Calibration of thermal nondestructive testing methods on mock-up historic masonry

In ancient buildings, knowing the composition and the conservation status of walls is a crucial issue to ensure their durability. The presence of defects or discontinuities could be found using InfraRed Thermography (IRT) with different heating techniques. In order to properly calibrate the thermographic testing procedure, a mock-up wall is studied. The specimen is made of ancient bricks and has defects inside the plaster layer at different depths. Three kinds of heating patterns are delivered on the wall: step, sine wave, and chirp. All the three heating patterns are able to enhance the defect from the sound area after a proper image processing analysis. The differences between each technique are presented with a signal to noise ratio evaluation.