Bulletin of Prydniprovs'ka State Academy of Civil Engeneering and Architecture

9-15

Authors: V. N. Derevianko, A. Biegun, H. Hryshko, A. A. Maksimenko

In Ukraine there is an unreasonably high use of Portland cement, it is even used in the cases, when one can use the binding materials, manufactured at lower temperatures with less energy consumption. Manufacture of magnesium binding materials requires low–grade heat, as the base component MgO is burnt at temperatures lower than 1000° С. Energy required for production of the magnesium binding material is 30…40 % of the one required for Portland cement production, and the natural resources of magnesium minerals are abundant and make up at least 8 % of the Earth’s crust. Therefore low energy consumption allows for extensive use of magnesium binding materials in air–dry operating conditions, and studies on influence of magnesite burning modes on a structure and properties of a magnesia stone are up–to date. Adding of a fine–dispersed silica MgO–Н2O in the system will result in generation of magnesium silicate hydrates, which harden the magnesia stone, similarly to the behavior of calcium silicates at their hydration, while micro silica (silica fume) provides binding of free MgO to a complex oxychloride compound and increases the softening coefficient of hardened materials. The purpose of our studies was determining the influence of the burning temperature and the burning period on the properties and the mineralogical composition of the caustic magnesite. Moreover, we defined the methods for improving the properties of the caustic magnesite: waterproofing, reduced corrosivity, and thermal expansion coefficient. The article presents the results of chemical mechanical studies on the magnesium binding material, burnt at temperatures of 800, 970 and 1150° С. Burning of the magnesite at t = 800° С within 3 hours resulted in formation of a structure without oversintering (i.e. ballast) with crystals sized 34.4 nm, which is susceptible to cracking, with the bulk density of the powder ρон = 960 kg/m3, which implies a poorly crystalline structure and unsuitability for construction purposes. It was established, that binding properties are exhibited by the caustic magnesite produced at temperature of t = 970° С, the structure of which is formed by crystals sized from 38 to 43 nm. Increase of the burning temperature to 1150° С results in formation of a structure with oversintering of MgO grains from 7 % to 10,5 %. In this case, the sizes of the crystals were 47,9 to 48,1 nm. In the micrographs, hydrated at 25°С, there is displayed gel–like sodium hydroxide, which films unreacted MgO crystals. The scanning microscope study showed that the mass of the hydration product is much aggregated. These aggregates are clearly visible at low magnifications. The analysis of the electron microscopic studies on hydration of fine–dispersed periclase shows that the periclase crystals with no mechanical damages can reduce their sizes in aqueous environment within some period and not show evidence of surface hydration. This allows for creating a fast hardening solid structure of the magnesia stone due to simultaneous hydration of the burnt magnesite and interaction of magnesium hydroxide with fine ground quartz. Adding of a fine–dispersed silica MgO–Н2O in the system results in generation of magnesium silicate hydrates, which harden the magnesia stone.

19-23

Authors: K. K. Miroshnychenko

Problem definition. Over the last years the demand for fibre concrete has increased. Due to its properties it increasingly attracts the attention of scientists and manufacturers. However, the problem of high quality fibre concrete manufacture has not practically solved until present. This contains its wide use in building. Analysis of recent research: The analysis of present developments concerning this problem shows that over the last years there have been some investigations, however, they are not of system and fundamental character. Those research works do not consider essentially processes investigations that occur in a mixture being effected by mixer blades of various shapes. There are a few researches on fibre concrete production technology. Practically such a material manufacture is performed in common concrete mixers. The quality of compound is not satisfied. Purpose: Using geometric simulation to develop various variants of the blades of work members of mixers that ensure the efficient mixing of fibre concrete building compounds in the conditions of a construction site. Results: The use of the developed blades of complicated shape permits to get homogeneous fibre concrete compounds. Due to the high quality of mixing, the time of mixture making reduces. This helps to reduce repair equipment and electric power costs. Such introduced mobile production technology techniques permit to enhance essentially the application fields of fibre reinforced fine concretes. Conclusion. The article deals with the use of geometric simulation elements to develop the efficient mixer blade of complicated shape. The application of such a blade provides the efficient operation of fibre concrete compounds mixing.

32-42

Authors: А. Motornyi, N. Motornyi

The issue of the formation of denial of driven piles is discussed. It is assumed that the pile denial is the deformation of the soil layer located below the forming firm zone under the continuous instantaneous load transmitted through the soles of the firm cores from the blow of the hammer on the head of the pile. Propose to define the pile denial under the condition of energy balance — the formation energy of the hammer blow, and its expenditure on the submerged piles. It is given the ground for the formation of the optimal distances between the axes of the piles in the bunch and a pile field. It is specified the while crossing compacted zones overcrowded ground moves in the slit formed around the pile shaft, which eliminates the transmission of pressure on the side surface of the pile shaft and prevents movement of adjacent piles. It is given the ground for the formation of loosening soil in between pile uneven deformation loosening soil, the formation of holes and breaking the contact between the sole of the grillage and the foundation that violates their common work and does not allow to relieve piles under the load due to the inclusion of the pile grillage of the pile foundation in common work with the foundation.

47-54

Authors: V. Savyovsky, A. Bronevitskiy, A. Karzhinerova

In the modern, global and domestic practice is widespread process of reconstruction of industrial buildings and structures in objects civilian purposes. In the scientific and technical literature, this process is called — revitalization of industrial buildings. Revitalization (from Lat. Re — restoration, vita — life) — the revival, restoration and revitalization of urban space [1]. With the revitalization of the complex of works, which provides for the preservation of architectural buildings account of the creation of domestic content and interiors engineering and technological equipment, according to modern standards and requirements. In the case of reconstruction of architectural or historic sites are usually retain their foreign authenticity and expressiveness. The main task of revitalizing the reconstruction of industrial buildings and areas around them for socialization space, improve infrastructure, promote tourism, recreation, sports, environmental improvement. Revitalization of industrial buildings former gas tanks under civilian objects — has become a unique example of ecological reconstruction Megacities. "Old" buildings were not only an updated look, but also received a new attractive destination. The experience of construction work in the revitalization of industrial buildings, evidence of their multifaceted characteristics. Above, a significant amount of construction work was completed within three years. Considering the uschilnenist area and inside stysnennist works, the term indicates a high efficiency adopted organizational and technological solutions. Analysis of the experience points to the direction of rational options for construction works and contributes to the development of effective solutions revitalization of industrial buildings.