A number of different kinds of chemicals and materials can be added to concrete to improve its performance. Contractors often add fiber made of glass or another material to improve its strength.

There are also two general types of concrete "admixture." Mineral admixtures such as fly ash, silica fume and slags enhance the workability of fresh concrete, improve resistance to such problems as cracking, alkali-aggregate expansion, and sulfate attack, and allow producers to cut down on cement content. Chemical admixtures are added in very small amounts to change the properties of the mix. There are five specific kinds. They affect air entrainment, water reduction, plasticization, and acceleration or retardation of setting time.