Taking into account the environmental problems associated with the production of Portland cement (PC), in recent years the use of Fly Ash (FA) in the production of concrete has been promoted. The use of fly ash has been possible through the activation with Portland cement and as a geopolymeric cementitious material. In this paper, a third activation technique for fly ash, known as electrometagenesis, was investigated. This treatment consists in the activation of fly ash after the migration of ions from an external alkaline solution, by applying an electric field across the hardened concrete. As a source of alkaline ions, solutions of sodium hydroxide and sodium silicate with various molar ratios were used. After finishing the treatment, the variation in the compressive strength, the ultrasound pulse, and the microstructure of concrete matrix were evaluated. Results showed that the alkaline ions migrated into the concrete matrix, reacted with fly ash, and mutated in new phases, producing an improvement in their physical properties.