混凝土外加剂的使用已有五十多年的历史.这已被公认是提高混凝土强度及改善混凝土各种性能的有效手段.由于外加剂在混凝土工程中获得日益广泛的应用,许多地方已把它作为混凝上中除水泥、砂、石、水以外的第五种材料.近年来,随着人们对节约能源的重视,进一步促进了外加剂的发展.一些国家(如日本、挪威等)几乎在全部混凝土中采用了外加 The use of concrete admixtures has been in use for more than 50 years. This has been recognized as an effective means to increase the strength of concrete and improve the properties of concrete. As admixtures are increasingly used in concrete engineering, many places have As the fifth material in addition to cement, sand, stone, and water, in recent years, with the emphasis on energy conservation, people have further promoted the development of admixtures. Some countries (such as Japan, Norway, etc.) are almost Used in all concrete