Cement-polymer materials for well casing

The work shows the efficiency of using the SСADC reagent as an additive in cement-polymer mixtures. It also outlines physicomechanical properties of the cement slurry and the stone formed on their basis at temperatures of 22 C and 80 C. The main regularities of the formation of structures of various levels in cement-polymer solutions are revealed, depending on the degree of filling and the type of introduced modifications of the SСADC reagent. It was found that an entangled fibrous structure is formed between the hydrated cement minerals and the complex additive SСADC. At a concentration of 0.2%, it provides a self-healing effect for a damaged cement stone, and also improves the properties of cement-polymer grouting mixtures, contributing to a decrease in the filtration rate of the solution to 30%, an increase in bending strength by 25-27% and by 36-42% in ultimate strength for compression.

Technology of Production of Binder Modifying Nanoadditives

The article deals with the issue concerning production of a dry nanoadditive. In order to achieve this goal, an aqueous solution of polyvinyl acetate dispersion (PVAD) and nanotubes, or lime slaking nanoparticles is used. As a result of the hydration process heat is released, the polyvinyl acetate emulsion forms particles with nanotubes in their composition. During the study performed an optimal ratio of all components was established: quicklime + PVAD-CNT – 71-73% and 0.01-0.018 CNT; “Megalith” – 21-25%; ammonium salt – 4-6%, as well as the optimal amount of the complex additive, which is in the range of 1-1.5% by weight of calcium sulfate hemihydrate. Later on the resulting nanoadditive can be used to modify binders or other materials

Development of technology and recipes for combined minced fish with food additives

The purpose of scientific research is to develop technologies and recipes for minced fish products with dietary supplements. The objects of research, when obtaining the recipe and technology of model minced fish, were: pollock, cod, wheat bread made from premium flour, and the dietary supplements introduced were oil extract of dried mushrooms, juniper oil extract, coriander oil extract and a complex additive "Moby Lux Universal". Vegetable oil extracts were used as a plasticizing component and additional raw materials containing flavoring substances. The use of additives of plant origin allows you to stabilize the functional and technological properties of raw materials, increase the biological value, emphasize the organoleptic characteristics of the finished product. Oil extracts of vegetable raw materials and "Moby-lux Universal" are rich in minerals and vitamins, dietary fibers, proteins, polyunsaturated fatty acids.

Modification of Cement Matrix with Complex Additive Based on Chrysotyl Nanofibers and Carbon Black

This paper presents the results of studying the properties of cement-based composites modified with a complex additive based on chrysotile nanofibers and carbon black. The optimal composition of complex additive was stated due to the particle size analysis of suspensions with different chrysotile to carbon black ratios and the mechanical properties study of the fine-grained concrete modified with the complex additive. It was found that the addition of chrysotile in the amount of 0.05% of cement mass together with carbon black in the amount of 0.01% of cement mass leads to a 31.9% compression strength increase of cement composite and a 26.7% flexural strength increase. In order to explain the change in the mechanical properties of the material, physical and chemical testing methods were used including IR-spectral analysis, differential thermal analysis, energy dispersive X-ray analysis as well as the study of the microstructure of the samples modified with the complex additive. They revealed the formation of durable hydration products including thaumasite and calcium silicate hydrates of lower basicity that form a dense structure of cement matrix, increasing the physical and mechanical characteristics of cement-based composites.

Effect of Agents of Initiation of Carbonate Biomineralization on Cement Properties

The paper presents the results of the assessment of the effect of bacterial microorganism Sporosarcinapasteurii and CaCl2 and CH4N2O precursors as agents initiating carbonate mineralization processes on the construction and technical properties of binders. In order to achieve this, a preliminary bacterial solution with precursors was prepared, which was introduced into the system instead of mixing water in the range of 0–10% with interval of 2%. The effect of the bacterial solution as a complex additive on the physical and mechanical properties of cement paste and stone is shown: normal density, setting time, water segragation, strength in compression and bending. The introduction of the solution provides a reduction in the setting time of cement without loss of strength both at the initial and at the final stages of hardening.

Cement-Based Materials Modified with Nanoscale Additives

The most common and reliable material without which modern construction is indispensable is concrete. The development of construction production is pushing for new solutions to improve the quality of concrete mix and concrete. The most demanded and significant indicators of a concrete mixture are the compressive strength and mobility of the concrete mixture. Every year, the volume of research on nanomaterials as modifying components of concrete is significantly increasing, and the results indicate the prospects for their use. Nanoparticles with a large specific surface are distinguished by chemical activity, can accelerate hydration and increase strength characteristics due to nucleation and subsequent formation of C–S–H and compaction of the material microstructure. Sol of nanosilica, which can be used instead of microsilica from industrial enterprises, and carbon nanomaterial have a wide reproduction base. This paper presents studies of these types of nanomaterials and the results of their application in cement concrete. Studies have shown that the effect is also observed with the introduction of an additive containing only one type of nanoparticles. The dependence of the obtained characteristics of cement concretes on the content of these nanomaterials has been established. It has been found that the best results were obtained with an additive in which the above-mentioned nanomaterials were used together. Compressive strength of heavy concrete samples, improved by the complex nanodispersed system, was 78.7 MPa, which exceeds the strength of the sample containing the CNT additive in a pair with a super-plasticizer by 37 %. The paper proposes the mechanism for action of the presented complex additive.

