Inflatable mine support

An inflatable bag for use in a mine support has an inlet for the admission of a pumpable load bearing material such as a cementitious grout and an outlet for the air. The outlet is provided with a valve comprising a porous element the pores of which are capable of being blocked by the grout or similar load bearing material whereby the valve is closed by the grout and the pressure in the bag increased. The porous element can comprise a sponge. The bag is preferably made of a heat sealable material such as a synthetic plastics material e.g. polyethylene. The bag is used with a tube in which it is placed with the inlet in alignment with an aperture in the wall of the tube and grout pumped into the bag to inflate the bag against the floor and roof of the mine.