Synchrotron-radiation computed tomography of the water drop penetration time test on hydrophobic soils

The water drop penetration time (WDPT) test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores. It is used to evaluate the hydrophobicity of materials. This study aims at investigating in more detail the soil-water interaction d...

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Main Authors: Clara M. Toffoli, Marius Milatz, Julian P. Moosmann, Thomas Jentschke, Felix Beckmann, Jürgen Grabe
Format: Article
Language:English
Published: Elsevier 2025-08-01
Series:Journal of Rock Mechanics and Geotechnical Engineering
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Online Access:http://www.sciencedirect.com/science/article/pii/S1674775525002665
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author Clara M. Toffoli
Marius Milatz
Julian P. Moosmann
Thomas Jentschke
Felix Beckmann
Jürgen Grabe
author_facet Clara M. Toffoli
Marius Milatz
Julian P. Moosmann
Thomas Jentschke
Felix Beckmann
Jürgen Grabe
author_sort Clara M. Toffoli
collection DOAJ
description The water drop penetration time (WDPT) test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores. It is used to evaluate the hydrophobicity of materials. This study aims at investigating in more detail the soil-water interaction during the test, exposing its mechanism. For that, a model soil named Hamburg Sand was coated with a hydrophobic fluoropolymer and then a WDPT test was performed while computed tomography (CT) images were taken. Tomography experiments were performed at the P07 high-energy materials science (HEMS) beamline, operated by Helmholtz–Zentrum Hereon, at the storage ring PETRA III at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg. Using synchrotron radiation, a tomogram can be obtained in about 10 min, way less time than regular laboratory X-ray sources usually owned by universities. The faster imaging enables the observation of the drop penetration during time and thus provides insight into the dynamics of the process. After that, digital discrete image correlation is performed to track the displacement of the grains throughout time. From the results one can observe that, as the drop is absorbed at the material's surface, the grains directly around the droplet base are dragged to the liquid-air interface around the drop, revealing grain kinematics during capillary interactions of the penetrating liquid and sand grains.
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spelling doaj-art-079cd47d7a144b0cbd0d19d185dcfc432025-08-20T04:00:28ZengElsevierJournal of Rock Mechanics and Geotechnical Engineering1674-77552025-08-011785111512110.1016/j.jrmge.2025.06.003Synchrotron-radiation computed tomography of the water drop penetration time test on hydrophobic soilsClara M. Toffoli0Marius Milatz1Julian P. Moosmann2Thomas Jentschke3Felix Beckmann4Jürgen Grabe5Institute of Geotechnics and Construction Management, Hamburg University of Technology, Hamburg, 21079, Germany; Corresponding author.Institute of Geomechanics und Geotechnics, Braunschweig University of Technology, Braunschweig, 38106, GermanyHelmholtz-Zentrum Hereon, Geesthacht, 21502, GermanyHelmholtz-Zentrum Hereon, Geesthacht, 21502, GermanyHelmholtz-Zentrum Hereon, Geesthacht, 21502, GermanyInstitute of Geotechnics and Construction Management, Hamburg University of Technology, Hamburg, 21079, GermanyThe water drop penetration time (WDPT) test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores. It is used to evaluate the hydrophobicity of materials. This study aims at investigating in more detail the soil-water interaction during the test, exposing its mechanism. For that, a model soil named Hamburg Sand was coated with a hydrophobic fluoropolymer and then a WDPT test was performed while computed tomography (CT) images were taken. Tomography experiments were performed at the P07 high-energy materials science (HEMS) beamline, operated by Helmholtz–Zentrum Hereon, at the storage ring PETRA III at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg. Using synchrotron radiation, a tomogram can be obtained in about 10 min, way less time than regular laboratory X-ray sources usually owned by universities. The faster imaging enables the observation of the drop penetration during time and thus provides insight into the dynamics of the process. After that, digital discrete image correlation is performed to track the displacement of the grains throughout time. From the results one can observe that, as the drop is absorbed at the material's surface, the grains directly around the droplet base are dragged to the liquid-air interface around the drop, revealing grain kinematics during capillary interactions of the penetrating liquid and sand grains.http://www.sciencedirect.com/science/article/pii/S1674775525002665Hydrophobic soilSynchrotron tomographyWater drop penetration time (WDPT) test
spellingShingle Clara M. Toffoli
Marius Milatz
Julian P. Moosmann
Thomas Jentschke
Felix Beckmann
Jürgen Grabe
Synchrotron-radiation computed tomography of the water drop penetration time test on hydrophobic soils
Journal of Rock Mechanics and Geotechnical Engineering
Hydrophobic soil
Synchrotron tomography
Water drop penetration time (WDPT) test
title Synchrotron-radiation computed tomography of the water drop penetration time test on hydrophobic soils
title_full Synchrotron-radiation computed tomography of the water drop penetration time test on hydrophobic soils
title_fullStr Synchrotron-radiation computed tomography of the water drop penetration time test on hydrophobic soils
title_full_unstemmed Synchrotron-radiation computed tomography of the water drop penetration time test on hydrophobic soils
title_short Synchrotron-radiation computed tomography of the water drop penetration time test on hydrophobic soils
title_sort synchrotron radiation computed tomography of the water drop penetration time test on hydrophobic soils
topic Hydrophobic soil
Synchrotron tomography
Water drop penetration time (WDPT) test
url http://www.sciencedirect.com/science/article/pii/S1674775525002665
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AT julianpmoosmann synchrotronradiationcomputedtomographyofthewaterdroppenetrationtimetestonhydrophobicsoils
AT thomasjentschke synchrotronradiationcomputedtomographyofthewaterdroppenetrationtimetestonhydrophobicsoils
AT felixbeckmann synchrotronradiationcomputedtomographyofthewaterdroppenetrationtimetestonhydrophobicsoils
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