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Physical properties controlling water repellency in synthesized granular solids

Saulick, Y; Lourenço, SDN; Baudet, BA; Woche, SK; Bachmann, J; (2018) Physical properties controlling water repellency in synthesized granular solids. European Journal of Soil Science , 69 (4) pp. 698-709. 10.1111/ejss.12555. Green open access

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Abstract

The wettability of granular solids such as soil is known to depend primarily on two factors: their inherent chemistry and their physical properties, such as their particle size, particle shape and surface roughness. Nevertheless, the distinctive physical properties of such materials have not been fully explored to gauge their wettability. In this study, the difference in wettability between a flat solid (microscope slide) and three granular solids, namely glass beads (GB), Leighton Buzzard Sand (LBS) and crushed Glass (CG), which have different physical properties, were examined. The effect of chemistry was isolated by strongly hydrophobizing the above materials by treatment with dimethyldichlorosilane. Wettability measurements were made by measuring the water–solid contact angle (CA) by the sessile drop method after adhering one layer of uniformly oriented granular solids on to double‐sided adhesive tape initially attached to a microscope slide. Techniques for particle characterization included sieving for particle size, dynamic image analysis for particle shape and confocal laser microscopy to determine surface roughness. Results show that all CAs of the granular solids exceeded that of the hydrophobized microscope slide (103°). The crushed glass had the largest CA (125°). With all three granular solids, there was an increase in CAs as particle size decreased. In addition, as particles became more angular, CAs increased. The influence of shape on wettability became more predominant as particle size decreased. The surface roughness parameter, Ra, was investigated and shown to be sensitive to both the size and shape of the particles. A decrease in Ra from 95.4 to 34.1 μm increased CAs from 107 to 125°. A similar change in CA was shown to correspond to an increase in void fraction from 40.7 to 77.4%. Our results have practical implications for the optimum use of soil by enhancing or suppressing water repellency.

Type: Article
Title: Physical properties controlling water repellency in synthesized granular solids
Open access status: An open access version is available from UCL Discovery
DOI: 10.1111/ejss.12555
Publisher version: https://doi.org/10.1111/ejss.12555
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10043092
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