How have shotcreting techniques and shotcrete changed in the last 20 years?
Hulls: Shotcrete was predominantly dry mix 20 years ago, the trend now is for the majority of sites to use wet mix, especially since the early 90s. Application 20 years ago and more was for shotcrete to be applied by hand, hence the common term ‘nozzleman’. Machine based application evolved during the late 80s and early 90s, with the ‘nozzleman’ now operating a set of remote levers to apply the shotcrete via a robotic arm. The first fully robotic machine (no operator required) was tested in 1999. Initial admixtures were very caustic and not really user friendly, with alkali free, non-caustic admixtures first introduced in 1994. Shotcrete mix quality is improving rapidly with the introduction of electronically controlled batch plants at many sites.
