Characterizing physical properties of lightweight aggregate made from waste coal ash using X-ray computed tomography

X-ray computed tomography (XCT) is a powerful nondestructive technique that can provide valuable information about the physical properties of materials. This thesis uses XCT to evaluate the physical properties of a new type of lightweight aggregate (LWA) from low- and high-calcium waste coal combustion ashes (CCAs), i.e., spherical porous reactive lightweight aggregate (SPoRA). Raw data acquisition audition and image processing methodology are introduced in this study to evaluate the physical properties of SPoRA. The pore-solid structure of SPoRA is qualitatively analyzed using the 2D reconstructed XCT images. The physical properties of the LWAs including total porosity, closed porosity, pore volume and sphericity are characterized. Analysis of 2D images indicates that the SPoRA possesses a core-shell structure, where large pores are accumulated in the shell while core embeds small interconnected pores. Moreover, it is observed that increasing the fluxing agent (i.e., NaOH) concentration for preparation of SPoRA leads to a reduction of the core size and an increase in the shell thickness.