Do I Need Concrete Wall Repair, and What is the Best Way To Fix It?
Repairing cracks in a concrete wall can take lots of time and experience. Its a procedure that can usually be completed within a day to one week, depending on how big the crack is. It could be caused by water problems and not having the correct water control causing pressure to push on the wall. Cracks that form in a concrete wall, particularly a basement wall due to sinking and soil settlement, water, frost heave or ground movement can be either structural or non-structural in the building. Sometimes you can't see the damage going on behind the wall until it is to late. The methods discussed in this article can be used to repair minor, non-structural cracks.
Clean and Prepare the Cracked Area for Concrete Wall Repair
To prepare the surface, use any combination of wire brush, vacuum or power washer to remove any oil, dirt or debris from the concrete wall surface and from inside the crack because we want to see and explore what is causing the problem. You will need to drill holes in the wall to see if they are holding water called weep holes. Do not use any sealant to the crack surfaces as this will only cause more pressure build up and cracks in other parts of the wall. When you enlarge the crack using a concrete chisel and a hammer to put epoxy in it, it can cause more damage.
Concrete Patching- does it work?
Lots of products are available that can be used to repair the crack including premixed concrete. KEEP in mind that this will only get worse if stress cracks are inside that you can't see. If you are using concrete to “patch” the crack, apply masonry adhesive or some type of bonding agent to the inner surface of the crack only after you have fixed the problem causing the crack. This is where you need to do some soil testing or excavating to find out what is going on. If we find the problem, then you can fix the issue and then trowel the new concrete into the crack until it is completely filled; don’t leave a depression along the surface of the patch. Use a trowel, float, brush or broom to match the texture of the adjacent concrete finish.
Manufactured Sealants- Are they any good?
Most are not when trying to do concrete wall repair. They are simply a band aid. Other types of commercial sealants work well for filling cracks if you take care of the hydro static pressure behind the wall. This is very important to do. Epoxy products can be used to fill cracks up to ½ inch wide, but will not bond to wet or “green” concrete. Epoxy is typically purchased as 2 separate compounds that are mixed together at the proper ratio. It creates a semi-rigid bond with strength properties greater than the concrete itself. Consult the manufacturer’s instructions on the proper procedure for mixing, applying and curing the epoxy. Epoxy-based grouts are an option if no further expansion of the crack is expected. The material provides a rigid bond that will not accommodate additional movement within the concrete.
Expandable polyurethane is a water-resistant foam sealant that also can be used to fill cracks up to 3/4 inch wide. This fix can cause problems if water behind the wall comes through the area over time. There has to have no water issues. The polyurethane creates a flexible bond that will allow for minor shifts and ground movements. Polyurethane is injected under high pressure so that entire cavity is sure to be filled.
Generally speaking hydraulic cement and caulking are not recommended for repairing cracks in concrete. Hydraulic cement is a rigid material that will not bond well to concrete. Caulking is flexible but does not provide a permanent bond. Neither is impervious to water.
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