Pore network characterisation of real building materials

The transfers of heat and moisture in porous building materials play a critical role in the health and comfort of building occupants and the durability and sustainability of built structures.  Just one example is corrosion of concrete reinforcement bars due to chloride invasion with the pore water.  Any analysis and design of built structures thus requires knowledge of the hygrothermal properties of the building materials involved, like the thermal conductivity, thewater absorption coefficient, …  Such properties strongly depend on the pore structure of the material and much research at the Building Physics section is oriented towards that relation between the material’s properties and the material’s microstructure.  Two of our past PhD students have been working on pore-scale modelling of these heat and moisture transfer properties of porous materials, where prediction of the macroscopic property of the material based on the microscopic storage and transport processes in the pores was accomplished. 

Their work can only be applied to real building materials if we can properly image and characterise the pore structures of these building materials, and this project is thus very important in that larger framework.  Most building materials have pores ranging from nano- to millimeter, and all these scales are important for the hygrothermal behaviour of the materials.  Therefore, the complete imaging and reconstruction of pore structures of building materials, from nano- to millimeter, is the target of this PhD project.  To that aim, firstly a multiscale imaging of the material’s pore structure is to be obtained,via 2D (e.g. broad-ion beam scanning electron microscopy, focused ion-beam serial cross-sectioning) and 3D (e.g. computed x-ray tomography) imaging techniques.  Secondly, these multiscale and multidimensional images are to be integrated to reconstruct the pore structure of the material in its full completeness and complexity, for which several approaches are to be compared in relation to efficiency and accuracy.