Abstract
Optimizing thermal and mechanical properties of clay block masonry requires detailed knowledge on the microstructure of fired clays. We here identify the macro- and microporosity stemming from the use of three different pore-forming agents (expanded polystyrene, sawdust, and paper sludge) in different concentrations. Micro-CT measurements provided access to volume, shape, and orientation of macropores, and in combination with X-ray attenuation averaging and statistical analysis, also to voxel-specific microporosities. Finally, the sum of micro- and macroporosity was compared to corresponding data gained from two statistically and physically independent methods (namely from chemical analysis in combination with weighing, and from mercury intrusion porosimetry). Satisfactory agreement of all these independently gained experimental data renders our new concept for identifying the pore spaces of fired clay as a very promising tool supporting the further optimization of clay blocks.
Highlights
Clay block masonry comfortably combines thermal and mechanical competences, making it one of the most sustainable and sought-after building materials, in particular when it comes to the construction of small storey houses
In order to check this new way of 3D quantification of the dual-scale ceramic porosities, independent experimental access to the porosities is provided by mercury intrusion porosimetry and weighing tests, as described in the ‘‘Mercury intrusion porosimetry and weighing tests’’ section
Histogram evaluations as described in the ‘‘Methods for macroporosity determination’’ section reveal macropores to be present in samples processed with expanded polystyrene (EPS) and sawdust, while samples processed with paper sludge are free of macropores, see Figs. 5, 6 and 7
Summary
Clay block masonry comfortably combines thermal and mechanical competences, making it one of the most sustainable and sought-after building materials, in particular when it comes to the construction of small storey houses. It is well accepted that porosities which are induced in a more or less designed way at different scales into the material, are the key governing factor for both its mechanical and thermal properties [1, 2]. In this context, pore-forming agents are used to increase porosity at scales ranging from micrometres to millimetres, in order to enhance the thermal insulation characteristics of the material. The corresponding results are presented in the ‘‘Results and discussion’’ section, and discussed thereafter
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