Distributed water ingress and water potential measurements using fibre optics

Michie, W.C., Culshaw, B., McLean, A., Konstantaki, M. and Hadjiloucas, S. ORCID: https://orcid.org/0000-0003-2380-6114 (1997) Distributed water ingress and water potential measurements using fibre optics. Cement and Concrete Composites, 19 (1). pp. 35-44. ISSN 0958-9465 doi: 10.1016/S0958-9465(96)00039-X

Abstract/Summary

We report on a distributed moisture detection scheme which uses a cable design based on waterswellable hydrogel polymers. The cable modulates the loss characteristic of light guided within a multi-mode optical fibre in response to relative water potentials in the surrounding environment. Interrogation of the cable using conventional optical time-domain reflectometry (OTDR) instruments allows water ingress points to be identified and located with a spatial resolution of 50 cm. The system has been tested in a simulated tendon duct grouting experiment as a means of mapping the extent of fill along the duct during the grouting process. Voided regions were detected and identified to within 50 cm. A series of salt solutions has been used to determine the sensor behaviour over a range of water potentials. These experiments predict that measurements of soil moisture content can be made over the range 0 to – 1500 kPa. Preliminary data on soil measurements have shown that the sensor can detect water pressure changes with a resolution of 45 kPa. Applications for the sensor include quality assurance of grouting procedures, verification of waterproofing barriers and soil moisture content determination (for load-bearing calculations).

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/18974
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Biological Sciences > Department of Bio-Engineering Interdisciplinary centres and themes > Soil Research Centre
Uncontrolled Keywords	Optical fibre sensors; distributed sensing; hydrogels
Publisher	Elsevier
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