Transfer of innovative technologies

Destruction of reinforced concrete structures of sewage systems

2023-12-30T22:51:46+02:00

Composites materials are artificially created materials that consist of two or more components that differ in composition and are separated by a pronounced boundary. The development of modern composite materials is associated with the discovery of high-strength whiskers, with the study and use of aluminides and high-strength alloys. At present, various composite materials have been developed and used: fibrous; reinforced with whiskers and continuous crystals and fibres of refractory compounds and elements; dispersion-hardened materials; layered materials; alloys with directional crystallization of eutectic structures; alloys with intermetallic hardening. There are many technologies for producing composites: imbibition of reinforcing fibres with matrix (base) material; cold pressing of components followed by sintering; sediment of the matrix by plasma spraying on the hardener, followed by compression; batch diffusion welding of multilayer tapes of components; joint rolling of reinforcing elements with a matrix, and etc. The use of composites makes it possible to reduce the weight of aircraft, cars, ships, increase the efficiency of engines, and create new constructions with high performance and reliability. The development of composites with high impact resistance is an important direction in the industry. The strength characteristics of a layered composite material are decisive under shear loads, loading of the composite in directions other than the orientation of the layers, and cyclic loading. In this paper, we study the non-stationary interaction of an absolutely rigid body on a two-layer reinforced composite material. The action of the striker is replaced by a non-stationary vertical even distributed load, which changes according to a linear function, in the area of initial contact, which is assumed to be unchanged over time.

In contrast to the previous articles (Parts I and II), in this papers there is an investigation of the strain-stress state, the fields of the Odquist parameter and normal stresses depending on the material of the first (upper) layer.

Fire and biological protection of paper and corrugated board with an impregnating composition

2023-12-30T23:05:32+02:00

The issue of fire protection of cellulosic materials has been studied in the works of domestic and foreign scientists. However, there are still a number of unresolved problems in this area: modern means are not effective enough, the treated products are unaesthetic, do not meet performance indicators, and do not resist biodegradation. It has been established that volatile mixtures of pyrolysis products differ significantly in the content of combustible gases. Thus, for the treated samples, the amount of methane decreases by 30 times, hydrogen – by 25...30 times, carbon monoxide – by 35...40 times, and the amount of non-combustible gases increases: carbon dioxide - by 1.2...2 times, nitrogen – by 1.4...5 times. Studies on determining the smoke-forming capacity of untreated and treated paper samples showed an 8-fold decrease in the smoke-forming coefficient for treated paper samples and their transition from the group of materials with high smoke-forming capacity (untreated samples) to the group of materials with moderate smoke-forming capacity. Tests were conducted to determine the flammability of corrugated cardboard samples used for packaging various materials, including combustibles: untreated samples are classified as flammable materials, and treated samples are classified as flammable materials with a 42.38 kg/m³ absorption of the impregnating composition in terms of anhydrous substance.

Studies have been conducted on the fire and biological protection of paper and products made of it with an impregnating composition that can effectively protect against fire and biological degradation without compromising the aesthetic and operational characteristics of these materials, taking into account modern environmental requirements. To determine the flame retardant effect of the impregnating composition, thermal destruction of untreated and treated paper samples was performed. In the course of the study, volatile products of thermal degradation were collected and their gas chromatographic analysis was carried out.

Modified high strength lightweight-aggregate concrete based on expanded clay: composition, structure, properties

2023-12-30T23:15:41+02:00

The study is devoted to the development of increased strength lightweight concrete based on Portland cement modified with a complex organo-siliceous additive containing a polycarboxylate superplasticizer and an active fine-ground siliceous component. The effect of this complex additive on the physical and chemical characteristics of the hydration and structure formation processes was investigated and it was shown that the high kinetics of the strength gain is provided by directional formation of low-basic calcium hydrosilicates, hydrogranates and plazolite, which are crystallo chemically similar to each other, and provide a dense and strength cement stone matrix.

Modification by a complex additive makes possible to obtain concrete mixes with S4 consistency while a portland cement consumption per 1m³ of not more than 330 kg, with a compressive strength of 55 MPa, watertightness up to W8, frost resistance up to F400, corrosion resistance coefficients K_c in the magnesium sulfate, sodium and ammonium solutions by 10 to 24%. The introduction of a complex additive also helps to reduce the relative shrinkage by 16 ... 19% compared to the control composition, which has a positive effect on the durability of the resulting concrete.

