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AbstractDue to the environmental protection requirement, fired clay bricks are not only satisfied with mechanical strength but also rising energy utilisation. Based on the analysis of microstructure, it can be found that fired clay bricks are porous composite materials. The research objective of this article is to study the effect of micropores in order to provide a reference to achieve a compromise between mechanical and thermal properties. Firstly, a simplified representative volume element containing solid matrix and pores is presented at a microscale. Next, the homogenisation technology is introduced to build a micro–macro relationship. In this paper, Ponte Castañeda–Willis scheme considering the spatial distribution of micropores is used to predict the effective elastic properties and effective thermal conductivity of fired clay bricks. The results are compared with those by Mori–Tanaka scheme. Walpole’s notation is introduced to describe the transversely isotropic elastic tensors. Then, parameter calibration and experimental validation are implemented. Lastly, several conclusions and perspectives are given. Based on our results, porosity, the aspect ratio and the spatial distribution of micropores can affect the elastic and thermal properties, so we can control the macroscopic properties by changing the three factors.

Cement-based materials suffer from low tensile strength and poor strain capacity. They are brittle and highly sensitive to cracking, notably to cracking due to length changes whatever the original cause of the length change. This study shows that a partial replacement (by volume) of natural aggregates by rubber aggregates obtained by grinding of used tires is a suitable solution to improve the strain capacity before the macro-crack formation, conferring to the rubberised concrete a reduced propensity for shrinkage cracking. Moreover, the modulus of elasticity is advantageously reduced and it can be predicted using mix laws such as Hashin-Shrikman low bound considering rubberised concrete as a two-phase composite. Despite its low strength, the elastic quality index (EQI) of rubberised concrete remains in the range of values used for the design of pavements on soil. Besides this potential in terms of pavement application, it is also an interesting way to utilise industrial by-product and consequently a contribution to keep environment clean.