The paper presents the study of the influence of complex additives on strength properties of cement concrete. Complex nanostructured additives from various components containing nanosized particles received through the laboratory study are used in experiments. High strength of fine-grained concrete is obtained. The optimum concentration of additives of nanostructured mineral components together with superplasticizer thus ensuring high strength is established. The study shows that the developed nanostructured complex additives increase early and design strength, improve mobility and can be used in the production of self-compacting construction concrete.

The paper presents the measured data on interfacial tension of bentonite suspensions and strength of a cement stone in water solutions of Frem Giper S-TB superplasticizer. The interfacial tension of water-surfactant-bentonite suspension is experimentally measured at various concentrations of a bentonite solid phase. The dependence of interfacial tension on the concentration of a solid phase is quite complex. In particular, the minimum is observed on interfacial tension isotherms at 3 wt.% of bentonite. Isoplastic cement mixes are obtained from the above suspensions. The cement stone samples are made of these mixes. The strength test of these samples showed a considerable increase of the compression strength. At the same time, 3 wt.% of bentonite demonstrated the maximum increase in strength.

The paper presents the results of research on creating a high-strength cement composite using a complex additive. The optimal concentrations of additives of the Odolit-K hyper plasticizer in combination with bentonite have been determined. A significant decrease in the w / c ratio and an increase in the cement stone's strength was obtained. High-strength cement composites have been obtained with the optimal content of the complex additive. The volume-weighted average crystallite sizes were calculated using the Scherrer formula on the basis of X-ray studies. Deformation diagrams of statically loaded samples of prisms of the basic and control compositions of high-strength concrete were obtained. Deformation diagrams are investigated.

Surface and structural properties of the cement stone were studied using a complex nanostructured modifier. The surface properties of mixing water with surface-active substances in combination with nanoparticles of bentonite deposits of the Chechen Republic were investigated. The surface tension isotherms were presented. Compositions of complex nanomodifiers reduce surface tension of mixing water. The study on physicomechanical properties of the cement stone with complex nanomodifiers showed an increase in mechanical strength and density. Optimal concentrations of complex nano-modifiers affecting cement composites and their rheological properties were identified. The relationship between surface tension and density of the structure of cement stone was established. Based on the X-ray diffraction patterns obtained using the Selyakov-Scherer model, the sizes of crystallites were calculated.

The paper presents the most optimum concentration of crushing dust of concrete scrap (CDCS) ground in the laboratory spherical mill to a specific surface of 4000 cm2/g for further replacement of a part of cement. High strength parameters are achieved at partial replacement of cement with various concentrations of CDCS obtained from concrete fragments of reinforced concrete plates produced in 1976. X-ray phase analysis of cement stone samples obtained using 30% of CDCS instead of cement separately and together with Odolit-K and Frem Giper S-TB superplasticizers in 1, 7 and 28 days of hardening in normal conditions is used. The morphology of a cement stone surface with the use of CDCS and superplasticizers in various periods is studied.Keywords-crushing dust of concrete scrap, superplasticizers, Xray phase analysis, cement stone surface.I.