Effectiveness of the using powder coating for protection of metal construction

2023-12-30T23:35:57+02:00

Сurrent state of the Ukrainian economy causes to resolve a range of questions related to the improvement of production and increase in the ecological safety of products, including paint-and-varnishes materials, in combination with ensuring high operational properties of coatings based on them.

This questions can be solved by scaling up production using eco-friendly powder coating. The increase in popularity of powder coatings can be explained by their environmental adequacy and attractiveness from the perspective of the environmental protection as well as high effectiveness related to the possibility of obtaining high quality protective and decorative coatings with the high corrosion and chemical resistance as well as controllable physical and mechanical and dielectric characteristics during the one-layer application.

The analysis of research results shows that the effectiveness of use of metakaolin and talc as fillers in the powder coating increases in proportion to their content in the system. The optimal area of the powder coating with metakaolin and talc is limited to the additive in the range of 20 to 30 % and polyester resin in the range of 55 to 65 %. Using the mentioned range of fillers in the powder coating contributes to the decrease in the peeling width and metal corrosion width and places the coating into atmospheric corrosivity categories С3 and С4 according to ІSO 12944-2:2017 having a high (Н) lifespan from 15 to 25 years in accordance with DSTU ISO 12944-1

In this case, one of the most common methods of influence on properties of paint-and-varnishes coatings is to create polymer composites by combining polyester raw materials with inorganic fillers.

Use of waste glass in concrete: A review

2023-12-30T23:42:44+02:00

Concrete is widely used construction material in the present industry. The concrete consists of cement, fine aggregates and coarse aggregates. Concrete is strong in compression and weak in tension. Also, the cement manufacturing industry on an average emits 7% of greenhouse gases to earth’s atmosphere which leads to global warming. In order to address these environmental affects extensive research is ongoing into the use of cement replacements, using many waste materials (like waste glass, plastics, fly ash, etc.) and industry’s byproducts. Waste glass is a non- biodegradable material and disposal of waste glass into the land results in the soil pollution. So, to avoid these disposable problems waste glass may be used as partial replacements of coarse and fine aggregates. It’s possible to add glass in the concrete by replacing either of the ingredients partially in a number of forms. Glass may be added in crushed form or in powder form along with the addition of admixtures/plasticizers or without addition of any of the alternate materials in the nominal concrete. Accordingly, a study about various aspects of usage of glass has been made in this paper to include it in concrete as an ingredient so that the best possible usage of glass form may be finalized and same may be used in the concrete with a partial replacement.

System "dispersed polyvinyl acetate-calcium silicate" in furnishing materials

2023-12-30T23:51:47+02:00

This article focuses on the processes of interaction between calcium silicate hydrates and dispersed polyvinyl acetate in tight films with the aim of developing compounds meant for restoration and finishing works. The basis of this development relies on the concept concerning the determining role of the crystal-chemical factor of the silicate phase in the formation of organic-mineral compounds of increased durability. The characteristics of dispersed calcium silicate hydrates are portrayed. The preparation conditions, accounting for the synthesis of the product of submicrocrystalline structure, conforming with the stoichiometry CaO:SiO₂=0.8-2.0 have been determined. The interaction has been studied for compounds achieved by mixing ingredients in a rapid whirling mixer, and subjected to hardening at T=20+2 °C. With the aid of XRD, DTA and Infra-Red Spectrometry methods the formation process of the sophisticated polymer silicate phase in the material was observed for a period of 90 days. The properties of the film were investigated and its high resistance against the influence of external factors was established. On this basis a conclusion concerning the quite high effectiveness of substituting portland cement with dispersed calcium silicate hydrate in polymer cement compounds has been made White colour and other various special properties determine the suitability for repair and finishing works on facades of buildings.

Comparison of the influence of the type of acidic environment on the properties of acid-resistant alkali-activated cements

