A multiphysics finite element framework for CO2-induced self-healing in bacterial concrete

This study presents a multiphysics finite element model to simulate CO₂-induced self-healing in bacterial concrete, offering a sustainable approach to crack repair and carbon sequestration. Unlike previous models, the proposed framework integrates coupled processes, including CO₂ diffusion, bacterial metabolism, moisture transport, and calcium carbonate precipitation, within a unified reaction–diffusion system. Implemented in FEniCS, the model uses refined meshing to resolve gradients near cracks and applies validated boundary conditions based on experimental studies. Simulations show that under optimal conditions (RH ≥ 80 %, CO₂ ≥ 20 %), over 90 % crack closure is achieved within six weeks for microcracks (≤0.5 mm), while larger cracks exhibit slower healing due to diffusion limitations. The model also demonstrates strong agreement with experimental data for carbonation depth and CaCO₃ formation, achieving a coefficient of determination (R²) of 0.996. These results confirm the potential of bacterial concrete for self-repair and carbon sequestration in humid, CO₂-rich environments. The model provides a robust tool for optimizing material design and curing conditions, paving the way for the development of low-maintenance, carbon-negative infrastructure.