Does ITZ Influence Moisture Transport in Concrete?

The contributions of the interfacial transition zone (ITZ) to mass transport in cement-based materials remain ambiguous and disputed. In this study, the neutron and X-ray tomography (NeXT) system is used to develop imaging techniques to capture unsaturated moisture flow and to determine the best technique for reconstructing the data. Neutrons and X-rays “see” materials differently due to differences in their interactions with nuclei and atomic electrons, respectively. Neutrons excel at detecting water, while X-rays resolve materials with high atomic mass such as dense solids. Therefore, neutron and X-ray tomography can generate complementary data to visualize the multi-faceted complexities of unsaturated moisture flow in cement-based materials. Combined results are achieved by collecting time-resolved neutron and X-ray tomography scans in one hour increments during water ingress in a concrete cylinder containing a single coarse granite aggregate. The experiment is designed to better understand if moisture transport increases in the ITZ region compared to the “bulk” cement paste during unsaturated flow. No indications of water preferentially migrating around the coarse aggregate in the ITZ region during water ingress was captured at the resolutions of the dual neutron and X-ray scans.

Duke Scholars

Author Laura Elizabeth Dalton Civil and Environmental Engineering