Development of Dry Sand-Lime New Multicomponent Mortars into the Historical Cultural Monuments Applied on Local Raw Basis

The visual and instrumental research of the technical condition of historical cultural constructions and their stone additions, documentation of their existing damages, as well as complex development and implementation of further collapse preventing measures and construction durability ensuring measures are presented. Application of processed sand-lime complex mortars based on local raw is offered for blockage of composition cracks during the rehabilitation work taking into consideration some averaged indices of Mape Antique I, Italian “Mapey” firm, similar injection mortar orientation basic characteristics (physical and mechanical characteristics, leakage, viability) and complete laboratory detailed examination results of the component mineralogical and physical and mechanical characteristics of the substances originally used in the construction. The data on local based raw processed sand-lime construction complex mortars (blockage mortar, injection mortar) physical and mechanical characteristics, thermographic dilatometric properties dependence on composition and fastening conditions of mortars are presented

THE INFLUENCE OF FORCED CARBONIZATION ON THE PROPERTIES OF GYPSUM-LIME SYSTEMS BASED ON SECONDARY RAW MATERIALS

the use of secondary raw materials for the production of building materials is a modern trend in solving environmental problems. In the Republic of Crimea, dumps of secondary raw materials – phosphogypsum and lime dust – have accumulated in large quantities at various enterprises. The analysis of phosphogypsum, which has been in the dumps for more than 5 years, showed that by its quality indicators it can be attributed to the 2nd grade in accordance with GOST 4013-2019, and the specific effective activity of the material (Aeff) corresponds to the I class of materials, which makes it suitable for the production of gypsum binders. Prototypes-cylinders were made from a mixture of phosphogypsum with lime dust of 1:1 composition at a pressure of 30 MPa and then subjected to hardening according to three schemes, in order to separate the passage of various types of hardening and study each of them for the physico-mechanical properties of the resulting material. The analysis of experimental data made it possible to establish the effectiveness of simultaneous flow in the system of two types of hardening – carbonate and hydration for lime and phosphogypsum components of the raw mixture, respectively. As a result of the organization of a mixed type of hardening of gypsum-lime binder, samples with a compressive strength of 26.5 MPa and a softening coefficient of 0.63 were obtained within 90 minutes. The calcium carbonate formed in the process, which is the product of the reaction between calcium hydroxide and carbon dioxide, significantly increases the water resistance of the hydration products of gypsum binder. It is established that with an optimal combination of technological factors and hardening conditions, a significant increase in the physical and mechanical characteristics of the carbonized material is possible in a short time.

Design, Simulation and Optimization of an Additive Laser-Based Manufacturing Process for Gearbox Housing with Reduced Weight Made from AlSi10Mg Alloy

The gas turbine engine's (GTE) development aims for the increasing the efficiency, strength, reliability and safety of its components. To create competitive engines, housing parts and components with high functionality and reduced weight are needed. Especially difficult in the design and production are the gearboxes for aviation GTE. Traditional technologies based on precision casting or material forming operations have significant limitations due to the complexity of fulfilling multiple different requirements. Nowadays, one of the progressive production techniques is additive manufacturing. The article presents the results of computational and experimental studies that substantiate the applicability of laser additive technology to reduce the mass of body parts by up to 15% while ensuring their strength properties. The physical and mechanical characteristics of aluminum alloys acceptable for the manufacturing of housing parts were analyzed. The necessary characteristics of the powder alloy of the Al-Si system and the technological parameters of the L-PBF of the modified housing of the gear reducer are established. Using the finite element method (FEM) the L-PBF process was numerically simulated and the technological modes for synthesis of the AlSi10Mg alloy powder were optimized. With the help of a serial 3D printer ProX320DMP, the prototype of a gear housing was manufactured.

Study of the influence of diamond-like carbon film deposition technology on the change of its physical and mechanical characteristics

The paper presents the results of testing the technology of deposition of diamond-like carbon films on the surface of stainless steel substrates at different process parameters, a quantitative assessment of the sp3 bond content and the physical and mechanical characteristics of the coatings obtained, a conclusion about the influence of the deposition process technological parameters on these characteristics is formulated.

Conceptual Approaches to Solving the Issue of Reinforcing the Rock - Cut Structures of Geghard Monastery Complex

The article presents a visual and instrumental research of the technical condition of the main rock-cut structures and their masonry additions, the documentation of their damages (cracks, crevices, destructions and erosions) and deformations, thorough complete laboratory studies of rock samples and their physical and mechanical characteristics, conceptual approaches to preventive and reinforcing measures necessary for the further safe survival of structures, as well as the comprehensive development and implementation of measures to prevent further damages (elimination of causes) and ensure the long-term existence of structures. Based on the analyses carried out, it is recommended to use a ready-made dry mixture mortar of the “Mapegrout'' brand produced by the Italian company “Mapei” to fill cracks if necessary. It is available in the market of the country and is successfully used in the reconstruction of tunnels and other underground structures. The issues of compatibility of reinforcing materials with sandstone rock are also considered on the basis of some averaged data of the main decisive physical and mechanical characteristics of the strength and deformation of sandstone.

REVIEW OF THE PHYSICAL AND MECHANICAL CHARACTERISTICS OF POLYURETHANE NANOCOMPOSITES

Polyurethane nanocomposites are promising materials in many industries, they have superior physical and mechanical properties compared to the original polyurethane. This paper presents an analysis of the physical and mechanical properties of polyurethane nano-composites with various types of fillers such as organoclays, carbon nanotubes, polyhedral oligomeric silse-squioxanes, graphene, graphene oxide, polytetrafluoroethylene, and metal nanoparticles. The concentration-dependent effects in changing the structure and properties of polyurethane composites under the influence of the added fillers were also considered. It is noted that the values of physical and mechanical properties are influenced by the uniform distribution of nanofiller particles in the composite and their chemical modification. It was found that with a uniform distribution of nanoparticles in the polymer matrix, the physicomechanical properties of the resulting composites increase.

INVESTIGATION OF THE PROCESS OF MODIFICATION OF PETROLEUM ROAD BITUMEN BY MALEIC ANHYDRIDE

The possibility of modification of oxidized petroleum bitumen 70/100 produced by JSC "Ukrtatnafta" (Kremenchuk, Ukraine) with maleic anhydride was studied. The influence of maleic anhydride amount, process duration, and temperature on the main physical and mechanical characteristics of modified bitumen was studied. The optimal amount of maleic anhydride introduction to bitumen was established. It is found that 2 wt. % maleic anhydride allows to increase the softening temperature of the modified bitumen (from 46 °C to 52 °C). Adhesion to crushed stone also increases (from 2.5 points to 4.5 points) and other indicators improve. Sufficient time to modify the bitumen with maleic anhydride was 30 minutes. The optimum modification temperature for obtaining the modified bitumen with maleic anhydride is 130 °C. Increasing the temperature of the modification has a negative effect on the final physical and mechanical properties of the binder.

COMPARATIVE EVALUATION OF BND 50/70 ROAD BITUMEN MODIFIED WITH SKEPT-60 AND SKN-26 ELASTOMERS

The article provides information on the physical and mechanical properties of polymer-bitumen compositions obtained by modifying road bitumen BND 50/70 with elastomers SKEPT-60 and SKN-26 and determination of the obtained polymer-bitumen composites. The properties of composite samples of various concentrations (2.5, 3.0, 5.0%, 6.5 and 7.0%) were determined: needle depth, softening, brittleness and flash point, stretching and adhesion. It was determined that the physical and mechanical characteristics of polymer-bitumen composite materials obtained at high concentrations (6.5, 7.0%) are improved