Concrete cracks caused by premature drying Residential homeowners who place large recreational vehicles or dumpsters on their driveways are more likely to see this type of cracking. Instead, what is more likely to occur is excess overload on the ground below the slab.Īfter a heavy rain or snowmelt when the ground below is soft and wet, excessive weight on the slab can press the concrete down and result in cracks. When it comes to residential concrete slabs, overload of the actual slab isn’t all that common. When you hear a concrete mix has a strength of 2000, 3000, 4000, or 5000+ PSI, it is referring to the pounds per square inch it would take to crush that concrete slab. Placing excessive amounts of weight on top of a concrete slab can cause cracking. Concrete cracks caused by overloading the slabĪlthough concrete is a very strong building material, it does have its limits. and don’t compact the soil when they refill it–these are examples of instances where settling cracks are likely to happen. Think about when a large tree is removed from nearby and the roots begin to decompose or when a utility company digs a trench for their lines, pipes, etc. Settling cracks typically occur in situations where a void is created in the ground below the concrete surface.
On the other hand, ground settling below a concrete slab can also cause cracking. If a tree is located too close to a slab, the growing roots can lift and crack the concrete surface. Large tree roots can have the same effect on a slab.
#Live edge slab crack repair free
If the slab is not free to move with the ground, the slab will crack. This ground movement brought on by the freezing and thawing cycle is a huge factor contributing to concrete cracking. When the ground freezes, it can sometimes lift many inches before thawing and settling back down. Typically made of a compressible material like asphalt, rubber, or lumber, expansion joints must act as shock absorbers to relieve the stress that expansion puts on concrete and prevent cracking. When neither has the ability to flex, the expanding force can be enough to cause concrete to crack.Įxpansion joints are used as a point of separation (or isolation), between other static surfaces. When concrete expands, it pushes against anything in its way (a brick wall or adjacent slab for example). Just like a balloon, heat causes concrete to expand. The joints will open up as the concrete slab gets smaller. Hot weather is another big reason for plastic shrinkage cracks.Ĭontrol joints can be incorporated into the slab to prevent shrinkage cracking. When the mix contains too much water, the slab will shrink more than if the correct amount of water was used. While water is an essential ingredient in every concrete mix, there is such a thing as too much water. While nearly invisible, it is important to remember that plastic shrinkage cracks don’t just exist on the surface, they extend throughout the entire thickness of the slab.Īn excessively wet mix is a contributing factor to shrinkage in concrete. Plastic shrinkage cracks are typically very narrow in width and barely visible. Since concrete cannot shrink around a corner, stress will cause the concrete to crack from the point of that corner. While plastic shrinkage cracks can happen anywhere in a slab or wall, they almost always happen at reentrant corners (corners that point into the slab) or with circular objects in the middle of a slab (pipes, plumbing fixtures, drains, and manholes). This type of cracking happens frequently and is referred to as “plastic shrinkage cracking”.
These empty spaces make the concrete weaker and more prone to cracking. When that water eventually leaves the slab, it leaves behind large voids between the solid particles.
#Live edge slab crack repair full
When concrete is still in its plastic state (before hardening), it is full of water. We explain 6 of the most common types of concrete cracks below. Consequently, every owner should be advised by both the designer and contractor that it is normal to expect some amount of cracking and curling on every project, and that such occurrences do not necessarily reflect adversely on either the adequacy of the floor’s design or the quality of its construction ” “Even with the best floor designs and proper construction, it is unrealistic to expect crack-free and curl-free floors. Actually, concrete cracks are very common, some are even inevitable.Īmerican Concrete Institute touches on the issue of cracking concrete in their American Concrete Institute manual, ACI 302. When you see a crack in your concrete slab or wall, your first assumption is typically that something has been done wrong–but that’s not always the case. Six Common Types of Cracks in your Concrete
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