Rather than unsightly, cracks are susceptible to water ingress that can freeze and thaw, expand and contract repeatedly, making the crack worse. The crack can also allow water to destabilize the soil under the concrete, compounding the problem. Yes, in about a month, fine cracks should disappear. While shrinkage cracks can appear on the surface within hours of pouring concrete, it takes a full month for new concrete to fully settle.
CSC), as we know it today, was formed in 1958 through the merger of three premixed companies. When the concrete is still in the plastic state (before hardening), it is filled with water. When the water finally comes out of the slab, it leaves large voids between the solid particles. These voids make concrete weaker and more prone to cracking.
This type of cracking occurs frequently and is known as “plastic shrinkage cracking”. I am often asked about cracks in concrete foundations. Many homeowners get nervous when they see cracks in the concrete and wonder if they are bad or dangerous. While it's a natural reaction to worry when you see something cracked, the reality is that 95% of cracks in concrete are harmless and there's nothing to worry about.
As a general rule, any concrete slab longer than nine feet will crack. I'm sorry for one of those who say that the floor in their basement never had cracks. You probably haven't noticed them. Tight cracks are common in concrete slabs.
In general, if the crack is stable and does not leak water, it does not indicate a structural problem. In most cases, these are shrinkage cracks that formed when the concrete cured. Crust cracking generally occurs during the concrete stamping process, which is a way of adding texture or pattern to concrete surfaces. For a narrow crack like this, you can use a self-leveling concrete crack filler to seal the crack before painting or finishing the surface.
In addition to these traditional curing methods, concrete additives and curing compounds can help concrete cure faster and withstand the cold. If your concrete is a little older, a concrete repair professional can help you fix the cracks. Concrete cracks may seem scary at first, but they are common in almost every home that has a concrete floor. When you hear that a concrete mix has a strength of 2000, 3000, 4000, or more than 5000 PSI, it refers to the pounds per square inch that would be needed to crush that concrete slab.
Proper site preparation, quality mixing and good concrete finishing practices can go a long way in minimizing the occurrence of cracks and producing a more aesthetically pleasing concrete project. Read here about methods to cure concrete and understand how your contractor will cure concrete. A reputable local concrete driveway professional will know the best way to keep a concrete slab in good condition for optimal curing. In addition, concrete poured in mid-summer will have more cracks than concrete poured when it is colder.
Since concrete cannot shrink around a corner, stress will cause the concrete to crack from the point of that corner. Instead, cover the concrete with an insulating plastic sheet or even straw to trap moisture and help the concrete cure at an even rate. In general, cracks wider than a credit card and going through the depth of concrete are structural in nature and could be a sign of more serious problems (see Evaluating Concrete Crack Repair). However, a large majority of concrete used in residential work has too much water added to the concrete on the job site.