The invention relates to a composition which comprises at least one liquefying agent for a hydraulic composition and at least one aminoalcohol, selected from the group consisting of 2-amino-2-methyl-1-propanol and N-aminopropyl-monomethyl ethanolamine. The invention also relates to the use of said composition for reducing corrosion, especially on steel formwork in precast components or on concrete steel of concrete constructions.