Ir thermography to compare the evaporation fluxes in brick masonry

The decay in masonry due to moisture has been generally treated as a measure of the water content. This parameter acts on the thermo-mechanical properties of the material but, with regards to the superficial decay, it is more relevant to evaluate the water passage at the interface masonry/environment and the salt transport connected with it. Salts, deposited by water evaporation, crystallize in the pores of the construction material and their increase in size may cause rupture of the material. The evaporation rate of the water passage from the material to the environment can be satisfactorily monitored by IR thermography as the material superficial temperature during evaporation decreases. This temperature change is expected to range up to a few degrees according to the speed of the phenomenon, which is function of the material characteristics and the environment conditions such as availability of moisture, air temperature and relative humidity, wind, etc. In connection with a wider experimental work aimed at investigating decay in large brick masonry specimens with simulated water and salt capillary transport in natural environment, a few laboratory evaporation experiments have been carried out in controlled conditions on slices of brick units, previously saturated in fresh water, repeatedly weighted and monitored by IR. During the different experiments, intended to simulate evaporation in different climatic seasons, alternatively were varied the air temperature and humidity, the ventilation. The obtained curves of evaporation flux in function of the moisture content provided significant values helpful for a better understanding of these phenomena and as input information for simulation.