Construction Materials

The article characterizes Jurassic mudstones of the North-West Caucasus as a potential raw material for the production of clinker tiles with water absorption of less than 3%. It is noted that traditional for the south of Russia raw materials for the production of ceramic bricks and tiles in the last centuries were various types of loams, which are widely distributed almost throughout the territory. However, for a number of reasons, they cannot be considered as raw materials for the production of clinker tiles, for which there has been a steady demand in recent years, especially on the Black Sea coast. Geographically, the Jurassic sediments in the Krasnodar region are traced in a wide strip (50–100 km) at a distance of 20 to 60 km from the coast. These are the oldest rocks in the region. The thickness of numerous mudstones varies from a few to many tens of meters. The chemical composition of mudstones is characterized by the content of aluminum oxide from 17 to 22 %, increased content of potassium oxide and iron oxides. The mineral composition is represented by hydrous mica, kaolinite and chlorite with admixture of quartz and feldspars. Pre-firing properties of argillites can be regulated by the degree of grinding. In terms of sinterability, argillites are qualified as a strong-medium sintering raw material of low-temperature sintering with high strength of ceramic stone. The results and analysis of the obtained data allow us to assert that the Jurassic mudstones of the North-West Caucasus are potentially suitable raw materials for production of clinker tiles with a wide range of physical and technical properties using a simplified technology.

There are several models in which the corrosion rate, rust expansion, and resulting crack propagation around reinforcement can be assessed. The effect of crack-induced corrosion on the behavior of the structure can also be assessed. Several methods have been proposed to evaluate the mechanical performance of reinforced concrete structures with corroded reinforcing bars. Changes in the mechanical properties of reinforcing bars, concrete and their interactions need to be modeled based on the concept of analytical methods. The load-bearing capacity of reinforced concrete beams with reinforcement corrosion was calculated using the finite element method. The influence of reinforcement corrosion is considered from the point of view of changes in the mechanical properties of reinforcement and adhesion of reinforcement to concrete. Instead of reducing the cross-sectional area of the reinforcement, the Young’s modulus and yield strength of the corroded reinforcement are reduced. Numerical modeling of the structural performance of reinforced concrete structures with reinforcement corrosion using a finite element program has shown that modeling of structural deterioration, such as reinforcement corrosion and concrete cover cracking, sometimes has a large impact on the analytical results. The structural characteristics of reinforced concrete elements with reinforcement corrosion are calculated. Using this modeling method, an analysis of the degree of influence of corrosion on structural characteristics was carried out.

To prevent biofouling of cement stone and its damage by fungal microorganisms, it is proposed to introduce 0,5 wt. % calcium stearate into the cement mixture. To ensure volumetric hydrophobization of cement stone, the additive is crushed to nanoparticles. The cement stone was cured in the air for 28 days. To study fungal corrosion, the surface of the cement stone was treated with a suspension of pores of Aspergillus niger fungi. The hydrophobic surface of the cement stone was not biofouled by fungal microorganisms Aspergillus niger during 6 months of the samples being in a humid environment, and black mold foci developed on the surface of ordinary cement stone during this period of time. The action of fungi and their waste products caused a decrease in the amount of calcium in the cement stone by 9 %, and had no effect on the hydrophobized cement stone. Due to the immunity of cement stone with a hydrophobizer to the action of microorganisms and water, free calcium hydroxide is not removed from the structure, but some amount is washed out of the surface layer and the pore liquid. A significant slowdown in mass transfer in cement stone under the action of liquids is provided by the hydrophobicity of the surface of cement stone and the walls of pores and capillaries, imparted by calcium stearate, as well as partial colmatation of the pore structure by means of the introduced additive.

The improvement and creation of new production technologies is largely determined by the level of innovation in the field of materials science. In this paper, the experience of practical implementation of innovative building materials and products made of light steel thin-walled structures in the real sector of the economy is considered. Suggestions are given for possible use in state programs for the restoration and development of new territories of Russia. The problem of economic recovery, creation of new jobs, implementation of development programs for specific subjects of new territories can be solved by consolidating the subjects of the Russian Federation and forming professional construction teams on the basis of specialized enterprises of the subject of the Russian Federation for the implementation of state programs. The authors, if necessary, offer services for training and transfer of scientific and technical knowledge to Customer specialists at the place of construction of prefabricated facilities.

The results of the study of the effect of industrial fireproofing compositions on the weight loss of samples of solid pine and aspen wood during combustion are presented. Fireproofing compositions of different brands was introduced in the form of ready-made solutions (with a consumption of 500–600 g/m²) by impregnation of test samples of coniferous and deciduous wood. It has been established that, from the point of view of mass loss during combustion fireproofing compositions have different efficiency: the best of them provided I group of fire retardant efficiency. For a comparative assessment of the effectiveness of the use of various industrial flame retardants, the method of analysis of variance was used. The hypothesis about the effect of interaction between the type of wood and the grade of OS was tested, and the significance of the influence of factors on the weight loss of samples during combustion was assessed. It has been established that the effect of interaction between the type of wood and the type of fire retardant composition is 3.51 times greater than the effect of the type of wood, which is due to both the structural differences between aspen and pine wood, and the unequal absorption of OS of different operating principles into the outer layers of the wood material. It was determined that the degree of influence of the type of wood (aspen, pine) on the loss of mass of wood material during combustion is 62.3 times less than the influence of the type of fire retardant composition.

Filtration of suspensions and colloids in porous materials occurs during the construction and operation of hydraulic structures, tunnels and underground storage facilities. Filtration models are used to calculate the penetration of grout into loose soil, when treating drinking water and industrial wastewater. During the filtration process, suspended particles pass through large pores and get stuck at the entrance of small-diameter pores. The trapped particles form a stationary deposit. A model of filtration of a polydisperse suspension in a porous material is considered. The purpose of the work is to study sediment profiles – the dependence of the concentration of deposited particles on the distance to the porous material inlet at a fixed time. An exact solution to the model was constructed using the method of characteristics. It has been shown that when filtering a polydisperse suspension, the distribution of sediment differs for different types of particles. The sediment profile of the largest particles always decreases monotonically, but the sediment profile of the smallest particles is not monotonic. It decreases at short times, then a maximum point appears on the graph, moving along the porous medium as time increases. After the maximum point reaches the porous material exit, the sediment profile becomes monotonically increasing. The sediment profiles of intermediate size particles and the total sediment profile are either monotonic or non-monotonic depending on the model parameters. The behavior of maximum points of non-monotonic profiles has been studied.