Advantages
Today, both wet- and dry-mix systems of shotcrete emplacement have applications in rock support. Introduced in 1955, wet mix has the advantages of being able to achieve better material consistency through off-site mixing, producing less dust, and achieving greater volumes in a given time. Dry mix (in which water and admixtures are added to dry materials at the nozzle) is claimed to offer easier control over the mix, and has definite advantages when small areas, requiring small amounts of material, are being sprayed. It does, however, have the disadvantages of producing more dust, and a greater proportion of the material ends up on the floor as rebound.