Accelerating admixture for cementitious compositions

A method of accelerating setting and hardening of hydraylic binders, said method comprising:

• adding to said hydraulic binders from 0.01% to 40% with respect to the weight of the binders of a transition metal silicate hydrate having general formula
• aMexOy.bMO.cAl2O3.SiO2.dH2O 1)
• where
• Me represents a transition metal whose molar coefficient a is in a range between 0.001 and 2;
• M represents an alkaline earth metal whose molar coefficient b is in a range between 0 and 2;
• The molar coefficient c for Al2O3 is in a range between 0 and 2;
• H2O represents the hydration water of the silicate hydrate whose molar coefficient d vary within a wide range between 0.5 and 20;
• x and y both be equal to 1 or different, depending on the valence of the transition metal, given that the valence of the oxygen atom in the metal oxide is equal to 2
• and being characterized by the presence of particles with a diameter lower than 1,000 nm,
• whereby accelerating the setting and hardening of said hydraulic binders.