Abstract: The water immune polyurea concrete surface protection material independently developed by Yangtze River Scientific Research Institute is prepared from modified polyaspartic acid ester and isocyanate by adjusting and controlling the molecular structure and aggregate structure. It is not to be deteriorated by water in the environment; that is to say, it is immune to water. Such water immunity reduces the impact of service environment on material performance and construction, and addresses the critical problems in engineering application of polyurea. It has proved excellent application effect in large and medium-sized key projects such as Danjiangkou Reservoir, high-fill canal of middle route of South-to-North Water Diversion Project, Yellow River crossing tunnel, Xiluodu Hydropower Station, and Shangjiahe Reservoir over the past decade. The material is of great development and application value and prospect in the field of water conservancy and hydropower, and is expected to be applied in municipal administration, transportation, marine engineering and other areas of infrastructure and national life.

Key words: Polyurea, water immunity, concrete, surface protection material, slow reaction, hydraulic engineering