Why Does Concrete Crack?

Crack on concrete floor

Concrete is always going to be a builder’s best friend. It’s known to be universally strong, durable, and versatile. Its affordability and thermal mass make it an eco-friendly material too, so it’s not surprising to know that concrete is among the world’s most-used materials for building. But concrete has the probability to crack, and in most cases, there’s just nothing that you could do about it. You might ask yourself why, and that’s why we have the answers to that question including pointers as to how you can diminish those causes from happening.

 Concrete Destiny

Over the course of time, weather and wear eventually occur and your concrete will develop a hairline crack at the very least or even multiple cracks. There are many reasons why concrete cracks—some can even begin to appear only hours after the drying process.

 There is an old quote saying that there are two kinds of concrete: concrete that will crack and concrete that is cracked.

 Why Does Concrete Crack?

How is that for something that looks super strong and stable, gorgeous indoors and outdoors, will eventually crack as time passes? Factors like soil upheaval, expansion, and the freeze-thaw cycle can all guarantee a sure amount of damage to your perfect-looking concrete surface. Sadly, it won’t stay as gorgeous as you want it to be forever.

But more immediate factors are commonly responsible for the early hairline cracks that can damage your concrete slabs as soon as they’re poured.

Multiple cracks on concrete floor

Shrinkage Cracks

Hairline cracks on the concrete are common and cannot be entirely avoided. The most common type of this crack is what we call the shrinkage crack, which happens when water evaporates from the concrete mix as it undergoes hardening. Moist concrete fills a defined space; but as it dries, water evaporates and the reduced volume pulls the concrete apart.

Concrete Floors and Countertops

Your indoor concrete surface has the same odds of cracking just as exterior concrete slabs do. This is often the disadvantage of having an exposed interior concrete surface. The good news for you is that interior floors are typically large and structurally designed, with more reinforcements than that of an outdoor patio.

Control Joints

These are separations on the outer layer of the concrete surface. It provides a weakened location across the visible plane where hairline shrinkage cracks occur. However, these cracks are not visible. Concrete installations that are done during hot weather can often develop more shrinkage cracks than those that are poured under more moderate weather conditions. The quick drying caused by the heat would require more water to be used with the concrete during the pour. The poured concrete fills a defined space and as evaporation and hardening occur, the water would disappear. If there’s too much water in a soupy concrete mix, the remaining matter is forced to fill the excess volume, pulling the concrete apart. In short, too much water can cause shrinkage that results in more hairline cracks. Proper control joints and using synthetic fibers and enough rebar can help control cracking.

Expansion Cracks

Hot weather can cause slab expansion, even in old concrete slabs. Without the proper expansion joint where the forces of two static objects meet (similar to bricks and concrete slabs), the force of the expansion can cause a substantial amount of cracking over time.

Heaving and Subsidence

Tree roots, freeze-thaw cycles, and other forces of soil movement are the natural causes of concrete cracks. Making sure that a slab is not installed too near mature trees, and not planting new trees closer than 20 feet from concrete, can help reduce the effect of thrusting roots.

Special thanks to Houzz for the info about concrete cracks! To learn more about concrete crack repair solutions, check out our site!

Scroll to Top