Micromechanical effects of silicon-enriched gradients on the compressive strength of Guadua angustifolia bamboo

This study investigates the microstructural, chemical, and mechanical characteristics of Guadua angustifolia Kunth bicolor (GAK-VB) bamboo, emphasizing the influence of silicon-enriched radial gradients on compressive performance. A combined experimental and finite element modeling approach was employed. Microstructural and compositional analyses were performed using environmental scanning electron microscopy (ESEM) coupled with energy-dispersive X-ray spectroscopy (EDS) on uncoated, unpolished specimens in a controlled environment to preserve the native morphology of the fibrous organic material. Compressive testing revealed that the outer 2 mm of the culm wall, which is enriched with up to 3.8 wt% silicon (Si), achieved a maximum strength of 97 megapascals (MPa), over twice that of the inner wall. EDS mapping confirmed a strong correlation between silicon content and localized mechanical performance. This suggests that silica deposition contributes to cell wall reinforcement, stiffness enhancement, and moisture-modulated durability. An orthotropic finite element method (FEM) shell model that incorporated measured compositional and mechanical gradients predicted buckling loads within 6% of the experimental values. This supports the adoption of gradient-based design parameters for structural applications. These findings advance the micromechanical understanding of bamboo and provide a framework for its optimized use in low-carbon, seismic-resilient construction systems.