Optimization of mechanical properties in anisotropic bio-based building materials by a multiscale homogenization model

Bio-based building material is derived mainly from waste agricultural by-products and has been intensively studied for its role in mitigating carbon emissions. This study aims to optimize its mechanical properties of bio-based building materials by a multiscale model based on micro-geometric characteristics. This model considered three common agricultural by-products: hemp, sunflower, and maize. Then the predicted results were compared with the experimental data. Moreover, the influence of the following parameters on the effective mechanical properties was investigated: volume fraction, modulus of binder and aggregate, shape, and orientation. In order to quantify the priority of each parameter in the optimization, a weight evaluation method was proposed. The analysis of the weight of these parameters shows that the modulus of the binder and the volume fraction of the plant aggregates have the greatest influence on improving the mechanical properties of the composites. When the aspect ratio of the plant particles is greater than 8, the change in their shape almost does not affect the results. Furthermore, this weight evaluation method was used in the case of bio-aggregates with high and low aspect ratios and volume fractions. The analysis shows that in the composite with a low aspect ratio, the optimization by orientation can take into account the performance in both vertical and horizontal directions. The higher the volume fraction, the better the optimization by shape and orientation. These findings provide a theoretical reference to improve the mechanical properties of bio-based building materials containing different agricultural by-products.