Carl Akely patented his process and the equipment it require.  Akely’s process involved spraying from a dry mixed hopper of concrete using a nozzle which introduced water to the mix at the point of departure from the nozzle.

This technique is still used, and is known as “shotcrete – dry mix”, to distinguish it from a later process which sprays ready-mixed wet concrete known as “shotcrete – wet mix”. Each has its advantages, but both require skilled operators.