A concrete mix must provide adequate durability. However concrete mixes are not normally tested for durability directly; instead concrete specifications frequently contain mix requirements, which are designed to provide durability by ensuring that the set concrete attains a minimum strength.
Sometimes a minimum concrete strength is specified. Alternatively specifications may lay down a maximum Free water/Cement ratio or a minimum cement content.
It has been found that the resistance of concrete to frost damage is greatly improved by air entrainment.
Sulphate Resisting Portland Cement may be used for concrete that will be exposed to sulphates.