Does ITZ influence moisture transport in concrete?

Published

July 24, 2022

Author(s)

Laura E. Dalton, Jacob LaManna, Scott Jones, Mohammad Pour-Ghaz

Abstract

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 capture unsaturated moisture flow in a concrete cylinder containing a single coarse aggregate. Neutrons and X-rays "see" materials differently due to differences in their interactions with nuclei and atomic electrons, respectively. Neutrons excel at detecting hydrogenous materials, such as 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 concrete materials. Combined results are achieved by collecting time-resolved neutron and X-ray tomography scans in one hour increments. The experiment is designed to better understand if moisture transport increases in the ITZ compared to the "bulk" cement paste during unsaturated flow. No indications of water preferentially migrating around the coarse aggregate during water ingress was captured at the resolutions of the dual neutron and X-ray scans. The ITZ does not appear to increase the mass transport of water during unsaturated flow and water moves uniformly through the entire cement paste matrix.

Citation

Transport in Porous Media

Pub Type

Journals

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Keywords

Concrete, Interfacial Transition Zone, Neutron Tomography, NeXT System, X-ray Computed Tomography

Citation

Dalton, L. , LaManna, J. , Jones, S. and Pour-Ghaz, M. (2022), Does ITZ influence moisture transport in concrete?, Transport in Porous Media, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933351 (Accessed April 30, 2025)