Despite being one of the toughest materials on the planet, concrete is still susceptible to cracking. These cracks may ruin the aesthetic look of your concrete, and larger cracks may even cause a supported structure to become unstable. Luckily, most of these cracks are easy to fix — check out this article to find out how.

In this article, discover why concrete cracks, the different types of cracks and how you can fix them.

 

Why does concrete crack?

Concrete cracks when its tensile strength is exceeded by the net tensile stresses induced within its matrix. Put simply, concrete cracks when it experiences more tension than it can withstand.

There are a number of circumstances in which this might occur. 

 

Why does concrete crack during pouring/curing?

  • There is excess water in the mix

Sometimes water is added to the concrete mix to make it easier to pour. The problem is that concrete hardens and dries as it shrinks, and it shrinks because the water in the mixture is evaporating. If too much evaporation occurs due to too much water in the mixture, the concrete will shrink and harden too much, creating forces within the concrete that literally pull the slab apart. The result is cracked, weakened concrete.

  • The concrete dries too quickly

The chemical reaction needed for successful curing requires water. If the concrete dries too quickly and there’s not enough moisture retained in the concrete, it may start to crack.

 

Why does concrete crack after curing?

  • It has been crushed by heavy weights

Concrete may crack if its tensile strength is exceeded by a heavy weight. This most commonly occurs when heavy goods vehicles are parked on top of driveways.

  • Heat has caused it to expand

Exposure to heat will cause the concrete to expand. In some circumstances, concrete will be forced to expand against another inflexible material, such as a brick wall. 

  • Water has permeated the concrete and frozen

Water expands when it freezes. If water gets into hairline cracks in the concrete and freezes, it will expand, forcing the concrete apart.

 

Types of cracks

Some cracks are more concerning than others. The different types of cracks in concrete include:

  • Hairline cracks
  • Shrinkage cracks
  • Settlement cracks
  • Structural cracks

 

How to fix concrete cracks

  • Undercut the sides of the crack to create an inverted ‘V’ shape.
  • Use a chisel and hammer to widen the base of the crack and dislodge any loose material.
  • Use a wire brush to remove all debris from the crack.
  • Use a wet/dry vacuum or a brush to remove water and remaining debris from the crack.
  • Mix the concrete patching compound and use a trowel to apply it to the crack, making sure it is even with the surrounding surface.
  • If needed, brush the surface of the patching compound with a paintbrush to texture the surface.
  • Let the compound cure.

 


At EasyMix Concrete, we pride ourselves on delivering exceptional concrete mixes in quantities perfect for your project. Simply use our concrete calculator to determine the volume of concrete you need, and we’ll make it available for collection or delivery. Where possible, we’ll even deliver your concrete the very same day that you place your order, ensuring you can start on your project immediately.

Need concrete fast? Contact our team today.