So why does concrete crack?

If you want a scientific explanation, please see google..

If you want a concrete contractor’s explanation who has obsessed about concrete cracking since he opened his business, read on!

It is important to understand before reading about the types of cracks what expansion cuts are. Concrete expands and contracts with weather and as it cures, and large slabs are guaranteed to crack. The challenge of the contractor is to know where that concrete will crack, and install expansion joints (usually 1/3 of the thickness of the slab deep) in the correct places. Then, as the concrete cracks, it cracks inside of the expansion joints making it a much cleaner look. Now, ON TO THE CRACKS!

  • “Sympathy” Cracks-When a crack begins in a section of the slab, it is usually going to keep cracking until it finds an exit. If the job is jointed correctly, that usually means until the next expansion cut. Most of the time, however, the crack will transfer through the expansion cut into the adjoining slab. I call this sympathy cracking (since the good slab is sympathetic to its neighbor slab and continues the crack).
  • “T” Cracks-These are super common! For some reason, concrete finishers often end expansion cuts into another expansion cut at a “T” instead of continuing the cut all the way to the edge of the slab. That is why in a correctly poured driveway you will see “Y’s that go out to the edges eliminating impossible 90 degree turns that cracks can rarely make.
  • “Settlement” Cracks-This is usually the fault of the contractor. When concrete cracks, and then sinks there is a problem with the substructure, or the concrete is too weak to handle the weight of whatever is on top of the concrete. There ate some other unavoidable factors, however, such as broken pipes underneath the surface, or rotten unknown trash or roots underneath the dirt below the concrete.
  • “Controlled” Cracks-These are the ones you want. Cracks inside of the expansion cuts that are installed. I always get concerned calls from customers when they see 1 day old concrete cracking in the expansion cracks, and they are often confused when they hear me let out a “YES!” in celebration! That means we did our job perfectly, and concrete cracked where it was supposed to.

We have an excellent 2 year warranty that covers major cracking in concrete. We take pride in our work and do our best to prevent major concrete in our work. Feel free to contact us regarding any question you have!


Minor Crack

Major Crack