ABSTRACT
Chemical admixtures are frequently used in concrete for the purpose of altering one or more of its properties in the fresh or hardened state. In addition to mainstream applications of water reduction, retardation, acceleration and air entrainment, chemical admixtures are used for a variety of special purposes. Included in this category are both conventional admixtures, used in unusual ways, and special admixtures designed for specific applications. By their mode of action these chemicals, when used singly or in combination with other admixtures, broaden the scope of applications of concrete. New and specialized types of concrete such as cohesive underwater concrete and roller-compacted concrete requiring varying placement methods, concreting in the depth of winter without conventional heating and protection methods, corrosion inhibition in the presence of chlorides, reducing alkali-aggregate reaction, shrinkage control, the recycling of concrete waste, and the production of highly durable high-performance concrete are now made possible through the use of admixtures.
