filling caused local hardening in the cartridge whereas for example this local hardening was eliminated by vibrating the tubular casing during filling at 250 cycles per minute for 35 seconds while replacing the metal clip at the bottom of the casing with a heat seal to provide a softer bottom of the cartridge a preferred mixture for the cartridge of this invention in one series of tests was determined to contain 2 0 percent by weight silicone and 1 5 percent potassium sulfate accelerator mixed at 0 29 water microcapsule to cement weight ratio based upon the shortest hardening time when inserting the anchor element and the best workability of any mix tested these cartridges produced using the apparatus of fig1 were readily inserted in the hole of the support structure using one hand the anchor element was inserted in the hole in a screwing motion and after hardening of the grout produced an anchor element which had excellent adhesion to the walls of the hole of the support structure as is indicated by a pull test the reinforcing member of this invention preferably increases the stiffness index of the cartridge of this invention by a factor or 2 or more and more preferably by a factor between 6 and 10 the stiffness index referred to is that given by the test exemplified below two cartridges prepared one with a reinforcing strip and one without as indicated in the example provided hereinabove but having the following specifications ______________________________________diameter 0 935 inchlength 45 inchesweight 520 gms water to cement w c ratio 0 29alpha type gypsum cement 355 gms water microcapsules 165 gms 2400 micron average diameter water microcapsule payload av 621 2 casing thickness polyethylene film containing 0 002 incheva additive to provide elasticity reinforcement.