Three-dimensional geometry, pore parameter, and fractal characteristic analyses of medium-density fiberboard by X-ray tomography, coupling with scanning electron microscopy and mercury intrusion porosimetry

Pore structure parameters are significant for investigating the diffusion properties of volatile organic compounds from building materials. Traditional characterization methods could provide ether surface morphology or some pore parameters of the material, which could not comprehensively reflect the overall information. X-ray tomography, as an advanced nondestructive method, can not only characterize the three-dimensional structure characteristics but also comprehensively measure pore parameters of materials. This study applied X-ray tomography to systematically analyze the geometry and volatile organic compound emission paths of medium-density fiberboard. The three-dimensional structures of pores and materials were reconstructed respectively. The isolated pores and connective pores were extracted to indicate the pore connectivity, and skeletonization was simultaneously applied, allowing visualization of the volatile organic compound diffusion paths. The porosity was 54.67%, and 99.91% of the pores were connective pores. The tortuosity was 2.07, and the fractal dimension was 2.605, indicating the heterogeneity and self-similarity of pore structures. Scanning electron microscopy was used to characterize the two-dimensional morphology of the material, and mercury intrusion porosimetry was applied to analyze the pore parameters. The results were consistent with that of X-ray tomography, and their coupling with X-ray tomography could comprehensively characterize the structures and parameters of indoor building materials, which could contribute significantly to future research on volatile organic compound emission mechanisms and building physics.