Abstract: Forming concrete piles with an enlarged base for structural foundations for buildings. The invention involves: a) drilling a bore hole with an auger; (b) pumping fluid concrete into the bore hole through a channel in the auger whilst retracting the auger from a lower portion of the bore, such that the lower portion of the bore becomes filled with a volume of fluid concrete; (c) applying a pressure to the volume of fluid concrete by at least partly reinserting the auger into the lower portion of the bore, such that the applied pressure causes the volume of concrete to expand radially, thereby increasing the diameter of the lower portion of the bore; (d) retracting the auger from the remainder of the bore whilst pumping further concrete into the bore, such that the bore fills with concrete and forms a concrete pile with an enlarged base. The enlarged base area provides greater load bearing capacity.