Abstract: This specification describes a new anchor or rock nut which is used in association with an anchor bolt to rupture packages of two or more component setting mixtures. The nut is characterized by having a plug of thermosetting resinous material formed in situ which plug may be removed by the anchor bolt when screwed into the nut under the application of a pre-determined force which cause the plug to crumble; however until the predetermined force is reached the nut will cause the bolt to rotate.