Abstract: The surface of hydraulic concrete must be protected and repaired to improve its durability. To this end, a new type of CW series concrete surface protection and patching materials, namely nano-silicon dioxide/polyurea composite materials were synthesized by researchers in Yangtze River Scientific Research Institute. The materials were produced through ultrasonic dispersion by adding organosilane coupling agent, reactive diluent and nano-silicon dioxide to the synthcticfat of polymerization of polyaspartic esters and isocyanates. Meanwhile, the effects of ultrasonic dispersion time, the amount of nano-silicon dioxide, and the type and amount of isocyanate on the properties of the composites were explored. It was found that the newly developed materials were environmentally friendly, highly durable and cohesive and could be easily operated under dry and wet conditions, which could effectively improve the properties against ultraviolet aging, abrasion, permeability, carbonization, frost, and chemical corrosion of concrete. In this sense, they can be widely used in danger-eliminating and reinforcing for old hazardous reservoirs, surface protection and crack repairing of new hydraulic constructions, as well as other anti-seepage and anti-aging projects in hydraulic engineering. Up until now, the materials have been applied in the danger-eliminating and reinforcing of Three Gorges Dam, Danjiangkou Dam, the Middle Route Project of the South-to-North Water Diversion Project, Yichang Tangduhe reservoir and Shangjiahe reservoir.

Key words:  polyaspartic esters  ,   polyurea  ,  nano composites  ,  hydraulic concrete ,  , durability