混凝土外加剂在30年代美国首先开始使用,五十年代得到迅速发展和应用。目前,世界各国的混凝土外加剂已达300多种。我国在五十年代开始生产应用外加剂,目前品种为100多种。外加剂按功能可分为五类:(1)改善混凝土流变性的外加剂。(2)调节硬化时间的外加剂。(3)调节空气含量的引气 Concrete admixtures first began to be used in the United States in the 1930s, and the rapid development and application in the 1950s. At present, there are more than 300 concrete admixtures in various countries in the world. In the 1950s, China began to produce additive applications. At present, there are more than 100 varieties. Admixtures can be divided into five categories according to their functions: (1) Admixtures for improving the rheology of concrete. (2) Admixtures for adjusting the hardening time. (3) Air bleed air conditioning