A plug member (10) for retaining grout in a cable bolt hole or a rockbolt hole or inside a rockbolt in underground excavations, comprising a cylindrical cap portion (20) with a means to wedge (26) the cap portion in the hole. The means to wedging means (26) may comprise a plurality of inclined flaps, a continuous resilient skirt, or a tapered bung. The cap portion (20) is provided with at least one port (50) to receive a grout delivery hose. The or each port (50) is comprised of a plurality of flexible flaps (56) moveable between an open position and a closed position. In the closed position the flaps (56) inter-engage to substantially close the port (50) and prevent grout leakage from the hole.