EUPHORIA DAVIDII SUBILS (EUPHORBIACEAE) IN FLORA OF RAILWAY TRACKS OF DNIESTER BAY BAR

Aim. Anthropogenically transformed ecotopes act as a centre for existance of many adventive species. The distribution of North-American species Euphorbia davidii subsp. Poinsettia across various continents is often attributed to the export of grain. For some time scientists have been bringing up the issue about identification of plants E. davidii in new territories, because the species is morphologically similar to E. dentata agg. The species E. davidii is characterised by a high invasive potential, it is a neophyte. In Ukraine the species is represented by separate localities almost throughout the country. It is related to sectors of ports, railway tracks, and abandoned lands. Methods. In the year 2021, by means of route method, in sectors of railway tracks of the Dniester bay bar, between the railway stops Karolina-Buhas and Soniachna (total length is up to eight kilometers) seven localities of E. davidii were distinguished; the coordinates of the locations are listed in the publication. The examined ecotopes are characterised by a crushed stone substratum, with higher temperatures, and also by specific vibrational, insolational and hydrological modes. Results. Both inconsiderable in number of plants localities (32 exemplars) and zones, where the number of plants reaches over 2000 are represented. The extent of habitats ranges from 2 to 20 meters. The height of particular, the most developed individuals constituted 20 cm. As a rule, in the inter-rail space there is a considerably smaller number of plants, however, they are better developed, well-branched and have more inflorescences with fruits. Conclusions. A number of plants from the southern slopes of the railways is typically bigger, however, the plants on the southern slopes (in comparison with the northern ones) are worse developed, branch out less and, at the time of conducting the research were represented by a smaller number of generative individuals. In sandy sectors of the bay bar adjoining the railway tracks the plants E. davidii were almost not noticed. The individuals found in the above-mentioned sectors are characterised by stunted growth, a single stem, almost did not bloom, and did not produce seeds.

SELECTION OF A RATIONAL RECIPE OF LIGHTWEIGHT CONCRETE ON A MIXTURE OF CERAMSITE GRAVEL, NATURAL CRUSHED STONE AND GRANULAR SLAG

In conditions of dense urban development and a variety of engineering and geological conditions, the use of concretes with a combined aggregate of a rationally selected composition will solve the existing problem of reducing the mass of reinforced concrete structures of buildings and structures and maintaining the required strength and deformability. In this paper, studies have been carried out on the choice of a rational formulation of lightweight concrete based on expanded clay gravel, natural crushed stone and granulated blast furnace slag by varying the volume content of porous coarse aggregate and the volume content of fine aggregate in relation to the mixture. In total, 9 series of prototypes and 1 series of control samples are manufactured and tested. One series of samples includes three cubes with dimensions of 10x10x10 cm. All samples are tested in terms of density and compressive strength, the coefficient of constructive quality is determined. The results of the study shows that the introduction of expanded clay gravel into the composition of heavy concrete instead of part of the dense coarse aggregate and the replacement of the fine dense aggregate with granular blast furnace slag leads to an increase in the structural quality factor, that is, a decrease in the compressive strength of concrete is compensated for by an even more significant decrease in the density of the material, and means weight reduction. The increase in the coefficient of constructive quality of concrete based on expanded clay gravel, natural crushed stone and granulated blast-furnace slag in comparison with the control composition is 15.6 %.

Research of stress-deformed state of the rammed monolithic reinforced concrete cone-shaped piles with side and bottom forms from crushed stones

Relevance. In the construction of buildings and structures, driven piles with a square cross section are most widely used. To install them in the working position, the percussion method is used. However, in cramped conditions, shock loads can lead to dangerous conditions and destruction of structures of nearby buildings. In such a situation, it is necessary to use rammed piles, since technological solutions for their construction are not associated with shock effects on the soil. One such solution is the new rammed cone-shaped pile design, which is installed without excavation. The aim of the study is to analyze the influence of the geometric parameters of the pile on its bearing capacity under the action of external loads, in particular, the angle of its taper. Methods. The results of a numerical analysis of the stress-strain state of a pile operating in a soil massif were obtained by the finite element method. Results. In the computational study, a comparative analysis of the state of piles of different lengths and geometries under the action of external loads was carried out. The influence of the angle of inclination of the lateral surface of the pile on its bearing capacity is considered. Rationalization of the pile design was carried out taking into account the total costs of building materials. Variants of geometric and design solutions for piles with a length L from 1 to 10 m are proposed. In subsequent articles, it is proposed to consider the effect on the bearing capacity of the pile of the geometric parameters of the crushed stone shell and the lower crushed stone spherical expansion, as well as to carry out a comparative analysis of the numerical results with experimental data obtained in laboratory and field conditions.

