KFU scientists discover how the porosity of building ceramics affects its properties
Researchers from the Institute of Geology and Petroleum Technologies and Kazan State University of Architecture and Engineering have assessed the dependence of construction ceramics properties on their porosity.
“The properties of ceramic materials are determined by their mineral composition as well as the morphology of their porous structure,” explained Evgenia Nurieva, Associate Professor at the Department of Mineralogy and Lithology at IGPT. “The use of modern research methods such as computed tomography makes it possible to create environmentally friendly construction materials with specific technical characteristics from domestic raw materials and industrial waste. For instance, composite ceramics must have minimal thermal conductivity, absorb virtually no water, and exhibit high strength.”
During the experiment, the researchers produced ceramic samples from loam sourced at the Klyuchishchy deposit (Republic of Tatarstan), with the addition of two types of burnout additives of different origins – wood shavings and an oil sludge disposal product. Modifiers were also added to improve the forming properties of the clay mass and the physico-mechanical properties of the ceramics.
The method of X-ray computed tomography, applied to study the micro- and macrostructure of the composite materials, provided detailed information about the pore structure of the ceramic objects created by the researchers from clay raw materials.
“Using the KFU tomograph, we examined an initial ceramic sample without additives, as well as samples with additives. We concluded that there is no direct relationship between pore size and the properties of thermal conductivity, strength, and water absorption. The structure of the pore space plays a much greater role – specifically, the presence of interconnected (or open) pores,” said the Associate Professor. “Pore size has different effects on technical characteristics. We established that large pores reduce water absorption in the samples, while small pores, on the contrary, promote its increase. Using computed tomography, we were able to determine that large pores are closed, whereas zones of crack formation were found around small pores, through which capillary suction of water may occur.”
According to Nurieva, the highly porous ceramics – experimental samples of which were obtained during the study – possess considerable strength and low thermal conductivity, and can be used in the manufacture of bricks and blocks for the construction of energy-efficient walls. Based on such ceramics, it is possible to produce a “ceramic insulation material” that does not change its properties throughout the entire life cycle of a building or structure.
The results of the study, which was conducted using subsidy funds allocated as part of the state support for Kazan Federal University aimed at enhancing its competitiveness among leading global research and educational centers, are presented in a paper published in the journal Izvestiya Vuzov. Stroitelstvo [Notes of Universities. Construction].