2023-12-31T00:04:00+02:00

The article is devoted to the study of acid resistance of materials developed on the basis of hybrid alkali-activated cements and includes the results obtained during previous studies focused in this direction. This directly concerns the composite compositions of the received cements.
The relevance of the research is ensured by the need of the world market of building materials for modern, effective materials that will retain high acid resistance indicators along with increased physical, mechanical and technological characteristics. After all, as is known, traditional acid-resistant cements based on liquid potassium and sodium glass, although they provide appropriate values of resistance to the influence of an acidic environment, are extremely sensitive to the influence of water, which greatly reduces their service life. And materials based on Portland cement are generally not characterized by acid resistance due to the high content of portlandite (Ca(OH)2), highly basic calcium hydrosilicates and ettringite in the structure of hardened cement stone. That is why alkali-activated systems were chosen as the basis, the experience of working with them confirms the effectiveness of their use in the development of this research area.
In the course of this study, a comparative characterization of the influence of the type of aggressive environment on the processes of structure formation of cement stone and the formation of acid-resistant phases is conducted. 5% solutions of hydrochloric (HCl) and nitric (HNO3) acids were used for the study. The obtained results not only confirm the possibility of using such cements in the conditions of an aggressive environment with a low pH, but also reflect the degree and influence of this type of environment on the material made according to the presented compositions. Thus, the compressive strength of the samples made according to these tested compositions after 90 days of exposure in hydrochloric and nitric acid solutions ranges from 43.1 MPa to 45.7 MPa and from 47.1 MPa to 49.7 MPa, respectively.

Generative Ai: potential and pitfalls

2023-12-31T00:39:27+02:00

The explosive popularity of ChatGPT around the world gave us the first real tipping point in public acceptance of AI. Finally, everyone, everywhere can see the breakthrough potential of this technology for themselves. Large language models (LLM) and the fundamental models underlying these advances in generative artificial intelligence (GenAI) represent a significant turning point. Not only have they cracked the code of language complexity, allowing machines to learn context, infer intent, and be independent creative individuals, but they can be quickly configured to perform a wide variety of different tasks. This technology should fundamentally change everything — from science, business, health care to, in fact, society itself. The positive impact on human creativity and productivity will be enormous. Companies will use these models to rethink the way work is done. Every role in every enterprise has the potential to be reimagined, as AI people working as co-pilots become the norm, greatly expanding their capabilities. Generative AI will affect tasks, not professions. Some of these tasks will be automated, some will be transformed by artificial intelligence, and some will remain unchanged. It can also be expected that humans will face a large number of new challenges, such as ensuring the accurate and responsible use of GenAI systems. That's why organizations that invest in training people to work with generative AI will have a significant advantage.

Corrosion properties of aluminum-based alloys used in building constructions for different purposes

2023-12-31T00:17:09+02:00

The corrosion resistance of an aluminium alloy АD 31, that is used in building constructions, is investigated. The connection between change of samples weight and time of corrosion tests is established. It is shown, that the corrosion is accompanied by simultaneous course of two processes: by oxide film formation and dissolution of more active metal. The temperature dependences have shown, that with the temperature increase higher 80°С the corrosion resistance is reduced. The accounts of weight and deep parameters of corrosion are made.

Modelling of soil destruction process by bulldozer using a spatially oriented working unit

2023-12-31T00:31:20+02:00

The article uses approaches to creating a model for calculating soil cutting forces by spatially oriented working units of construction machines used on construction sites. The use of such a model is due to the need for continuous improvement of existing equipment and the creation of new ones, taking into account the existing needs. Today, there is a need for efficient performance of construction works related to the operation of construction equipment with dumping equipment. This, in turn, poses the task of determining the performance of mechanised earthworks in various working environments, one of the most common in Ukraine being marl clay, loam and argillaceous clay.

The main method of mechanical soil development is cutting. The main geometric conditions are the position of the cutting wedge edge relative to the cutting direction and the surface of the massif, the outline of the cutting edge, the outline and number of working surfaces of the cutting wedge, the number of so-called side cut surfaces and the so-called blocked cut surfaces. The peculiarity of the digging process is that its power and energy indicators depend on the kinematic conditions and geometric parameters – thickness, width and area of the cut, as well as on the angles of orientation of the working unit in space.

The computational model was created in accordance with the working hypothesis, where the movement of spatially oriented knives moves perpendicular to the blade equipment, at different ratios of the blade movement speed and knife movement, which creates spatial interaction with the working environment, and the deviation of the application of the full cutting force by an angle α.

In accordance with the working hypothesis, we obtained five plans for the movement of the spatially oriented blade of the blade. Depending on the plan of movement of the spatially oriented knife, its geometric interaction with the working environment changes and the cutting force changes accordingly.

The need to create more productive and efficient earthmoving equipment requires the use of modern design solutions. In the course of the study, a model for calculating the cutting of soils by spatially oriented earthmoving tools in the form of a dihedral knife of dump equipment was created. A comparison of soil cutting forces at different depths during the operation of a spatially oriented working body is also proposed. The results are summarised in the form of tabular data and graphs.