Imaging of unsaturated moisture flow inside cracked porous brick using electrical capacitance volume tomography

Concrete structures unavoidably suffer physical and chemical damage during service and hence easily crack. It is well-known that cracks in cement-based materials are preferential paths for the ingress of moisture and corrosive ions. Electrical capacitance volume tomography (ECVT) has previously been shown to be a powerful tool for imaging the spatial moisture distribution within cement-based materials. This paper investigated whether ECVT can be used for monitoring three-dimensional (3D) water penetration into porous materials containing different cracks. ECVT sensor with top electrodes and reconstruction algorithms were developed and evaluated respectively to improve the spatial resolution. The process of moisture ingress into bricks with different cracks was successfully visualized by ECVT, and the reconstructed results are in good agreement with the known properties of unsaturated water transport in porous materials. The ECVT reconstructions were also compared with moisture flow simulations, showing good agreement. Results suggest that ECVT is a viable tool for imaging 3D water penetration around cracks in porous materials, even for quantifying spatial water distribution.