Patent ID: 8556558

Claim:
A fastener for use in a cementitious material, said fastener comprising: a shaft comprising a first portion having a first shaft outer surface, a first shaft inner surface and a first shaft outside diameter and a second portion having a second shaft outer surface, a second shaft inner surface and a second shaft outside diameter, said shaft having a longitudinal void therein, a longitudinal axis and two ends; a shaft thread that is attached to said first shaft outer surface and said second shaft outer surface, said shaft thread having a variable shaft thread outer diameter with a maximum extent; a tip that is attached to one end of said shaft, said tip having an upper tip outside diameter that is greater than said second shaft outside diameter, said tip comprising tip threads that are self-centering and self-setting, said tip threads comprising a plurality of thread members that are substantially triangular in cross section and that surround a substantially conical space that is in communication with said longitudinal void; and a head that is attached to the other end of said shaft.