Expert work has been carried out to establish quality indicators for three types of concrete paving slabs: "Auriko", "Paving stone", "New City". The tests were carried out on selected samples in accordance with GOST 17608-2017. According to the test results, it was determined that only the samples of "Paving stones" tiles meet the requirements of GOST, other types of tiles revealed non-compliance of the studied samples with GOST 17608 in terms of water absorption and frost resistance.Frost resistance tests for Aurico and Novy Gorod product samples were interrupted after 15 freeze-thaw cycles due to the destruction of the samples.

Keywords: paving slabs, concrete, compressive strength, frost resistance, surface defect "sink"

The results of studies of the effect of mineral additives of natural and man-made origin on some properties of fine-aggregate concrete with the introduction of a mineral additive from 10 to 25% of the cement weight instead of either a part of cement with an increase in the value of W/ C, or a part of sand with a constant value of the value of W / C are presented. A slight, up to 3%, change in the average density of concrete was revealed. A decrease in the E-modulus from 4 to 14% was recorded when replacing a part of cement, while an increase in the flexural strength, depending on the dosage, was up to 26% (marshallite) and 6% (chemical water treatment sludge), and a decrease in the compressive strength was from 10 to 22%. When replacing part of the sand, an increase of up to 10% of the E-modulus, the flexural strength from 19 to 38% (marshallite) and up to 11% (chemical water treatment sludge) was recorded. The increase in the compressive strength, depending on the type and dosage of the additive, ranged from 8 to 20%. No significant effect of additives on the porosity of cement stone was revealed.

Keywords: mineral additive, fine-aggregate concrete, flexural strength, E-modulus, shrinkage, water absorption

A method of selecting admixtures for the production of dry building mixes is proposed based on the results of an expert assessment of the complex indicator of the workability of application (connectivity, continuity when pulling with a toothed trowel, elasticity, quality of rollers) on a 100-point scale and the strength of adhesion to the concrete base, followed by the calculation of the specific cost of admixtures in the mixture per ton of products, respectively, by one point of workability of application and 1 MPa of adhesion strength, developed as a result of studies of adhesive mixtures made using 4 different cements, 5 water-retaining additives and 12 redispersible polymer powders. The possibility of obtaining adhesive compositions of adhesion class C 2 using redispersible polymer powders of domestic production is shown.

Keywords: dry building mix, adhesion strength to the base, unit cost, processability of application

The synthesis of nanocomposite FeNi3/C based on the PAN, FeCl3 · 6H2O and NiCl2 · 6H2O, whereby the first time by the IR heating at 400 ÷ 700 ° C obtained nanocomposite FeNi3/C FeNi3 particle size of 10 to 80 nm are uniformly distributed UM. Using thermodynamic calculations based on the minimization of the Gibbs energy, confirmed the synthesis of nanocomposite FeNi3/C at T=400 ° C reduction of Fe and Ni with H2, produced during the process of carbonization of polyacrylonitrile with infrared heating. Designed as a nano material of the films can be effectively used as a carrier material for a magnetic information recording superdense. Recording density is achieved in such a carrier (85-100) Gb/dyuym2. ​

Keywords: nanocomposite, polyacrylonitrile, infrared heating, recording information, the magnetic properties, the carbon matrix

The article briefly describes the history пояявления hydrophobic cements. Considered one of the прспективных directions for the use of water-repellent additives today - in the dry construction mixtures and confirmed the significance of this direction. The article describes the results of experiments on the impact on the indicators of a cement-sandy solution additives series GMI and the analysis of the received data  

Keywords: hydrophobic cement, hydrophobic additives, dry construction mixtures, porosity of a cement stone, strength cement-sandy solution, involving air, antifoam, antifoam agent