Abstract: The geopolymeric alumino-silicates have been grouped in three families depending on the atomic ratio Si/Al which may be 1, 2 or 3. With the most commonly used simplified notation, a distinction is made between______________________________________ poly M.sub.n --(Si--O--Al--O) .sub.n-- or (M)--PS, (sialate) poly M.sub.n --(Si--O--Al--O--Si--O) .sub.n-- or (M)--PSS, (sialate- siloxo) poly M.sub.n --(Si--O--Al--O--Si--O--Si--O) .sub.n-- or (sialate- (M)--PSDS disiloxo). ______________________________________A process for obtaining a geopolymer of the alkaline poly(sialate-disiloxo) family (M)-PSDS with the ratio Si/Al=3 involves producing geopolymeric resin obtained from a reactional mixture containing:a) an aqueous solution of alkaline silicate with a molar ratio SiO.sub.2 :M.sub.2 O comprised between or equal to SiO.sub.2 :M.sub.2 O 4.0:1 and 6.6:1 the concentration of which is over 60% wt and where the initial viscosity at 20.degree. C.