Nanotechnologies in Construction: A Scientific Internet-Journal

274–281

Authors: Shigapov R.I., Sinitsin D.A., Khalikov R.M., Solovyeva E.A., Nedoseko I.V.

ABSTRACT: Introduction. The elaboration of foamed eco-friendly gypsum nanocomposites with low specific gravity, high thermal insulation, operational and technical and economic characteristics remains an urgent task. Controlled hardening of gypsum foam nanoassemblers using dry foaming agents is a promising direction in the technology of production of heat-insulating building materials. Methods and materials. The production of a foam gypsum composition was carried out in an ejector-turbulent mixer by mixing a gypsum nanobinder with functional foaming nanoadditives. Building gypsum G5 BII was used as a binder in the work; porization of gypsum compositions was carried out using an adsorbed foaming agent PBNS. Results. The transformation of liquid-phase foaming agents into solid-phase ones by binding water allows the production of gypsum foam compositions from dry mixtures, which gives high dosing accuracy, a good degree of homogenization of components and stable characteristics of foamed gypsum nanocompositions. In production conditions, a one-storey small-sized pavilion was built using a pilot 3D printer AMT S1160, in which vertical enclosing structures are filled with foamed heat-insulating nanostructured foam gypsum. Monolithic foam gypsum nanomaterial with a density of 300–400 kg/m3 was used for insulation and sound insulation of attic floors during the overhaul of the historic building of the Veterans Hospital in Ufa. Discussion. The elaboration of technology for obtaining foam gypsum from dry mixtures is based on the advantage of manufacturing and using thermal insulation nanocompositions, which allows for significant punctuality of dosing and stable characteristics of foam gypsum building materials. Surfactants have a significant effect on the kinetics of the structure formation of the foam gypsum nanocomposition and slow down the coalescence of air bubbles. Conclusions. Nanoporous foam gypsum concrete, obtained as a result of controlled hardening, with a density of 400 kg/m3 has a thermal conductivity of 0.12 W/(m•ºС) and a compressive strength of 1.4 MPa. The compressive strength of foamed foam gypsum using a dry foaming agent on sorbents is 17% higher than the strength of a heat-insulating nanomaterial prepared using traditional technology.

294–299

Authors: Mazitova A.K., Zaripov I.I., Aminova G.K., Ovod M.V., Suntsova N.L.

ABSTRACT: Introduction. For the production of building products made of PVC, compositions are used that, along with the polymer, include additives: plasticizers, stabilizers, modifiers. This leads to a decrease in the chlorine content in the composition and increases the flammability of the productitself. Therefore, nanoparticles of various fillers are added into the compositions. Fillers inPVC compositions (more often inorganic, less often organic substances) are solid additives that differ from the polymer matrix in chemical composition and structure.In most cases, the main function of fillers is to reduce flammability and cut costs of the products obtained, in some cases they serve to impart or improve the following properties: reducing plasticizer absorption, changing in dielectric properties, increasing rigidity and hardness, reducing noise transmission, reducing toxicity of combustion products. Main part. Fillers are classified according to various criteria. According to the state of aggregation, they are divided into gaseous, liquid and solid. By their nature, they are divided into organic and inorganic; according to the source of receipt – reinforcing, strengthening, reinforcing, neutral; bythe size, particle shape and structure – into 4 main types: dispersed (powder); fibrous (fibers, threads, bundles, etc.); sheet (film) with a given structure (fabrics, paper, tapes, sheets, films, nets); volumetric (framework) with a continuous three-dimensional structure (bulk fabrics, felt, skeletal and porous frameworks). The most commonly used solid fillers, which are also called dispersed. The introduction of dispersed fillers into polymer composite materials (PCM) is more appropriate for creating mass-produced materials, more technologically advanced, with a low level of strength characteristics. Dispersed fillers are introduced into thermoplastics with high fracture energy to reduce their cost, increase stiffness and compressive strength, and improve their technological characteristics during processing. At the same time, their tensile strength and impact strength decrease due to reduction in the proportion of polymer in the filled composition. The introduction of solid and hard particles leads to an increase in the elastic modulus (E); and soft, elastic or gaseous fillers – to its decrease. According to the mechanism of action, dispersed fillers can be divided into inert ones, which do not affect the properties of the matrix and are introduced into its composition to reduce the cost of the composition, and active ones. Dispersed fillers are divided into mineral, organic and metal. The commonest of those are minerals. Conclusion. Thus, at present, there are a large number of substances and materials used as fillers and making it possible to obtain PCM with low shrinkage and shape stability of products, high mechanical properties and the necessary set of special properties. Due to fillers, PCM can compete with other materials such as glass, ceramics and even metal in most areas of human activity.

319–327

Authors: Agzamov F.A., Grigoryev A.Y.

ABSTRACT: Introduction. Portland cement slurries (suspensions) used for well cementing have high water-cement ratios (0.45–0.6). They also contain a minimum amount of inert fillers, must have zero water separation and controlled hardening with a minimum time between the start and end of setting. Literature review. Most of the scientific work on the use of nano-additives in binder systems relates to the construction industry. Nanosilicon, nanotitanium, nanocarbonate, nanoclays, carbon nanofibers, etc. were widely used as modifiers of cement systems, which showed an increase in the strength characteristics of the resulting concretes. Literature review showed that there is a very wide range of concentrations of nanoadditives in cement systems from 0.001 to 10.0%. An increase in the strength of cement with high concentrations of additives in a number of publications is explained by a decrease in its capillary porosity due to clogging of the pore space. However, nanoadditives should not play the role of microfillers in the hardened stone. They should work in cement slurry at the stage of cement hydration and cement structure formation at concentrations less than 1.0%. Results and Discussion. The paper presents the results of experimental studies of the rheological properties and early strength of stone based on Portland cement with additives (0.01%) of nanocarbonate and nanoiron. The role of nanoadditives is to increase the rate of cement hydration by reducing the activation energy, and accelerating the dissolution of the solid phase in the liquid. Nanoadditives can be a “substrate” on which two-dimensional nuclei of a new phase are formed. The probability of the appearance of two-dimensional nuclei on the substrate is much higher than for the formation of three-dimensional nuclei of a new phase in the bulk of the solution. Conclusion. The results show an ambiguous effect of additives on the tested parameters, which indicates the need to optimize the amount of additives. One of the reasons for the ambiguity of the results may be high water-cement ratios, which reduce the likelihood of the formation of “constrained” conditions in cement slurries. At the same time, the effects of accelerated cement hydration are “levelled” and the number of contacts between hydration products is reduced