What is the difference between an admixture and an addition?
In concrete parlance the word admixture is used to designate a material added to the concrete mixture, either before or during mixing, to modify its properties in some way. The word addition applies to materials that are interground or blended with portland cement either to aid in manufacture or to modify the way the product behaves. Some materials, notably air-entraining agents, may be used either as additions or admixtures to accomplish a single purpose. The word additive is sometimes used in the same way as addition but it should not be used to mean admixture.