A description is given of particle compositions of polysaccharides and/or polysaccharide derivatives and at least one synthetic polymer and if appropriate other aids, characterized in that I. the particles contain a plurality of solid phases, II. the solid phase of the synthetic polymer being contained in the solid phase of the polysaccharide and/or polysaccharide derivative. Likewise a description is given of a process for producing these particle compositions and also of their use in construction material mixtures, for example mortars, plasters, fillers or thin-bed adhesives.