Methods of preparing cast-in-place geopolymer piles using electrical heating wire (130) to provide heat to cure the piles are described. The heating wire (130) can be associated with a reinforcement cage (120) inserted in the pile shaft. Rod-shaped heating units comprising electrical heating wire (130) can be inserted into a pile shaft and can be reusable. Geopolymer piles with high compressive strength can be prepared from mixtures of class F fly ash and aqueous sodium hydroxide by heating the piles with the heating wire to a stable curing temperature for at least about 24 hours.