Fine cracks in a concrete slab are rarely a cause for concern, and can be controlled but not eliminated. In about a month, these cracks should disappear, as it takes a full month for new concrete to fully settle. This phenomenon is known as plastic shrinkage, and is caused by the rapid depletion of moisture from fresh concrete into its plastic state. The main cause of fine cracks in concrete is shrinkage.
As concrete dries, it becomes hard and strong, but if it loses moisture too quickly, small cracks can form. To avoid this, reduce the speed of the drying process by keeping the concrete surface moist. This can be done by covering the concrete with an insulating plastic sheet or even straw to trap moisture and help the concrete cure at an even rate. Cracks that crack are very fine surface cracks that resemble cobwebs or broken glass.
These are not a structural concern, but can be unsightly. Control joints are designed to weaken concrete in certain areas, so that concrete cracks in a straight line in these spaces. If your concrete is a little older, a concrete repair professional can help you fix the cracks. Crust cracking generally occurs during the concrete stamping process, which is a way of adding texture or pattern to concrete surfaces. If cracks appear right after pouring a concrete base, the concrete may have dried too quickly, mixed poorly, or overworked. A reputable local concrete driveway professional will know the best way to keep a concrete slab in good condition for optimal curing.
This means that, as the concrete contracts, steel springs help the concrete contract in the ground it sits on, preventing cracks from forming or, at least, spreading apart.