This document discusses commonly used admixtures for concrete. It describes the basic uses of these admixtures. It is targeted at those in the concrete industry not involved in determining the specific mixture proportions of concrete or in measuring the properties of concrete. Students, craftsman, inspectors, and contractors may find this a useful introduction to a complex topic. The document is not intended to be a state-of-the-art report, a user guide, or a technical discussion of past and present research findings on the subject. More detailed information is available in ACI Committee Report 212.3R Chemical Admixtures for Concrete and 212.4R Guide fo the Use of High-Range Water-Reducing (Superplasticizers) Admxiture in Concrete.