Fastening element assembly

An axially elongated fastening element assembly for insertion into a prepared borehole having a transverse shape generally conforming to the transverse shape of said fastening element assembly, comprising a tie bolt and an expanding wedge each elongated in the axial direction of the fastening element, said tie bolt and expanding wedge each having a first end which is inserted first into the borehole and a trailing second end, each of said tie bolt and expanding wedge having a first axially extending surface forming a part of the exterior circumferential surface of the fastening element and a second axially extending surface located interiorly of the circumferential surface of the fastening element assembly and forming the contacting surfaces of said tie bolt and expanding wedge, said tie bolt and expanding wedge each having an axially extending wedging part extending from the first end thereof toward the second end and a second part extending from the trailing end of said wedging part to the second end thereof, the transverse cross-sectional area of said wedging part of said tie bolt increases in area toward the first end of said tie bolt and the transverse cross-sectional area of said wedging part of said expanding wedge decreases in area toward the first end of said expanding wedge, said tie bolt and expanding wedge having an upspread condition where the first end of said expanding wedge is located rearwardly of the first end of the tie bolt and in contact with the second surface of said tie bolt on the wedging part thereof, wherein the improvement comprises that a flange is formed on said tie bolt on the second end thereof with said flange extending circumferentially around and radially outwardly from the first surface of said tie bolt, said flange being approximately C-shaped in a plane extending transversely of the axial direction of the fastening element assembly, said C-shaped flange having a pair of ends each extending outwardly from said tie bolt in the circumferential direction of the first surface thereof at the second end of said tie bolt, in the unspread condition the second end of said expanding wedge is spaced axially outwardly from the second end of said tie bolt, the parts of said flange extending circumferentially outwardly from said tie bolt being in surface contact with the exterior circumferential surface of said wedging part and form guides for said expanding wedge as said expanding wedge is displaced axially inwardly into the borehole relative to said tie bolt, and in the unspread condition the first surfaces of said tie bolt and expanding wedge form a continuation of one another so that the first surfaces of the parts of said tie bolt and expanding wedge disposed in contact with one another in the unspread condition are symmetrical about the axis of the fastening element assembly.