Introduction. Faster construction and commissioning of industrial and civil facilities is a main factor affecting their operational characteristics at the stage of construction due to high-quality multifunctional additives, having plasticizing properties, coupled with the accelerated curing of composite materials in cement binders. The article addresses a study on the influence of a new multifunctional additive on the physical and mechanical properties of heavy concretes, that determines its plasticizing properties and affects concrete strength. Materials and methods. The study focuses on concrete B30. The Vicat apparatus was used to test the cement paste to identify its normal density and setting time according to GOST 310.3. The strength of cubic specimens was tested using hydraulic press P-120 according to GOST 1080-90. Results. The multifunctional additive was obtained by synthesizing caprolactam mixed with polyalkylene glycol and amino alcohols. The test on the setting time of the cement paste has proven that the multifunctional additive plasticizes, if added to heavy concrete mixes. The impact of the concentration of the multifunctional additive on the setting time, compressive strength and slumping of the concrete mix has been identified. These new data were applied to find the optimal interval of concentrations of the multifunctional additive, added to the concrete mix to make densely reinforced concrete products. The optimal concentration interval is 0.2–0.3 % of the cement mass. Conclusions. The multifunctional additive made of domestic chemical products as a result of the study, improves physical and mechanical characteristics of concrete mixes to be used in the construction of civil and industrial construction facilities.

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This paper presents the fractionation of PA-6 obtained at temperature below its melting point. Unfractionated samples and polymer fractions were studied by viscosimetry, thermogravimetry (TG, DTG) and differential scanning calorimetry (DTA). It was shown that at the first step of synthesis the polymer is formed with a predominantly linear structure and high parameters of thermal properties. At the second synthesis step the molecular weight of the polymer and its thermal properties increase and subsequent demonomerization-drying is accompanied by a further increase in the polyamide molecular weight.

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