Abstract: An anchor is provided that is inserted into a bore in a cementious member, the bore having a side wall. The anchor is made up of an elongated stem having a longitudinal axis and a leading end and a trailing end. A tensioning head is disposed at the leading end of the stem and connected to the leading end of the stem in such a manner that when the stem is moved along its longitudinal axis the tensioning head moves with the stem. The tensioning head also has a leading end, a trailing end and an outer surface, the leading end of the tensioning head being wider than the trailing end of the tensioning head and the outer surface of the tensioning head flaring generally outwardly from the trailing end to the leading end of the tensioning head.