Imaging of foam concrete air bubbles with an alternative method of combined digital holographic microscopy

• Published in: Journal of materials science 2024-05, Vol.59 (20), p.8706-8720
• Main Authors: Celik Bayar, Caglar, Onur, Tugba Ozge, Ustabas Kaya, Gulhan, Kunduraci, Nazim
• Format: Article
• Language: English
• Subjects: Air bubbles; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Concrete; Crystallography and Scattering Methods; Foaming agents; Holography; Materials Science; Microscopy; Optical measuring instruments; Polymer Sciences; Quantum chemistry; Scanning electron microscopy; Shearing; Solid Mechanics; Thermal insulation
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-024-09726-x

Five different foam concretes were synthesized and examined. A new hybrid optical sensor, called combined digital holographic microscopy (CDHM), was proposed by combining microscopic fringe projection profilometry and lateral shearing digital holographic microscopy to detect the pore radii of produced foamed concretes. It was applied in addition to SEM and has not been applied to foam concretes before. Thanks to the proposed method, it was revealed that the measured CDHM radii contained a relative error of less than 6% compared to the SEM radii. The pore radii increased as the % of foaming agent used in the samples increased. Accordingly, the sample densities decreased and thermal insulation properties enhanced. Two-layer quantum chemical calculations performed at the ONIOM (M06-2X/6-31+G(d,p):UFF) theoretical level showed that thermodynamic stability of foam concretes increased as the % of foaming agent used, or more precisely, the pore radius, increased. The CDHM method provides results close to SEM and has superior features such as being more cost-effective, cleaner and faster. For this reason, it is thought that the proposed method will lead to future studies in terms of measuring pore radii as an alternative to SEM. Graphical Abstract The combined digital holographic microscopy (CDHM) method is proposed as an alternative to SEM with a relative error of less than 6% in determining the pore radius of foam concretes.