Concrete acts in a similar manner. After being properly cured concrete will also shrink as it dries. An average concrete slab will shrink 3/4 of an inch for every 100 feet of length. The underside, bound to the sub-grade that prevents it from contracting over its entire length builds internal stresses resulting in shrinkage cracks generally spaced about 20 feet apart.

Unfortunately, excess water is sometimes added to the concrete load at the job site. Making the concrete easier to handle by adding water is a short-term solution that will leave long lasting results - more cracks. The wetter the mix laid down, the more it will shrink and crack.  Unplanned cracks are usually in the wrong place and never straight.

We can design cracks that are pleasing to look at. They are called joints. By grooving the slab at predetermined intervals before it sets, or saw cutting it shortly after setting, we can force the cracks to appear where we want them. As an added bonus the crack is hidden beneath a surface feature that can very aesthetically attractive.

Curing is the final step in the process of producing a quality concrete slab. Curing entails keeping the surface of the concrete wet and safe from freezing. Curing during warm weather is accomplished using sprinklers, wet burlap, soaker hoses or a combination thereof. If there is a danger of freezing, thermal blankets, usually available at tool rental stores, should be put over the wet burlap.

Concrete that has not been cured but allowed to dry out the next day will tend to have more unsightly cracks. It simply lacks the strength needed to hold itself together. Curing is essential for three days, and recommended for seven days, to prevent unwanted shrinkage cracking.