Patent ID: 7963726

Claim:
A plastic rock dowel for use in reinforcing strata or the like having a generally cylindrical shank, the shank having a diameter and defining a longitudinal axis, a head at one end and a tip portion at an opposite end, wherein a threaded portion is provided at the head for receiving a nut, and wherein a first group of spaced apart mixing vanes which project at least substantially 2.5 mm from the shank are defined at or adjacent to the tip portion of the shank the vanes increasing an effective spin diameter of the rock dowel by from 15 to 50% compared with the diameter of the shank, and wherein the first group of vanes comprise first and second opposed sets of vanes separated by longitudinally extending gaps with a first sets of vanes projecting from one side of the shank and a second set projecting from a diametrically opposed side of the shank and wherein the first and second sets of vanes are part-helical, the vanes of the first set having a generally left handed thread such that as the shank is rotated in a clockwise sense about its longitudinal axis the vanes tend to push material towards a head of the dowel and the vanes of the second set having a generally right handed thread such that as the shank is rotated in a clockwise sense about its longitudinal axis the vanes tend to push material towards a tip of the dowel.