• Wiśniewski, Tomasz
• Furmański, Piotr
• Cieślikiewicz, Łukasz
• Kubiś, Michał
• Pietrak, Karol
• Seredyński, Mirosław
• Wasik, Michał
• Łapka, Piotr

Abstract

Few results of anisotropic thermal properties were presented in literature. Most of them were focused on thermal conductivity measurement through the sample thickness only or additionally in one in-plane direction parallel at the top sample surface. In this work thermal conductivities of several types of bricks were determined by means of indirect method. Hence thermal diffusivity, specific heat and density were measured for each type of sample. Thermal diffusivity of ceramic bricks has been measured using the flash technique within temperature range 30-60°C. Differential scanning calorimetry technique was applied for specific heat measurement at the same temperature range. Apparent densities were determined at room temperature. Measurements which were taken in three directions normal to the main planes of the brick revealed that thermal diffusivity in bricks is anisotropic. Investigations were repeated on several bricks coming from different local manufacturers. Differences of thermal conductivities determined for samples cut in various directions were up to 36%. The connection between principaldirections of thermal diffusivity tensor and microstructure of the material was also investigated using the scanning electron microscopy technique. The precisely evaluated thermal conductivity tensor might be of relevance in the modelling of heat and moisture transport phenomena in building materials.

Topics

• density
• impedance spectroscopy
• microstructure
• surface
• scanning electron microscopy
• anisotropic
• differential scanning calorimetry
• ceramic
• diffusivity
• thermal conductivity
• specific heat