A mixing head attachment is provided for use in mixing grouts and/or resins (hereinafter for brevity collectively referred to as resin) used in mine roof support systems in the securement of an anchor bolt in a bore hole. A threaded fastener is provided to tension the anchor bolt, and a resin composition is used to secure at least part of the anchor rod in the bore hole. The mixing head attachment is provided with a rigid or semi-rigid body which extends axially along a body axis, and has sufficient structural integrity to effect mixing of unset resin as the mixing head is rotated about its axis. The mixing head attachment includes one or more mixing blades or projections which define a mixing surface or face. A recess is formed in a proximal-most end of the body, sized and shaped for mated engagement with a distal end of the anchor bolt, allowing mixing head attachment to be in generally co-axial arrangement to the anchor bolt with a sufficient minimum contact force selected so that while the resin remains unset, the rotation or spinning of the anchor rod in the bore hole effects rotation of the mixing attachment about its axis therewith.