The best type of concrete for a patio is concrete that contains air entraining admixtures. This type of concrete is full of tiny air bubbles that keep it from spalling during freezes. The bubbles also protect the concrete if it's going to be subject to deicing salt.
Admixures that slow down the setting time of the concrete are added if the patio is built during hot weather. They are also used if the patio has decorative elements, such as exposed aggregates. Conversely, the builder can also add accelerators that makes the concrete set faster. Fly ash, which is the residue from coal burning, is added to keep the concrete cooler.