Periodic Asymptotic Homogenisation of a Clayey Sand–Kenaf Composite

Adobe is a building material with high thermal inertia, but it is characterised by low mechanical strength, whether in compression or flexure, due to poor water resistance. Modern stabilisation techniques make it possible to significantly increase the ductility of these adobe units. In the literature, the improvement of the mechanical properties of adobe bricks through the incorporation of fibres, such as kenaf, has been experimentally demonstrated. Sampling-based analysis is extremely time-consuming and costly. A numerical simulation approach enables the optimal selection of composite adobe components to achieve superior ductility. This article presents a numerical study on the periodic asymptotic homogenisation of a clayey sand/kenaf composite intended for the manufacture of load-bearing earth bricks. The results reveal two distinct regimes: a quasi-isotropic dilute regime for volume fractions (Vf)≤ 15%, and a concentrated regime with marked anisotropy for Vf＞15%. The shear modulus GXY is the most sensitive to the dosage and is quasi-proportional to the Young’s modulus of the fiber. The local von Mises stress reaches its absolute maximum at Vf=20%, marking the upper limit of the recommended practical range, which is |7-20%| (0.58-1.91 wt.%). Finally, our model’s predictions are validated by comparison with other methods and experimental results from the literature.