Abstract  The development of the hydration-hydrolysis processes in the 3CaOSiO₂-H₂O system is studied by X-ray diffraction in presence of varying contents of a new plasticizer, belonging to the lignosulphonates class. The influence of the additives upon these processes with increasing time is observed and it is shown to depend on the nature and content of the additives and the reaction time. This influence of the additives on the kinetics of the hydration-hydrolysis processes, retardation or acceleration, is due to the strong adsorption of these admixtures on the surface of the anhydrous or partially hydrated particles of the system. The influence of the additives also appears during the development of the formed hydrocompounds according to structure and composition. As a result of these complex actions provided in the forming system (3CaOSiO₂-H₂O), the mechanical strength is favorized mainly by certain proportions of plasticizer admixtures (0.1% LSC and 2% ADCOM).