Abstract: A ground hardening material injector comprises a monitor connected to the top of an injection pipe, which monitor includes an upper injection means disposed in the side wall of the monitor and a lower injection means disposed in the opposite side wall of the monitor. The upper injection means further includes an inner injection nozzle for injecting compressed liquid and an outer injection nozzle for injecting compressed gas, and the lower injection means further includes an inner injection nozzle for injecting compressed ground hardening material and an outer injection nozzle for injecting compressed gas.

Abstract: Reinforcing or fixing elements such as anchor bolts are anchored in a borehole drilled in a substrate such as an underground mine roof with an anchoring cartridge in which a particulate liquid-settable solid component, for example a hydraulic cement, is contained in a liquid-impermeable casing, the solid occupying a volume which is less than the normal free volume of the casing and the cartridge being at least partially evacuated so as to cause the casing to be in contact with the solid component over substantially its whole length within the casing. This ensures that when the cartridge is immersed in an activating liquid, for example water, and the casing perforated, the activating liquid is drawn rapidly into the evacuated space adjacent the solid component over its whole length thereby helping to ensure the formation of a self-setting grouting composition of uniform strength when the cartridge is used.