Shrinkage cracks are very common, especially in cast-in-place concrete walls. They are a type of thin, thin crack that does not go through the entire wall, but is very shallow or only on the surface. 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.
Fine cracks in concrete are very common, but they are not well understood. When most people see a crack in the concrete, especially when it's new, they assume there's a problem. But fine cracks are usually not a cause for concern and are mostly cosmetic. Although that doesn't mean they should be ignored.
Fine cracks in a basement wall are normal occurrences. Foundation walls crack over time as they begin to settle and dry out. For some walls, it takes about a month before these cracks begin to form. Fine cracks can develop in concrete foundations as the concrete cures.
Fine cracks do not cause problems with the stability of the base, but they do cause leakage problems. If cracks appear soon after pouring the concrete base, it is possible that the concrete was mixed poorly or poured too quickly. In poured concrete foundations, fine cracks often appear in the center of walls because the corners of the walls have greater stability. Therefore, when analyzing the causes of cracking within a concrete masonry wall, it is imperative that one fully understand all of the mechanisms associated with cracking of concrete masonry.
While shrinkage in concrete masonry varies, there are the shrinkage coefficients published within of ACI 530-11 (American Concrete Institute). A more massive vertical crack can occur when construction contractors improperly prepare concrete foundations and when the wall had poor steel reinforcement when workers poured concrete for the wall. In the case of concrete masonry assemblies, a typical concrete block has a compressive strength of approximately 2000 psi, as do most common mortars. A reputable local concrete driveway professional will know the best way to keep a concrete slab in good condition for optimal curing.
After the concrete has fully cured, you can also consider using a concrete sealing compound to improve appearance and reduce cracking. Fine cracking within concrete block walls as a result of concrete masonry shrinkage is an anticipated fact. If your concrete is a little older, a concrete repair professional can help you fix the cracks. ACI 116R-90, Cement and Concrete Terminology, defines fine cracks as cracks in an exposed concrete surface that have widths so small that they can barely be perceived.
If cracks appear right after pouring a concrete base, the concrete may have dried too quickly, mixed poorly, or overworked. 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 addition to these traditional curing methods, concrete additives and curing compounds can help concrete cure faster and resist cold.
