shotcrete

or gunite

Concrete applied by spraying.

Shotcrete is a mixture of portland cement, aggregate, and water conveyed by compressed air to a spray gun. For structural uses, shotcrete is usually sprayed over a framework of reinforcing bars and steel mesh. Because it can take any shape, is easily coloured, and can be sculpted after application, it is used for a variety of specialized structures, including artificial rock walls, zoo enclosures, canopies, shell structures, pools, and dams. It is sometimes used to bind the walls of tunnels.

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▪ building material

also called  (trademark) Gunite,  

      concrete applied by spraying. Shotcrete is a mixture of aggregate and portland cement, conveyed by compressed air to the nozzle of a spray gun, where water is added. The wet mixture is then sprayed in place and may be carved or troweled almost immediately. For structural uses, shotcrete is usually applied over a framework of reinforcing bars and steel mesh. Because it can take any shape, is easily coloured, and can be sculptured after application, shotcrete is used for a variety of fancy concrete structures, including artificial rock walls, zoo enclosures, canopy roofs, refractory linings, pools, and dams. It is sometimes used in tunneling to bind the walls of the tunnel to prevent leaks and fragmentation.

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