Analysis of the influence of porosity on mechanical properties of lightweight aggregate concrete based on differential box dimension method

Purpose The porosity of lightweight aggregate concrete (LWAC) plays a fundamental role in dictating its meso-scale damage evolution and macroscopic mechanical response. However, the quantitative relationship between porosity and the fractal dimension of crack morphology remains insufficiently elucidated. This study aims to quantitatively investigate this relationship. Design/methodology/approach A theoretical and computational framework is established by integrating the base force element method (BFEM), derived from the complementary energy principle, with the differential box-counting (DBC) method for fractal analysis. Porosity is treated as the sole variable in a meso-scale LWAC model. Uniaxial compression and tension simulations are conducted to obtain damage-field distributions at different stress stages, and the fractal dimensions of the evolving crack patterns are calculated using the DBC method. Findings The numerical results obtained from the proposed method are in good agreement with experimental data. The combined BFEM–fractal approach enables quantitative evaluation of the influence of lightweight aggregate porosity on the mechanical behavior and damage evolution of LWAC. Originality/value This study provides an effective analytical framework that integrates meso-scale numerical simulation with fractal analysis to quantitatively assess the influence of porosity on the mechanical properties of LWAC, offering new insight into the fractal characterization of crack morphology.