Trowel the compound into the cracks using a small putty knife. Smooth the surface right away, while the compound is still moist, because concrete compounds typically begin to set very quickly. Allow your repair work to dry thoroughly before you let anyone walk or drive on the surface.
The beginning steps for repairing larger cracks in concrete are the same as for small cracks, but larger ones require the use of more advanced techniques: caulking or sand packing. Use a screwdriver to chip away any flakes or loose concrete.
Scour the cracks with a wire brush, and rinse them out using a hose or a bucket of water. To employ the caulking method, get some siliconized latex concrete caulk, which is available at most hardware stores. Using a caulking gun, force the caulk deep into the cracks along their length and breadth. The caulk will expand to fill the crack, and the nature of the substance will allow for expansion and contraction during weather changes, cutting down on the frequency of future repairs.
The caulking compound will self-level, so there is no need to smooth the surface, but for large cracks, multiple applications may be needed. If you choose to use the sand-packing method, you will need to buy sand and concrete patching compound, preferably with a latex additive for flexibility. Pour in a layer of sand to help fill the cracks, then apply the patching compound on top of it with a trowel.
Smooth the surface quickly, and feather the new surface into the existing edges for a finished look. For serious or exceptionally large concrete crack repairs, you might need to call in a professional. This will help ensure that the patching material used will not pop out of the crack when the concrete expands and contracts. Overfill the crack slightly to compensate for the slight shrinkage the grout will experience as it dries.
If you'll be using vinyl concrete patch material, be sure to follow directions and only mix as much as you can use within the specified time, which is usually less than 20 minutes.
Begin by wetting the crack with a spray bottle or hose. Vinyl concrete patch material shrinks as it dries so applying it in layers will allow you distribute a more equal distribution that is less likely to crack. Once your initial layer has had enough time to dry per package instructions -- usually a couple of hours , proceed with additional applications until the crack is full.
If you choose to use textured caulk, keep in mind it has to be applied to a dry surface. In addition to completely filling the crack, apply some overfill to account for shrinkage as the caulk dries. As you're finishing applications, use a pointing trowel to blend the final patch material with the surrounding concrete to form a good seal of the crack. Once you are done filling the crack, use a small brush, broom or even a block of wood to rub across your patch to help match the consistency of your patch surface with the surface of the original concrete.
If the concrete cracks continue to reappear, call in a professional to rule out any larger problems. Search for:. Concrete cracks for several different reasons, the most common reasons for a basement floor to crack are; shrinkage, heaving and settling, premature drying, and expansion.
Concrete is primarily made up of cement often in powder form , an aggregate like rock or gravel, and water. The moisture is lost as the concrete hardens, but since the water is what enables the concrete to take up more space, the concrete will shrink.
While shrinking, more and more stress is put on the concrete, especially when hardening at corners or around cylindrical objects and circular spaces.
Eventually, the concrete cracks to relieve all the tension put on by shrinking. Shrinkage is a common problem when installing concrete during the hot summers, where the moisture is lost quickly, and when concretes mixed with too much water. When a concrete mix contains an excessive amount of water, the concrete becomes a lot smaller once it hardens after all that waters lost through evaporation. However, these types of cracks should still be repaired and sealed to prevent water and small insects from seeping in.
Heaving occurs when the soil beneath the concrete floor expands and pushes upward. After periods of heavy rainfall or snowfall, the soil will absorb the groundwater and can heave, or lift, the concrete floor by as much as a few inches. When the water in the ground dries up, the soil will settle again.
Tree roots are another common cause for heaving, often seen in sidewalks and driveways. As tree roots grow underneath the surface, they could cause upward pressure against the concrete and cause it to crack. Conversely, if a tree is removed, taking the roots with it, there will be a space underneath the concrete that will cause it to crack due to the uneven ground underneath it, not supporting its weight properly.
This cracking due to space in the soil also happens when a tree decomposes. Aside from the c visible cracks, if your home is settling unevenly you might also notice the following issues around the house:. Cracks caused by heaving is a sign of a more serious problem that should be taken care of by a professional foundation contractor.
In some cases, the entire basement concrete floor will need removed and re-poured. If moisture is the problem, an interior drain beneath the floor might be needed to collect future groundwater.
This type of thing could end up costing the homeowner ten of thousands of dollars. Keep in mind, not all heaving problems will require a complete replacement of the basement floor, but this is something that a professional should evaluate and determine for you. Call at least three different reputable foundation contractors in your area to get their opinion and quote.
There are two types of cracks that are brought on by premature drying, Crazing cracks, and Crusting cracks. Crazing cracks are thin hairline cracks that resemble a spider web or a shattered piece of glass. These types of cracks are brought on when the top layer of the concrete slabs loses moisture too quickly. Although not pleasant to look at, they do not pose any structural concerns for the home.
First off, you will need either a jackhammer or a sledgehammer to pound out any old concrete. Be sure to remove all sections that have cracks in them. If those sections are fairly small, you can also use an angle grinder. Then, as discussed in the first section on preparing the crack, you also want to remove as much debris as possible.
Now, you will need to measure the space which you are looking to fill with concrete. Once you know what the volume of the space is, you can then make your calculations for how much concrete you need to buy. Using a bucket or wheelbarrow, some water, and a mixing tool, mix the concrete and get it to the right consistency. Pour the concrete into the space as required, and then use a concrete trowel to flatten and smoothen the surface.
Let it dry, cure, and harden as indicated on the label of the specific concrete you have. Which method you go with will depend on the size and severity of the crack, as well as how far you are willing to go to repair it. In any case, though, make sure to do the right preparation work before you begin fixing the crack.
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