Concrete is a mixture of cement and several other materials including ash, rock aggregate and slag. Although this mixture when freshly poured can quickly dry into strong concrete, it will be made even stronger when it is cured. Curing is especially important for structures such as concrete steps, which undergo a great deal of wear and continual stress.
The curing process is centered on hydration. This process saturates the concrete with water, allowing the conglomeration of materials to bond more closely. Hydration occurs rapidly at the outset of the curing process, then more slowly for up to 28 days when the concrete gains the maximum hardness and strength known as "28-day hardness." This process is begun by spraying down the concrete occasionally for up to 48 hours after screening. Alternatively, you can lay a damp burlap cloth over the staircase, making contact with all parts of the concrete. Over time, the water will leach from the burlap into the concrete. After 48 hours, the concrete will stop drinking large amounts of moisture and instead draw smaller amounts from condensation as well as the ground it is laid on.
Protecting the concrete while it cures is just as important as moisture is for the curing process. There are several things you'll need to do to protect the concrete, at several stages of the manufacturing and curing process. First, before pouring the concrete, make sure the ambient temperature is not likely to fall below freezing. Freezing temperatures can expand the water in the concrete before it has had a chance to react with the cement. This can undermine the foundation of the concrete and cause cracks and even crumbling of the steps before curing can take place. During the curing process, keep the concrete covered from wind and rain; most importantly, protect the concrete from drought. Excessive drying can cause the concrete to lose its cohesiveness and strength.
Evaporation is a problem even for concrete that has been well cured. Because of this, a masonry sealer or concrete sealer is often used to protect the moisture locked inside concrete steps. This sealer can be sprayed or brushed on and prevents concrete from evaporating or weakening in the heat of the sunlight.
Many people choose to paint their concrete steps. Although paints protect the concrete from the sun and lend a colorful beauty to the steps, paints are less capable of sealing in moisture. Additionally, paint can easily be worn away by foot traffic.