Spalling concrete often looks like an oval or round depressions appearing along concrete joints or surfaces. It is a problem that is commonly associated with cold environments. The problem occurs when you apply de-icing chemicals on the concrete surface. It could also be caused by the freeze-thaw cycles.
What Causes Spalling Concrete, And How Can You Avoid It?
Spalls are likely to appear when the rebar becomes exposed. An exposure of the rebar means that water and humidity will find their way into the concrete, causing the rebar to begin rusting.
Rebar exposure could also be occasioned a poor or improper build process. Weather changes will cause your concrete to start expanding, and this will lead to more spalling. You can expect further deterioration to occur.
An important aspect that can assist in ensuring that your concrete will not spall will be to apply a good sealant once the surface is complete. The sealant will ensure that water does not find its way into this concrete.
Proper concrete management helps in preventing concrete spalls. Following the right concrete pouring techniques also prevents this from occurring.
A great way to make sure that concrete will not spall will be to provide adequate concrete cover to the rebar. Joints must also be placed at the right distances, and at the correct locations. A contributory factor to consider will be the concrete mix. Failure to check the water content in the combination could also trigger spalling.
You, therefore, need to pay attention to any exposed concrete edges. Make sure also to provide an adequate cover as specified by the ACI or structural engineer.
Concrete Repair Practices
Depending on the harshness of the condition, your only solution may more or less involve conducting some labor demanding repairs.
- If the real damage is shallower than a third of its total thickness, you should go ahead with the repairs. But if the damage is more than a third of its overall thickness, consider performing a full restoration, or installing some steel bars.
- When dealing with exposed and corroded rebars, start by cleaning the rebar before you can begin the restoration process. A wire brush should be used when cleaning the steel bars. Once clean, a protective coating should be applied to ensure that this does not happen again.
- A cementitious overlay should be applied when this problem is over a horizontal surface like a sidewalk or plaza, or when dealing with a driveway. Once the overlay is entirely set, a waterproofing membrane must then be applied. The membrane will prevent future spalling.
- Effective repairs call for at least 1.5 inches of solid depth be removed. All debris should be removed and thoroughly cleaned before repairs can proceed any further.
- Any patching being done should extend the spalled concrete area by more than four inches.
- Depending on the type of concrete being repaired, use a saw to cut a rectangular region of the affected region. It will allow for concrete and patching to be contained in that specific region.
- You should check whether the old surface is rough or not. A rough surface is ideal for repairs as it provides a better bonding surface for the new concrete being installed.
- You should remove all the fine particles and debris from your concrete before patching can be performed. If necessary, you should use water to clean the particles, before using a sponge to remove the excess water. Always make sure that the surface is completely dry before you can patch or apply any compound.
- Materials to be used when conducting the repairs should be carefully considered. Go for epoxy or Portland cement-based materials for your repairs.
- Mix the patching materials keeping in mind that the compounds can react or dry at a fast rate. Therefore, anything that is being used should be mixed or prepared within a span of fifteen minutes.
- Confirm that your air temperature is well above forty degrees Fahrenheit. This is necessary if you want the patching material to work as it should.
- Any joints that are in need of repairs should be properly restored to allow for concrete slab expansion.
You need access to the best materials when repairing spalled concrete. Apart from applying the rust inhibitor over your steel rebar, make sure to source for materials from renowned manufacturers. Quality supplies are needed to prevent a recurrence.
