Causes of Cracks
There are a variety of factors that can lead to cracks in concrete. Perhaps one the most common causes of cracks in concrete is having too much water in the concrete mix. Although water is added to concrete mix to make it easier to pour, adding too much water can lead to cracking because shrinkage occurs whenever the concrete dries.
Random cracks are those cracks that spread slowly in more than one direction, randomly. They can sometimes be caused by normal shrinkage or by the settlement upon which the concrete was poured. Random cracks can become worse over time, especially if moisture gets between the cracks and freezes, causing the crack to deepen and lengthen. The concrete around the crack may also begin to flake. This type of crack can also appear if stress lines were not properly cut in the newly laid concrete.
Settlement cracks are caused solely by the settlement underneath the concrete. If the settlement under the concrete was not compacted or prepared properly before the concrete was poured, then cracks caused by settlement may appear. Settlements cracks can also begin as random cracks that were caused by unlevel subgrade soil or from the concrete settling unevenly after it was poured. To keep settlement cracks from spreading, it is sometimes necessary to excavate the area and prepare it with sand.
Heaving cracks are those cracks that are caused by hard freezes. Frost heaves can be caused when concrete is poured on soil that retained water instead of draining the water away. Heaving cracks can be also be caused by alternating freezing and thawing temperatures during the winter months.
When cracks develop, it is important for them to be evaluated to determine whether or not they will pose structural problems. Some cracks can simply be eyesores, whereas others can lead to serious problems if they aren’t addressed and fixed as soon as possible.