Characterization of foamed concrete with different additives using multi-scale micro-computed tomography

In this study, microstructural characterization of various foamed concrete specimens was conducted using multi-scale X-ray microcomputed tomography (micro-CT). Foamed concrete specimens with cement only and fine sand or supplementary cementing materials (SCMs), such as fly ash and silica fumes, were prepared, which can improve the mechanical properties of the foamed concrete. Various water/binder ratios were also considered for each specimen, and pore and solid structures of the foamed specimens were analyzed. Micro-CT images with pixel sizes of 24.97μm (upper scale) and 0.65μm (lower scale) were combined to investigate the material characteristics. The effects of SCMs on the material characteristics was examined and correlated with the compressive strength of the specimens. The specimens for the upper-scale analysis were used to measure the physical properties of the materials, whereas the detailed microstructural characteristics of the specimens were investigated using a lower-scale micro-CT with relatively small samples. The results from the micro-CT at different scales demonstrated that the solid structures in the foamed concrete significantly affected the material strength based on the SCM type and water/binder ratio.