Even when you don't see them, the slabs are tied with networks of microcracks that result from common shrinkage. When new concrete hardens, shrinkage always occurs. And because concrete is not an elastic material, cracks are unavoidable and are rarely a cause for concern. 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 are commonly observed in freshly laid concrete and their appearance is due to the phenomenon of plastic shrinkage. As the name implies, these cracks are very small, about 0.003 inches (0.08 mm) wide and can be very shallow. Both major structural cracks and fine cracks are often caused by stress relief.
When the tensile stress created is greater than the total withstand capacity, a crack formation occurs. Fine cracks can develop in concrete foundations as concrete cures. Fine cracks do not cause problems with base stability, but they do cause leakage problems. If cracks appear soon after pouring the concrete base, the concrete may have been 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. The most common cause of fine cracks in concrete is drying too fast. So the best way to prevent them is to slow down the drying process. Rapid moisture loss due to hot weather, dry air, additives, aggregates, chemicals, poor workmanship and more can be addressed in a variety of ways.
Shrinkage cracks in a poured concrete base can be diagonal or vertical and typically have a uniform width. Since most fine cracks do not affect the structural integrity of a countertop, sealing and concealing the crack are the primary objectives of a repair. So, of course, it's frustrating to spot fine cracks, especially if you've just paid for a new driveway, concrete slab, walkway, or garage floor. A settlement crack can also appear as a random crack above areas where the subgrade soil was uneven after pouring the concrete.
Adding more water can help make concrete easier to work with, but once the water dries, it can cause cracks. Since most fine cracks do not affect the structural integrity of the slab, the main purpose of the repair is to seal the crack. If you notice fine cracks in the concrete, don't worry, there are a few things you can do to repair them. Unless control joints have been included in the design of the wall or floor slab, these stresses could cause the wall or floor to crack in a classic pattern of concrete shrinkage as the concrete cures.
ACI 116R-90, Cement and Concrete Terminology, defines fine cracks as cracks in an exposed concrete surface that has widths so small that they can barely be perceived. The causes of these cracks can be due to variations in air temperature, concrete temperature, relative humidity and wind speed on the concrete surface. If cracks appear right after pouring a concrete base, the concrete may have dried too quickly, mixed poorly, or overworked. When cracks can't be prevented, concrete contractors often use control joints to, well, control where the cracks will end up.
A friend of mine has a house on the side of a hill, and his yard has had cracks in the concrete for decades. This technical definition of a thin concrete crack doesn't provide an exact width, but you'll recognize one when you see it because they're so small. .