Article Periodicals » Materials Evaluation » Article
Infrared Thermography for Moisture Detection: A Laboratory Study and In-situ Test

Infrared thermography (IRT) was used to map moisture distribution and to identify areas with anomalous water content in modern and ancient building structures. This paper describes two different approaches that used IRT to map evaporative flux on wall surfaces, and to assess the potentials and limits of the technique. The first part of the paper describes a set of laboratory measurements to evaluate water diffusion inside the wall, as well as evaporation rate versus moisture content. Measurements of evaporative flux on laboratory samples provided an empirical relationship between evaporative flux and cooling under specific conditions inside mesopores and micropores allowing the typical trend of the evaporation rate to serve as a key for reading thermographic surveys to identify areas at greatest risk of surface degradation. Capillary rise (water rising from soil due to capillary of porous materials) was also evaluated under laboratory-controlled conditions. In addition, active and passive tests were applied in-situ to map different areas on the building surface according to water evaporation. The output was not the absolute moisture content, but rather a value ranked according to a scale on which the saturated condition represented the minimum negative value and zero represented the physical moisture content (dry). This map was coupled with the surface temperature as given by the natural evaporation when equilibrium conditions with the environment were reached, as in the passive approach. This was obtained by processing the experimental data using a robust algorithm that synthesized the surface temperature history during the test with enhanced evaporation. Finally, outputs of the processing algorithms were overlapped with the visible image and put in the same file.

Bison, P., G. Cadelano and E. Grinzato, “Thermographic Signal Reconstruction with Periodic Temperature Variation Applied to Moisture Classification,” 10th International Conference on Quantitative InfraRed Thermography, 27 – 30 July 2010, Quebec, Canada. Camuffo, D., Microclimate for Cultural Heritage, Elsevier Science, New York, 1998. Carslaw, H. S. and J. C. Jaeger, Conduction of Heat in Solids, Oxford University Press, New York, 1959. Grinzato, E., P. G. Bison, S. Marinetti and V. Vavilov, “Thermal/Infrared Non Destructive Evaluation of Moisture Content in Building: Theory and Experiment,” CNR Congress on Moisture, Part 1, Varenna, Italy, September 1994, pp. 345–356. Grinzato, E., G. Cadelano and P. Bison, “Moisture Map by IR Thermography,” Journal of Modern Optics, Vol. 57, No. 18, October 2010, pp. 1170–1778. Le Bray, Y. and M. Prat, “Three-dimensional Pore Network Simulation of Drying in Capillary Porous Media,” International Journal of Heat and Mass Transfer, Vol. 42, No. 22, November 1999, pp. 4207–4224. Ljungberg, S. A., “Infrared Techniques in Buildings and Structures. Operation and Maintenance,“ Infrared Methodology and Technology, Non-destructive Testing Monographs and Tracts, Vol. 7, CRC Press, 1994, pp. 211–252. Ludwig, N. and E. Rosina, “Restoration Mortars at IRT: Optical and Hygroscopic Properties of Surfaces,” Proceeding of 8th International Conference on Quantitative Infrared Thermography, 2006, Padova, Italy. Massari, G. and I. Massari, “Damp Buildings, Old and New,” El Estudio y la Conservación de la Cerámica Decorada en Arquitectura. Un Compendio de Colaboraciones, Conservation Studies 1, Rome, Italy, 1993. Rosina, E., N. Ludwig, S. Della Torre, S. D’Ascola , C. Sotgia and P. Cornale, “Thermal and Hygroscopic Characteristics of Restored Plasters with Different Surface Textures,” Materials Evaluation, Vol. 66, No. 12, 2008, pp. 1271–1278. Stockton, G. R. and A. Tache, “Advances in Applications for Aerial Infrared Thermography,” Thermosense XXVIII SPIE Proceedings, Vol. 6205, 18 April 2006. Tavukçuoglu, A. and E. Grinzato, QIRT Journal, Vol. 3, No. 2, 2006, pp. 231–245. Yioitis, A. G., I. N. Tsimpanogiannis, A. K. Stubos and Y. C. Yortsos, “Coupling External and Internal Mass Transfer during Drying of Porous Medium,” Water Resources Research, Vol. 43, 2007.
Usage Shares
Total Views
105 Page Views
Total Shares
0 Tweets
0 PDF Downloads
0 Facebook Shares
Total Usage