This article presents the results of an investigation of the proposed method and the influence of a modified additive on foam concrete properties. X-ray diffraction analysis showed that the modified additive has a variable mineralogical composition, and the joint use of the components contributes to the synergistic effect, improving the processes of cement hydration. Microscopy of the foam concrete samples showed the presence of microcracks and micropores in samples both with and without the additive. However, the use of the additive significantly reduced their number and size, which indicates an improvement in the structure of the material. The strength values showed that the samples with the additive have high strength. In particular, the strength values of samples of type 3 at different stages of curing exceed those of samples of type 1 by 1.32–1.51 times and samples of type 2 by 1.07–1.10 times. The obtained strength values are 2.82–3.21 MPa for type 1, 3.64–4.04 MPa for type 2, and 4.39–4.84 MPa for type 3, which corresponds to grade D600. The evaluation of water absorption also confirmed the advantages of the proposed method and the additive, significantly reducing the water absorption of the samples and increasing their hydrophobicity. The obtained values of water absorption are 13.8–16.6% for type 1, 13.7–16.1% for type 2, and 9.5–11.2% for type 3.

The paper presents the results of the study of the proposed type of variable profile piles. The proposed type of piles is reinforced concrete driven piles segmented in length. Each subsequent section has a radial displacement along the axis of symmetry relative to the previous section. The positive effect of the performance of the proposed pile is to change the nature of the lateral contact of the pile with the soil, and to increase the drag of the soil. The conducted research is aimed at solving the problem related to the relatively low bearing capacity of traditional square section piles. The research was carried out by the method of model tests of piles on a test bench (tray) at a scale of 1:10. The tests were performed for variant pile types in comparison with a standard square section prismatic pile. The adopted dimensions of the pile model allow the use of this tray without the influence of its boundary conditions on the stress-strain state of the soil. A total of 42 tests were performed, 3 tests for each type of piles compared. Evaluation of pile bearing capacity was performed by static loading of pile models with vertical indentation load until failure. According to the results of the investigations, the resistance values of the compared pile types in the soil were obtained, as well as the dependence of bearing capacity changes on the section dimensions and on the rotation angle. According to the results, the optimal pile solution was selected. The bearing capacity of the proposed optimal pile solution exceeds the bearing capacity of the standard driven pile by 22 %. The results obtained allow us to conclude about the influence of the technological solution of the proposed pile type on its serviceability in soil conditions

The article presents studies of the use of plasticizing additives in combination with fine aggregate (microsilica) and CaOH quicklime for the production of foam concrete. The research will determine the effect of plasticizing additives and active fillers on the properties of foam concrete during their production. The main issue in the production of foam concrete is the time of setting, as their increase leads to shrinkage of foam concrete mixture and as a consequence of the uneven structure of the material. Therefore, the use of plasticizer additives in the production of foam concrete is not recommended. Plasticizer, as a surface-active substance, increases the setting time of the cement binder. However, examining the features of micro silica in combination with caustic lime and plasticizer was found to reduce the time setting. Laboratory studies have shown that the use of these components will produce foam concrete with the projected density, with a uniformly distributed pore structure, high strength, and frost resistance. According to the results of the study, the influence of the number of additives components on the qualitative characteristics of foam concrete was determined, and the optimal composition of the components, plasticizer additives, micro silica, and caustic lime was selected.