## 4 IRT Different Case Studies from Diagnosis to Protection Interventions
### Moisture Detection  
Moisture is well known to be the most deteriorating factor of building materials [21]. IRT is a reliable technique for moisture detection [22], as it can distinguish between wet and dry by measurements of the thermal variations and can provide a clear indication of moisture movement and impact (i.e., moisture damage) in porous materials, based on emittance variations. The study and interpretation of an obtained thermal image could provide information on the moisture movement and impact to porous media.  
Below are shown two different cases, a study that tested salt damp movements in the laboratory and in situ in the medieval wall masonries in Rhodes, with the use of AVIO TVS-2000 Mk II LW, 8-12 \(\upmu\)m. The first one involves the use of IRT for monitoring a capillary rise of sodium sulphate ageing test, for brick-plasters systems (Figure 9) with various coatings [23].  
As shown in Figure 10, with the aid of IRT, it was possible to monitor the salt solution movements at the brick-plaster system. The thermal image corresponds to the profile of the brick-plaster for four different plasters. It can easily be seen which of the plasters favours the salt solution transportation to the front side of the system (central two samples) and for which the salt solution goes up to the brick  
Figure 8: Kaisariani Monasteri, area of investigation and thermal image.  
(the one on the left of the thermal image (point 1) and the other at the fight side (point 2)). The air temperature was \(\sim\)20 \({}^{\circ}\)C and relative humidity \(-\)50%.  
Moreover, in the following images we show the use of this technique on the masonry of the medieval complex of the island of Rhodes. This masonry is located at the moat and rising damp is one of the main causes of decay. A west-orientated masonry (Figures 11 and 12) comprised of consistently sized untreated stones was investigated. The back face of the masonry is constantly fed by salt solution due to the presence of the sea. The salt action is verified by the presence of efflorescence, while the extended recession of the surface is proved by the accumulation of disintegrated stone granules on the basis of the masonry.  
Figure 11: Photograph the investigated masonry in the Medieval Fortifications of Rhodes.  
Figure 10: IRT investigation of a salt solution capillary rise test in brick-plaster-coating systems.  
Figure 9: Brick-plaster-coating system.  
The obtained thermal image presents temperature variations on the surface of the investigated masonry, indicating the presence of humidity loads within the porous stones. The ambient conditions during the investigation were air temperature \(\sim\)22 \({}^{\circ}\)C and air relative humidity of 60%. The presence of moisture (lower temperatures on the infrared image) that arises as a result of the capillary movement of water has caused deterioration of the porous stone masonry. This is mainly because, during water movement inside the pores, there is also a movement of salts (from the presence of sea). Since such porous stones have high porosity values and large amounts of large pores that trigger capillary action, water movement inside their porous systems occurs [22; 24].