Effect of Borosilicate Glass Wastes and Synthetic Silica on Cement Products Properties

This paper presents the findings of research study on the effect of borosilicate glass wastes on properties of cement paste and mortar. The borosilicate glass contains three times less alkali than soda-lime glass and about 12 % of boron oxide, so pozzolanic activity of borosilicate glass is three times higher compared to soda-lime glass. In order to increase the pozzolanic activity of glass precipitated synthetic silica was used. Mathematical models were used in order to test the effect of synthetic silica on pozzolanic activity of borosilicate glass. Test results indicate that replacement of 1 % of borosilicate glass by synthetic silica increased the pozzolanic activity up to 9.4 mg CaO/g of additive. By adding 5 % of borosilicate glass instead of cement, the standard compressive strength is reduced by about 20 %. However, complex additive of borosilicate glass (2–5 %) and synthetic silica (0.5 %) increased initial compressive strength of cement mortars to 10 %.

ADDITIVES FOR HEAVY CONCRETE BASED ON INDUSTRIAL WASTE FROM CHEMICAL INDUSTRIES

The effect of a complex additive containing superplasticizer C-3 on the properties of heavy concrete has been investigated. The efficiency of the plasticizing action of the specified additive at the stage of preparation of the concrete mixture and subsequent molding of concrete products has been revealed. It is proved that at the stage of concrete hardening, the investigated additive promotes to the formation of a more homogeneous colloidal-crystalline structure and the formation of dense crystalline hydrate complexes of cement stone by the time of completion of concrete hardening. The objects of investigation were samples of grade B22.5 concrete without additives; containing a monoadditive - superplasticizer S-3; containing the complex additive. When designing the composition of additives for heavy concrete, we proceeded from the fundamental provisions of construction science that the complexity of the action of additives lies in the optimal combination of two main opposite processes in time and volume of the concrete matrix. The use of the caprolactam oligomer synthesized in the course of this investigation makes it possible to solve the problem of involving concentrated wastes of caprolactam production in the production turnover. The obtained caprolactam oligomers can be used in construction as plasticizers of concrete mixtures, as inhibitors of corrosion of steel reinforcement in the production of reinforced concrete products. Water-soluble oligomers of caprolactam, which reduce the time of dissolution of the superplasticizer C-3 and the dispersion of low-temperature catalyst in the volume of the concrete mixture being mixed, were synthesized. It was found that in the presence of the oligomer caprolactam in an amount of 10 to 20% of the mass. the dissolution rate of S-3 superplasticizer in water at a temperature of 20-21 °C increases by 2.0-2.2 times. This contributes to a better mixing of the components of the concrete mixture, primarily to improve the dispersion of the complex additive in the volume of the concrete mixture. The caprolactam oligomer used in this research work is an effective water-soluble wetting agent for the surface of particles of cement, sand, and crushed stone, which is very important for activating hydration and sorption processes during mixing of a concrete mixture. The increased wetting properties of the caprolactam oligomer are characterized by a wetting angle of 19.6 °.

Hardening Cement Conglomerates by Mining Industries Waste

About 3.5 billion tons of mining waste is generated annually in Russia. The task of their utilization is urgent in connection with the accumulation of large-tonnage waste of simultaneously mined rocks, enrichment waste and crushing screenings. The problem can be solved by using these wastes as mineral additives to artificial cement-based conglomerates. According to the study results it was found, that the compressive strength of hardened cement paste increased during all hardening periods, when finely dispersed mining wastes were introduced. In the early stages of hardening, limestone had a predominant effect. Introduction of diopside led to the greatest hardening together with the hardening period increase. Linear and nonlinear mathematical models, describing the dependence of cement strength on the type and amount of mineral additives, were constructed. The highest strength values of hardened cement paste, both after hardening under normal conditions for 28 days, and after heat and moisture treatment could be achieved with 7% dispersed diopside. At the same time, the hardening effect (increase in the strength of cement by 35–40%) was retained when 1/3 of the diopside in the complex additive was replaced by dispersed limestone. An increase in the content of limestone in the complex additive composition over 1/3 was impractical.