Minimization of the impact of rubble production wastes on the environment by their involvement in the compositions of road'building materials

The impact of Taldan crushed stone plant and wastes formed in process of its activity on the environment is considered. About 2.9 million tons of siftings of rock grinding were accumulated in dump massifs with a total area of 600 hectares. Therefore, elimination of accumulated harm to the environment that has arisen over many years of operation of Taldan crushed stone plant is the actual task. One of the technological solutions of liquidation of objects of accumulated harm to the environment based on physicochemical impact on wastes is stabilization or artificial stone formation. Drawing of siftings of rock in soil concrete compositions (artificial stone materials) allows to solve complex of acute environmental problems due to their largetonnage direct use. The use of siftings of rock in road building will contribute to the rational and cost-effective use of natural mineral raw materials, since this process will not entail an increase in the costs of its extraction and processing. A set of modern methods (atomic-emission spectrometry with inductively coupled plasma, scanning electron microscopy, X-ray phase analysis, infrared spectroscopy) were used to study the chemical, phase composition and properties of siftings of rock to substantiate the possibility of its utilization in the composition of soil concrete. It is shown that the introduction of an 8 wt. % of mineral binder and polymer stabilizing additive Element (1, 5, 10 wt. %) allows to get soil concrete with a mark of strength М100.

Evaluation of geocell-reinforced backfill for airfield pavement repair

After an airfield has been attacked, temporary airfield pavement repairs should be accomplished quickly to restore flight operations. Often, the repairs are made with inadequate materials and insufficient manpower due to limited available resources. Legacy airfield damage repair (ADR) methods for repairing bomb damage consist of using bomb damage debris to fill the crater, followed by placement of crushed stone or rapid-setting flowable fill backfill with a foreign object debris (FOD) cover. While these backfill methods have provided successful results, they are heavily dependent on specific material and equipment resources that are not always readily available. Under emergency conditions, it is desirable to reduce the logistical burden while providing a suitable repair, especially in areas with weak subgrades. Geocells are cellular confinement systems of interconnected cells that can be used to reinforce geotechnical materials. The primary benefit of geocells is that lower quality backfill materials can be used instead of crushed stone to provide a temporary repair. This report summarizes a series of laboratory and field experiments performed to evaluate different geocell materials and geometries in combinations with a variety of soils to verify their effectiveness at supporting heavy aircraft loads. Results provide specific recommendations for using geocell technology for backfill reinforcement for emergency airfield repairs.

Investigation of the dispersed composition of dust of inert materials exposed to overload in the manufacture of building materials

At enterprises for the manufacture of building materials, when pouring bulk components, there is an intense emission of dust into the air of the working area of the room. The article presents the results of the dispersed analysis of dust when pouring cement, crushed stone, silicate bricks and chalk, and the integral functions of the distribution of dust particles by diameter are constructed. According to the criteria of Lyashchenko and Reynolds, the results of the sedimentation rate of dust particles were theoretically obtained. Measures are given to reduce the dust content of the air in the working area of the shop.

Substantiation of resource-saving technology when mining the deposits for the production of crushed-stone products

Purpose. Scientific substantiation of the expedient depth of mining the non-metallic deposits of rocky minerals on the basis of mathematical and statistical methods, which will ensure resource-saving and rational use of natural resources. Methods. To solve the purpose set, the following methods are used: graphical-analytical – when optimizing the maximum depth of mining the deposits of building materials, and the method of mathematical modeling – for determining the maximum depth of mining the non-metallic deposits with internal dumping. By means of statistical processing according to systematized types of deposits, the patterns of a change in the maximum depth of mining the basic deposits, depending on the main parameters of the quarry field, have been studied. Findings. A new methodology, which is distinguished by taking into account in-pit dumping, has been developed for calculating the maximum depth of granite quarries, which most of all influences the efficiency of mining operations and the value of economic indicators while ensuring the maximum economic effect with the achievement of a rational maximum depth of mining the deposit. A new, theoretically substantiated methodology has been created for determining the maximum depth of mining the mineral deposits for the production of crushed-stone products while providing the resource- and land-saving during the quarry operation. Originality. For the first time for these deposits, the dependence of their maximum mining depth on the main parameters of the quarry field and the place of internal dumping of overburden rocks has been determined. This has become a determining factor in the appropriate mining of deep non-metallic deposits of building materials with internal dumping, which provides a minimal land disturbance. Practical implications. The research results have been tested and implemented in working projects for mining the Liubymivske, Chaplynske, Pervomaiske, Mykytivske, Trykratske and Novoukrainske granite deposits; as a result of additional mining of mineral reserves, their additional increment in the volume from 1 to 48 million m3 is possible, which will ensure 5-40 years of sustainable operation of the mining enterprise.