本文件讨论了混凝土常用的化学外加剂，并描述了这些外加剂的基本用途。它针对的是混凝土行业中那些不参与确定混凝土的特定混合比例或测量混凝土性能的人。学生、工匠、检查员和承包商可能会发现这是一个复杂主题的有价值的介绍。本文件不打算成为最先进的报告、用户指南，或对过去和现在的研究结果进行技术讨论。

This document discusses commonly used chemical admixtures for concrete and describes the basic use 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 the concrete. Students, craftsmen, inspectors, and contractors may find this a valuable introduction to a complex topic. The document is not intended to be a state-of-the-art report, user's guide, or a technical discussion of past and present research findings.