The paper presents data on the study of the polycondensation of 2-furaldehyde and 1,3,5-trihydroxybenzene in an alkaline medium to obtain a plasticizing additive. Results are presented on the study of the products of the separate interaction of 1,3,5-trioxybenzene and 2-furaldehyde with NaOH, and the joint polycondensation of 1,3,5-trioxybenzene with 2-furaldehyde with NaOH by UV spectroscopy. The structure of the product of the interaction of 1,3,5-trioxybenzene with 2-furaldehyde in an alkaline medium was studied by IR spectroscopy. Stronger C–H bonds appear in the IR spectrum and stretching vibrations of the C = O group are not observed, which confirms the production of a new compound. The optimal dosage of the developed plasticizing additive has been established as 0.3% of the cement mass (calculated on dry matter). The developed plasticizing additive can significantly reduce the water-cement ratio while maintaining the strength characteristics of cement compositions. In addition, when using the additive, the strength characteristics are significantly increased with a reduced water-cement ratio.

The paper presents data on the synthesis of phloroglucinol-furfural modifier (1,3,5-trihydroxybenzene-2-furaldehyde oligomer) based on 2-furaldehyde (furfural) and 1,3,5-trihydroxybenzene (phloroglucinol). The synthesis of a modifier with different molar ratios of phloroglucinol/furfural was carried out. It was found that an increase in the molar ratio leads to an increase in the plasticizing ability of the modifier. The optimal concentration of the catalyst was determined to be equal to 50% by weight of phloroglucinol. Two chemical forms of the modifier were obtained: H-form and Na-form. The structure of various forms of the modifier has been studied by scanning electron microscopy. It was found that the oligomers used in the work for the synthesis of the modifier, in addition to 2-furyl methyl alcohol, do not have plasticizing properties. Purified 2-furyl methyl alcohol has weak plasticizing properties. It is shown that to achieve the best plasticizing effect, it is necessary to gradually introduce a condensing agent into the reaction mixture. With gradual introduction, a complete condensation reaction occurs between the monomers, which affects the improvement of the plasticizing properties of the resulting product. The spread of the cement mixture when using 0.3% of the additive based on the mass of cement in terms of dry matter is 19 cm.