IR Thermography (IRT) is applied to map moisture distribution, to localise areas with anomalous water content. In this paper two different approaches are presented using IR thermography as a tool for mapping evaporation flux on the surface, with the aim to find out the limits of the technique. The first part of the paper illustrates a set of laboratory measurements, which allows evaluating the evaporation rate versus the moisture content of different porous materials and the diffusion of water inside the wall. By data of evaporation flux measured in laboratory on samples it is possible to understand the behaviour of water inside the meso- and micro-pores to obtain an empirical relationship between evaporation flux and the cooling recorded by thermography, under particular conditions. From the typical trend of evaporation flux rate it is possible to infer a way to read thermographic passive surveys in order to single out the areas more at risk due to surface degradation. Secondarily, active and passive tests are applied in situ in order to map on the building surface different regions accordingly to the water evaporation. The output is not the absolute moisture evaluation, but a value ranked accordingly a scale, where the saturation condition represents the minimum negative value and the zero is the physiological moisture content (dry). This map is coupled to the IR picture of the surface whose temperature is given by the natural evaporation when equilibrium conditions with the environment are reached, as in the passive approach. This is obtained by processing the experimental data using a robust algorithm, that is able to synthesize the surface temperature history during the test with enhanced evaporation.
|Titolo:||Infrared thermography for moisture detection : a laboratory study and on the field test|
LUDWIG, NICOLA GHERARDO (Secondo)
|Parole Chiave:||Evaporation; Infrared imaging; Moisture; Thermography|
|Settore Scientifico Disciplinare:||Settore FIS/07 - Fisica Applicata(Beni Culturali, Ambientali, Biol.e Medicin)|
|Data di pubblicazione:||gen-2011|
|Appare nelle tipologie:||01 - Articolo su periodico|