Shotcrete

Shotcrete is a method of applying concrete, made with smaller sized aggregates, projected at high velocity through a hose & nozzle system, primarily onto a vertical surface. The impact created by the application consolidates the concrete. Although the hardened properties of shotcrete are similar to those of conventional cast-in-place concrete, the nature of the placement process results in an excellent bond and requires less formwork.

A primary application for Shotcrete is the construction of swimming pools which have vertical and sometimes curved walls and floors.  Because Shotcrete has a lower water-to-cement ratio than typical cast-in-place concrete and is applied at velocity and pressure, Shotcrete will stack up vertically without falling.  

Shotcrete is also used in the construction of canal linings, ponds, small lakes, water features, skate parks, retaining walls, tanks and silos.  For additional information, see  https://shotcrete.org/