Q. Show the Direction of gunning in shotcreting?

At the time of the construction of shotcrete, it is intended at gunning the full thickness in one single operation and this helps to decrease the occurrence of possible delamination and formation of planes of weakness. Furthermore nozzles must be held about 0.6m to 1.8m from the surface and normal to the receiving surface. Reason of gunning perpendicular to receiving surface is to avoid the possible rebound and rolling resulting from gunning at an angle deviated from the perpendicular. Rolled shotcrete creates a non-uniform surface that serves to trap overspray and shotcrete resulting from the rebounding action. This is undesirable due to the wastage of materials and generation of rough and uneven surface.