As a result of artificial carbonization of slag, construction materials can be obtained. For this purpose, a technology has been developed for producing durable construction products as a result of accelerated carbonization of slag minerals with carbon dioxide (CO2) at elevated pressure (up to 2 MPa) and temperatures (20-60°C). The carbonates formed during the carbonization reaction act as a binder, sticking the slag particles together. Carbonized compacts after autoclave processing have technical properties equivalent to conventional concrete products made on the basis of Portland cement. The technology was developed in laboratory and production conditions by optimizing the parameters of the technological process (pressing force, temperature in the autoclave chamber, carbon dioxide pressure in the autoclave chamber and carbonization time) taking into account the increase in compressive strength and frost resistance of the samples.

Keywords: small-sized products, binder, preliminary preparation, steel slag, pressing, accelerated carbonization, minerals, carbon dioxide, strength, frost resistance

The active use in the production of building materials of waste after the renovation of housing is a relevant and promising direction. the load on logistics for the supply of inert materials is reduced, landfills and waste storage sites are being destroyed, and the cost of building materials from recycled materials is being reduced. The use of recycled clay bricks allows to solve the problem of solid waste disposal, but also to reduce the environmental damage caused to the environment by mankind from the excessive development of natural resources. Finely ground brick cullet has pozzolanic properties and can be used as an additive in a cement mixture, and a large fraction is used in aggregates of cement compositions.

Keywords: Сlay brick scrap, renovation, preparation, pozzolanic activity, hydraulic activity, binder, hardening, aggregate, mortar, strength

A study was made of aggregates used for the production of decorative concretes. Since slabs of these concretes are planned to be used for floors and platforms that are subject to high mechanical stress, aggregates must have the necessary properties. The resistance of crushed stone to impact on a copra, abrasion in a shelf drum and frost resistance were studied. For sands used as aggregates, such characteristics as granulometric composition, particle size modulus, stability of the stabilized mixture, etc. were determined. According to the results obtained, aggregate samples were determined that are most suitable for the production of decorative concrete, which are used for the installation of decorative floors and platforms.

Keywords: wear-resistant materials, decorative effect, size modulus, crushed sand, crushed stone

The aim of the work is to study the possibility of using mineralized fiber as a damping additive in the production of paving slabs and curbs. Fiber mineralization was carried out with an electrolyte solution and sodium silicate. An assessment was made of the physical properties of fiber and their influence on the physical and mechanical properties of fine-grained concrete, hardening both under normal conditions and after heat and moisture treatment. It was revealed that the strength of concretes modified with fiber and hardening under normal conditions is higher than concretes that have undergone heat and moisture treatment by 4.2%.

Keywords: fiber, organic compounds, sugars, cement clinker, blocking, hardening, hydration, strength, paving slabs

Hardening of concrete in the conditions of a construction site under constantly changing temperature and humidity conditions does not provide the desired performance properties of concrete and reinforced concrete structures. An assessment was made of the influence of the conditions of hardening of concrete samples at a water-cement ratio (W / C) of 0.45 and a hardening of 28 days. The hardening of concrete samples took place under conditions of a normal hardening chamber (air temperature T = 20 ± 50С, humidity W = 90 ± 2%), samples in water when completely immersed in a bath at water temperature T = 20 ± 30С and samples immersed in a plastic bag , hardening in the conditions of the air environment of the laboratory (T=20±50C). The samples gain the greatest strength when hardening completely immersed in water, and the smallest when hardening in an insulating polyethylene sheath.

Keywords: concrete scrap, fractionated crushed stone, water-cement ratio, hardening conditions, clinker hydration, strength development kinetics, moisture migration

The hardening of steel-making slags is slow and the strength properties of the cement stone do not provide the specified operational properties. By creating an optimal composition (steelmaking slag + blast furnace) and chemical activation, a composite material with high strength is obtained. The compressive strength of concrete samples at the age of 28 days of hardening in a normal hardening chamber is 28 to 54 MPa. Caustic soda and sodium silicate were used as a chemical activator of hardening. The greatest strength is provided by the ratio of chemicals as NaOH: Na2 SiO3 × nH2O = 1: 1 and at a dosage of 8% of the mass of the composite slag-alkali binder. The optimum ratio of ground granulated blast furnace slag and steelmaking slag is 3: 1 to obtain high compressive strength and minimum water absorption in the early stages of hardening.

Keywords: steelmaking slag, blast furnace slag, homogenization, hardening activator, hydration, strength

The purpose of the study is to determine an effective modifier of the structure of a slag-alkaline stone, characterized by a low value of linear shrinkage and a decrease in cracking in the early stages of hardening. Ground blast furnace slags were activated with aqueous solutions based on sodium silicate and caustic soda. Fly ash and zeolite-containing clay were used as modifiers of the cement stone structure at a dosage of 5, 10 and 15% of the binder consumption. The results of the study showed that an increase in fly ash content does not significantly affect the setting time. The use of zeolite-containing clay as a slag-alkali binder modifier makes it possible to regulate the setting time of the binder at a dosage of more than 10%. Cracking of the slag-alkaline matrix was observed only for mixtures without fly ash and zeolite-containing clay.

Keywords: cement stone, slag-alkali binder, hardening activator, structure modifier, fly ash, zeolites, shrinkage, cracking

The production of Portland cement can be characterized as harmful to nature and human society, resource and energy consuming. The use of by-products of metallurgical and chemical production in obtaining a hydraulic binder is a relevant and promising direction. binder for strengthening and stabilizing the soil of the road base The article investigates the regularities of the initial hardening processes of finely ground slag occurring during structure formation as a result of activation with alkaline solutions and sodium silicates.

Keywords: granular slag, normal density, setting time, activation, awakening of hydraulic activity, binder, hardening

The nature of cathodic reactions occurring during intergranular corrosion (ICC) on stainless steel 08X18H10T in a solution of 0.5 M H2SO4 + 0.01 M KCNS is considered. Evaluation of the thermodynamic potential of various reactions with components of the solution showed that the ICC process in this system proceeds with mixed oxygen-hydrogen depolarization. When the temperature rises, an intensification of the cathode process occurs, which is associated with a decrease in the overvoltage of the reduction of oxidants. Forced medium movement at low temperatures also facilitates the cathodic process, and at elevated temperatures the effect of convective medium movement decreases. This is due to the decrease in the proportion of oxygen involved in the cathode process, since its concentration in solution increases with increasing temperature.

Keywords: intergranular corrosion, stainless steel, temperature and hydrodynamic conditions

The authors have developed a device consisting of a system of perception of images of printed characters and a personal computer (PC), which determines the types of characters. According to the program developed by the authors, the PC contours the image of the printed symbol in a rectangular matrix consisting of the cells of the PC's storage device. As a result of the edging of the shape of the printed symbol, essential and necessary signs were determined - the directions of the elements of the shape of the symbol, according to which, using the developed algorithm, the PC determined the type of this symbol relative to others. The perception system includes a small-sized television tube - a vidicon with a generator of sweeps of a vidicon beam on its screen vertically and horizontally, two channels and a coincidence circuit. The developed system of perception is distinguished by: simplicity of design, compactness, efficiency.

Keywords: direction, perception system, trigger, amplifier, pulse counter, coincidence circuit

Considered the work to be undertaken during the reconstruction of the road network of the city of Penza, and, in particular, the viaduct over the river Sura. The analysis of the major defects giving rise to the reconstruction of the bridge. Presents the main decisions and the progress of the works themselves.

Keywords: the bridge span, corrosion, bearing capacity, pile wrap