The present invention relates to a rock bolt comprising first and second ends, a shaft extending between the ends, and an anchoring device extending along a first part of the shaft adjacent the first end. The anchoring device comprises a mandrel, and at least one expansion element overlaying the mandrel. The expansion element is displaced radially outwardly on a predetermined relative movement between the mandrel and the expansion element. The expansion element is joined to a connector to form an anchor assembly. The anchor assembly is keyed to the mandrel. The anchor assembly comprises relative rotation actuator means active during rotation of the anchoring device. The invention further relates to an anchoring device per se.