Microstructure and water absorption of ancient concrete from Pompeii: An integrated synchrotron microtomography and neutron radiography characterization

Abstract

There is renewed interest in using advanced techniques to characterize ancient Roman concrete. In the present work, samples were drilled from the "Hospitium" in Pompeii and were analyzed by synchrotron microtomography (μCT) and neutron radiography to study how the microstructure, including the presence of induced cracks, affects their water adsorption. The water distribution and absorptivity were quantified by neutron radiography. The 3D crack propagation, pore size distribution and orientation, tortuosity, and connectivity were analyzed from μCT results using advanced imaging methods. The concrete characterization also included classical methods (e.g., differential thermal-thermogravimetric, X-ray diffractometry, and scanning electron microscopy). Ductile fracture patterns were observed once cracks were introduced. When compared to Portland cement mortar/concrete, Pompeii samples had relatively high porosity, low connectivity, and similar coefficient of capillary penetration. In addition, the permeability was predicted from models based on percolation theory and the pore structure data to evaluate the fluid transport properties.

3D Nanotomography of calcium silicate hydrates by transmission electron microscopy

“…For the 3D nanostructure analysis based on TEM images, These two samples are synthetic samples because of the desire to have only one phase in the system so if the sample of Portland cement is analyzed, the image reconstruction and segmentation will be harder to do accurately because there are many phases in the system. In previous publications, 42,43 the authors proposed an automated image processing pipeline with machine learning‐based classifiers, which achieved accurate multiphase segmentation results for the 3D X‐ray micro‐tomography images of ancient Roman concrete samples. Similar methods can be used for the image segmentation of TEM tomography of real samples of Portland cement in the future study.…”

Neutron Imaging and Learning Algorithms: New Perspectives in Cultural Heritage Applications

“…Table 5 shows the DL applicable in the cultural heritage domain selecting the aim and the challenge addressed with the consequent improvement [ 65 , 66 ].…”

Sub- and supercritical hydrothermal route for the synthesis of xonotlite nanofibers for application to green concrete materials

“…10, which verified the accuracy of the phase segmentation. Further morphological measurements [49] of the volume and mean radius of segmented unhydrated particles, in this research, were conducted based on the segmented unhydrated phase. Table 2 gives the total volume and mean radius of unhydrated particles for reference and seeded pastes.…”