Shotcrete

Shotcrete is concrete (or sometimes mortar) conveyed through a hose and pneumatically projected at high velocity onto a surface, as a construction technique. It is reinforced by conventional steel rods, steel mesh, and/or fibers. Fiber reinforcement (steel or synthetic) is also used for stabilization in applications such as slopes or tunneling

Shotcrete is usually an all-inclusive term for both the wet-mix and dry-mix versions. In pool construction, however, the term "shotcrete" refers to wet-mix and "gunite" to dry-mix. In this context, these terms are not interchangeable (see "Shotcrete vs. gunite" discussion below).

Shotcrete is placed and compacted at the same time, due to the force with which it leaves the nozzle. It can be sprayed onto any type or shape of surface, including vertical or overhead areas.

History

Shotcrete, then known as gunite (/ˈgənīt/), was invented in 1907 by American taxidermist Carl Akeley to repair the crumbling facade of the Field Columbian Museum in Chicago (the old Palace of Fine Arts from the World's Columbian Exposition). He used the method of blowing dry material out of a hose with compressed air, injecting water at the nozzle as it was released. In 1911, he was granted a patent for his inventions, the "cement gun", the equipment used, and "gunite", the material that was produced. There is no evidence that Akeley ever used sprayable concrete in his taxidermy work, as is sometimes suggested. F. Trubee Davison covered this and other Akeley inventions in a special issue of Natural History magazine.