FORECAST EVALUATION OF HEAT PROTECTION AND MECHANICAL PROPERTIES OF INSULATING CONSTRUCTION CERAMIC MATERIALS

An integrated approach to determine the rational design of wall ceramic products based on modeling their behavior under operating conditions is proposed. This approach was used in the development of technology for heat–efficient insulating construction ceramic materials for energy–saving construction. For two models of porous–hollow ceramic products with a porous frame (40 % of voids) and a dense frame (60 % of voids), a predictive assessment of their heat–shielding and mechanical properties was carried out. Calculations of the equivalent coefficient of thermal conductivity of models based on Fourier’s law established that with a decrease in the voidness of products with a porous wall, the coefficient of their thermal conductivity decreases by 12 %, which improves the heat–shielding properties. Based on the results of computer simulation of the behavior of models under the influence of static power loads, it was determined that porosity of the ceramic framework of products leads to degradation of mechanical strength almost proportionally to a decrease in voidness. The stress–strain state of 3D models of ceramic structures with different pore geometry (spherical, globular, ellipsoidal) is analyzed and it is shown that stresses are concentrated in the contact zones of a ceramic matrix with pores. It is shown that the most durable is the structural model with spherical pores. The expediency of organizing such a structure, the need to strengthen the ceramic matrix of materials and zones surrounding the pores, as the most vulnerable structural sites, is shown. The results of predictive calculations have been experimentally confirmed in the development of technology for structural and heat–insulating composite–type ceramic materials based on low–melting loam and ash microspheres, which provide a given structural picture of the ceramic material.

Orthodox Devotionalia in Vilnius. Location, Dating and Significance of Old Russian Encolpions in Cultural Layers of the City

Древнерусские энколпионы являются довольно редкими находками, особенно в городских культурных слоях. В археологическом материале Литвы любая находка древнеруссского энколпиона - исключительная редкость, заслуживающая особого внимания. При археологических раскопках Вильнюса было обнаружено несколько энколпионов и их частей - в основном в восточной части нынешнего старого города и на территории Вильнюсского Нижнего замка. При анализе местонахождений энколпионов было сделано предположение, что изготовлением строительной керамики в Вильнюсе с XVI в. могли заниматься православные мастера. Еще одна версия о местонахождении древнерусских энколпионов появилась при наложении на план Вильнюса бывших дорог и торговых путей. Оказалось, что все энколпионы были найдены у бывших дорог, некоторые из них существуют и сейчас. 4 энколпиона были найдены у дорог восточного направления - на Полоцк, Витебск. Удалось установить, что возможны два промежутка времени попадания энколпионов в Вильнюс - или они появились на раннем этапе в XIII-XIV вв., в период расцвета Русского конца, или уже позднее, в XVI в., в период расцвета самого города. Old Russian encolpions are quite rare finds, especially in city cultural layers. In archaeological material of Lithuania any find of an Old Russian encolpion presents the exclusive rarity which has deserved exclusive attention. During the archaeological excavations of Vilnius several encolpions and their fragments - mainly in the Eastern part of the present old city and on the territory of the Vilnius Nizhny Castle were found. The analysis of encolpion location has guided us to the assumption that since the 16 century orthodox masters could be engaged in construction ceramic production in Vilnius. One more version about locations of Old Russian encolpions, has appeared when we «imposed» the former roads and trade ways on the plan of Vilnius. It has turned out that all encolpions were found at the former roads, some of them existing now. 4 encolpions were found at the roads of eastern directions - to Polotsk and Vitebsk. The author succeeded in establishing two most probable periods when the encolpions could have appeared in Vilnius: they either appeared there at an early stage in 13 - 14 centuries, during the Russian End florishing, or later, in the16 century during florishing of the city itself.

Use of Construction Waste to the Mass Manufacture of Clay Products

The objective of this study was to use the waste in the construction ceramic, because it does not degrade in nature due to its chemical composition and a contribution to the reduction of this waste in landfills and visual pollution. Thus, a sample of this material was selected so that their characteristics regarding chemical composition, X-ray diffraction, differential thermal analysis and thermogravimetric analysis could be studied. Mixtures were prepared containing 0%, 5%, 10%, 15% and 20% by weight of waste, and sintered at a temperature of 850 ° C. After water absorption, linear shrinkage and mechanical strength tests were performed. The physical-mechanical properties were determined according to the% of waste added. The results revealed a series of phase transformations during sintering. Moreover, the sintered bodies containing residual construction are likely use in red ceramic, contributing to waste minimization and self-sustained development.