A multitechnique, quantitative characterization of the pore space of fired bricks made of five clayey raw materials used in European brick industry

The development and improvement of brick materials is still based on empirical knowledge and large testing series. To enable a physically based optimization in terms of thermal and mechanical properties of clay bricks, detailed knowledge of their microstructure is required. We here present comprehensive investigations on the pore space of bricks made of five different clayey raw materials used in European brick production. Application and combination of micro-computed tomography and scanning electron microscopy delivered precise pore size distributions based on the real pore diameter and unaffected by the pore throat. The former also enabled to resolve the 3D pore structure down to a pore diameter of approximately 5.5 micrometers and gave access to porosity distributions over the sample's thickness. Furthermore, the brick's true densities were determined applying the Archimedes' principle and verified by helium pycnometry measurements. The extensive database generated in this work and the linking of results from different methods allow for new insights and a better understanding of these often used brick materials.