Active thermography for the characterization of surfaces and interfaces of historic masonry structures

Influences from environment are inducing structural damage, modification of materials and agglomeration of pollutants, salt and microorganisms which first become visible at outer or inner surfaces of historic buildings. Non-destructive testing methods and especially active thermography are well suited for assessing and monitoring the condition and modification of facades. Active thermography methods with a selective heating of the surface enable structural and material investigations from one side of building elements up to a depth of about 10 cm. In this paper, results of case studies will be presented concerning the detection of subsurface defects and moisture.