Why Concrete Fails and How to Fix It

Posted on: 22 June 2016


Concrete will almost always eventually crack, chip, or otherwise get damaged and need repairs. This is because the material is porous and may absorb water, salt, chemicals, and other damaging elements, and it's also often neglected over the years, with building owners or property owners failing to add a coat of protective sealant as needed. If you have a concrete surface that is cracked, flaked, broken, or otherwise needs attention, note a few reasons why it may have failed and what might need to be done to fix it.

Broken in several chunks

Concrete often has rebar or another metal reinforcement added to it as it's poured, to keep it in place and keep it strong. However, that metal material can corrode, rust, or otherwise get damaged if water, salt, and other chemicals seep into the concrete and reach that metal. In turn, the metal is no longer able to support the concrete and it may break in chunks where the metal is most damaged. This type of damage to the rebar can also cause spalling or cracking along the surface, something often called concrete cancer, as this damage will continue to spread if left untreated.

In these cases, you will probably need to pull up the old concrete along with the damaged metal reinforcements and replace it all. Be sure you're sealing the concrete as recommended so your new metal doesn't get corroded.

Broken in two; one side is lower than the other

When concrete breaks in two, with one side sunk lower than the other, this usually means the ground underneath it is soft and can no longer support the concrete. This often happens with soil that is too moist; it becomes soft so that the weight of the concrete sinks in one area and the concrete breaks in two. You may need to add treatment to the soil to make it firmer and stronger, and slab jack the concrete; this refers to adding lime or another substance under the concrete that pushes it back into place. The crack can then be repaired with a filler.

Cracking, peeling

Cracking and peeling of a concrete surface is often the result of salt and other chemical corrosion on the surface of the concrete. This can also result from the concrete expanding as it absorbs moisture. You may need to have the concrete grinded, meaning the surface roughed up like how damaged wood is sanded, so it can be repainted or otherwise treated. Be sure to add sealant as needed to protect it from this recurring damage.