Abstract: The present invention relates to an admixture composition for the production of lightweight concretes containing polystyrene beads, which comprises a mixture of organic and inorganic substances which consists of the reaction products of polyurethane resin, tetraethyl orthosilicate, a glycol compound, an aromatic vinyl compound containing an unsaturated double bond, preferably styrene, and an inorganic silicate compound and preferably comprises the following components: glycol copolymer type compounds, in an amount of 15-10 w/w %, glycol polymer-silica type compounds, in an amount of 45-50 w/w %, polyurethane-based resin, in an amount of 13-22 w/w % polystyrene in an amount of 2-3% w/w %, and foam glass beads in an amount of 25-15 w/w %, and a) for the production of a liquid product, based on the total mass of the above composition, organic solvents in an amount of 15-20 w/w %, and water in an amount of 10-5 w/w %; or b) for the production of a solid preparation, based on the total mass of the above compositio