Concrete Cracks
/Lets explore this topic.
In our time in business, we have seen more cracks than some could ever count. We have seen cracks that are large, some that are small, some that are wide and some that are long.
Most concrete in its hardened state is a very brittle structure. It has very low tensile strength. Tensile strength measures the concrete’s ability to flex without cracking. However, most concrete also has a very high compressive strength. Compressive strength is the amount of force that can be applied to the surface of the concrete before it becomes pulverized.
This combination of almost opposite attributes often leaves people stunned that such a “hard” object could possibly crack.
In the midwest, particularly Indiana, we get extreme fluctuations in temperature and weather elements that make the ground literally move during different times of the year.
As the ground freezes and expands in the winter (sometimes 36” deep) it naturally pushes concrete slabs (that do not have a foundation) up and around. This massive upward pressure can create a tendency for concrete to crack as it reaches its maximum tensile strength limit.
Cracking can also happen due to shrinkage. Shrinkage cracks usually occurs during nicer times of the year and is caused by moisture content from the concrete evaporating and creating a naturally occuring “shrinkage” effect. This shrinkage can force the concrete to separate from itself forming usually minor hairline cracks, sometimes even within hours, days, or weeks of installation.
Cracks can form in OR outside of designated control joint lines. Control joints should be placed 10’ in each direction to try to avoid sporadic cracking (cracking that juts outside of a control joint) or random cracking. Although random cracking occurs on a semi-regular basis, your contractor hates it just as much as you do.
Lets talk “repairs”…
”Repair” is a tough word to use. Concrete cracks can be “treated” but repair isn’t quite the right term. Treatment can range from caulking it to simply applying sealer. Some treatments can get more convoluted and in depth but we believe a crack should always be left aline as long as possible, especially if cosmetics are important. Generally, if a crack has not reached 1/4” in width (opening width) usually if you can stick a pencil into the crack, its time for a treatment.
Treatment of a crack that has reached a width of 1/4” is solely to provide waterproofing. Caulk is usually the go-to material for flexibility and durability however it can be very ugly. So again, cracks left alone as long as possible are the best looking cravks there are.
Attached is an example of a crack left alone and a crack that has had some “treatment” done. You can see the decision to leave a crack alone is likely the best decision.
When do I ask for a panel of concrete to be replaced? Should it be under warranty?
Since all concrete cracks, its very rare to find a contractor that is uneducated enough to warrant ut completely. However, if a crack develops and widens to over 1/4” within the first calendar year of being placed, this is generally our rule of thumb to warrant a crack treatment or even replace a section of concrete. Mind you, concrete section replacement can also be rather ugly. Colors and textures can vary from new to existing sections.
Cracks are all very common, and the ugliest ones are usually the ones that have been treated. You’ll see cracks in bridge decks, airport runways, roads, and more. They are a fact of life.
Pictured: An untreated crack
A crack that has been “Treated” or “Repaired” 🤮
