Is the time-domain reflectometry (TDR) technique suitable for moisture content measurement in low-porosity building materials?

• Type: Article in International Scientific Journal
• Date: 2020-09-23

Authors

Ana Sofia Guimarães (Author) FEUP; Teresa Stingl Freitas (Author) FEUP; Vasco Peixoto de Freitas (Author) FEUP; Staf Roels (Author) Other; Andrea Cataldo (Author) Other

Journal

Title: Sustainability

Vol. 12 No. 19

Pages: 1-16

ISSN: 2071-1050

Publisher: MDPI

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 1 Citation

Other information

Authenticus ID: P-00S-VNM

DOI: 10.3390/su12197855

Abstract (EN): Measuring moisture content in building materials is essential both for professional practice and for research. However, this is a very complex task, especially when long-term minor destructive measurements are desired. The time-domain reflectometry (TDR) technique is commonly used for soil moisture measurements, but its application in construction materials is considered a relatively new method, particularly for low-porosity building materials. The major obstacles to its current use in construction materials are (1) the difficulty of ensuring good contact between the TDR probe and the material, and (2) the lack of appropriate conversion functions between the measured relative permittivity and the moisture content of building materials. This paper intends to contribute to overcoming these difficulties by explaining in detail all the required steps to monitor moisture content in real-scale limestone walls. For that, a device is presented to guarantee the correct installation of the TDR probes on the walls, and a calibration procedure through the gravimetric method is proposed to avoid the use of an unsuitable calibration function developed for soil moisture measurements. In addition, the importance of the individual probe calibration is discussed, as well as TDR advantages and disadvantages for construction materials. The results obtained so far reveal that the TDR technique is suitable to detect moisture content variations in limestone, which is a low-porosity building material. © 2020 by the authors.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16