A rock-dowel has a dowel shank and a threaded end at the head or proximal end of the dowel. Three groups of projecting mixing vanes are spaced along the shank. In use when inserted into a pre-drilled hole containing a two-part encapsulating resin and spun, the rock-dowel can thoroughly mix the two part resin encapsulating resin and force the resin casings into the back of the pre-drilled hole. Also disclosed is a nut made from a plastics material defining a first, typically relatively wider, barrel portion and a second, typically relatively narrower, nut portion, the second portion defining a nut section for engagement with a socket, wherein an area of weakness is provided between the first and second portions such that the second portion breaks from the first portion when a particular torque value is applied to the nut.