When it comes to concrete, cracking is inevitable. But how much cracking is normal? It depends on the type of crack and the circumstances in which it occurs. If the crack is small and not “active”, meaning one side of the crack is not higher than the other, then it is likely normal. However, if the crack is larger or larger (an “active crack”), or if one side of the crack is higher than the other, you may need a structural engineer to review the work.
To prevent cracking, it's important for concrete contractors to follow well-established guidelines regarding concrete placement. This includes using control joints to weaken concrete in certain areas so that it cracks in a straight line in these spaces. Cold joints, where one section of concrete has hardened before another section is poured next to it, can also cause cracking. Additionally, if sublayers are not well compacted before pouring concrete, the heavy weight of the concrete can cause these areas to sag and then cracks can occur.
It's also important to understand how your contractor will cure concrete. Curing concrete involves keeping it moist and warm for a certain period of time so that it can reach its full strength. If too much water is added to the concrete on the job site, this can also lead to cracking. If you're still unsure about how much cracking is normal for your project, you can always contact a customer service representative or search the ACI Resource Center for more information.
You can also read up on methods for curing concrete and other topics related to decorative concrete on Concrete Decor.