Dry mix sprayed concrete dates back to around 1911, when it was first developed by the Cement Gun Company of Pennsylvania as a protective waterproofing material for housing.
It was later developed as a smooth finishing coat applied over concrete on high profile buildings like the Los Angeles Public Library. In the 1920s and 1930s the material, now known as gunite, was increasingly used as a water resistant concrete repair material for buildings and major structures like reservoirs, dams and bridges.
An old Cement Gun Company brochure claims that the material saved the city of Nashville, Tennessee $1M in 1922 after contractors used it to rebuild two concrete bridges condemned as unsafe by the city engineer 'due to faulty aggregates'.
The material was even tested by US Shipping Board Concrete Ship Division and as a result was used to protect the surface of concrete-hulled ships against the destructive action of salt water.