and dry the crack before you apply your sealant. 

    Drying the Crack 

    Dry the crack first. You can use a hairdryer to do this. Turn the dryer on and run it back and forth across the crack for a few seconds.

    After this is done, wait fifteen minutes. You can then check the dampness of the crack. Use a thin waterproof object such as a knife or ruler to do this.

    Don’t use paper or cardboard as these can break off and get stuck in the crack. Fingers are also not a good option. Injuring them or getting them stuck in the crack can be a serious problem. 

    If the crack is dry, you can move on to cleaning. 

    If it isn’t dry, it’s likely that water is leaking through the crack. Wait a few hours or a day. It should be dry then. 

    Cleaning the Crack

    Get the vacuum and wire brush. You will use these to remove any debris from the crack. 

    Start using the wire brush at one end of the crack. Push it down, up, or across the crack. Get the bristles into the crack as far as you can. 

    Stop once you’ve reached the other end of the crack. There should be some debris on the floor. 

    Use the vacuum to pull anything left over out of the crack. Clean up what’s on the floor while you’re at it. 

    Step #3: Prepare the Crack

    Before you get an epoxy kit, examine your wall crack. If it is still moving or wider than 1/4 inches, try another method.  

    You should also consider calling a foundation maintenance services expert. They can inspect your crack and make sure dangerous structural damage wasn’t the cause. 

    The epoxy kit used for this example contains the following items.

    • Liquid Concrete Repair (LCR)
    • Seven plastic injection ports
    • A caulk gun
    • A plunger rod
    • A two-part epoxy paste 

    Making Marks

    You inject epoxy into a crack using plastic ports. These should be placed about eight inches apart along a crack. 

    Your first step should be to measure these spaces. Do this with the ruler or tape measure. Then you can make marks at the ends of each space with the pencil. 

    Mixing Two-Part Epoxy Paste

    Put on your gloves. Ideally, you won’t touch the epoxy. However, it’s a good idea to protect your hands. 

    There should be two different containers of epoxy materials. Use a separate, equal-sized teaspoon for each container. You don’t want to contaminate the materials of one container with those of the other.

    Use the teaspoons to measure equal portions of both epoxy parts. You will apply this to your injection ports. Use your best judgment as to the amount that you need. 

    Put the two equal amounts in the bucket. Mix them together until it’s uniformly gray.

    Put the Injection Ports on the Wall

    Find the injection ports. Take the trowel and spread the epoxy mixture along the wider base portion of each one. Do not cover the hole. 

    Place the injection ports on top of your earlier marks. Let them sit for 10-15 minutes. This will allow the epoxy sealer to cure. 

    Cover the Rest of the Crack

    Mix a larger amount of the epoxy paste. Use this to cover the length of the crack with the trowel. The paste should be about 1/8 inch thick. 

    You should also cover the base portions of the ports. Only the neck should be visible. 

    If the other side of the wall is accessible, check it. If you can see the crack there as well, seal it. Don’t worry about injection ports as they’re unnecessary here. 

    Allow the paste to cure for 6-10 hours. Then you can continue with the next step. 

    Mix and Use the Liquid Concrete Repair (LCR)

    Mix another small amount of epoxy paste. 

    Also, mix the LCR in its cartridge with the plunger rod. Then, place this in the caulk gun.

    Start by filling the lowest port. Wait for the LCR to ooze out of a higher port. Seal the lower port with the epoxy paste. 

    Continue up the crack with this process. For the last port, wait for the LCR to stop flowing. Take the caulk gun out and seal up that port.

    Wait around five days to let the LCR cure. You can then remove the injection port necks with a hacksaw or anything handy and sturdy.

    Throw out the teaspoons, gloves, and newspapers. 

    Patching Concrete Walls is Easy With Us

    This process can be easy for some, but it may be hard for others. You might also find that you’ll spend a lot on these kits and mistakes you’ll make. 

    If you’re lost, call us. We offer help with patching concrete walls as well as other home and foundation repair services in Alexandria, Virginia, and Arlington, Clarke, Culpeper, Fairfax, Fauquier, Loudoun, Orange, Prince William, Shenandoah, and Warren Counties.  

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