Thesis or dissertation
Date of this Version
Many pre- to late-nineteenth century brick masonry structures encountered by conservation professionals are constructed with hygroscopic, porous brick that has been attacked by the combination of moisture and salt. The presence of these enabling factors of deterioration accelerates damage to a brick. Professionals need an affordable nondestructive tool that does not require extensive calibrations to highlight dangerous levels of moisture in the presence of soluble salts at a macroscopic scale prior to evident material loss. The infrared camera has been proven to display a visual image of moisture anomalies in a brick wall, but quantification requires spot readings with a moisture meter and accurate quantification requires sampling and laboratory testing. This paper investigates whether an infrared camera can be used to quantitatively determine in situ moisture content of a porous brick wall. In achieving this, a testing procedure was developed and performed on thirty-two hand-molded colonial face brick cuboid samples conditioned to four equilibrium moisture contents. The results of this test concluded that infrared thermography can distinguish different levels of moisture content with the thermal images. Secondly, there exists a linear relationship between ∆T surface center point and measured moisture content as well as a similar relationship between ∆T average surface and measured moisture content when room %RH is lower than equilibrium %RH for the sample. The linear relationship of measured moisture content and ∆T may be consulted for determining moisture content readings in different ambient conditions; however, nearly saturated samples require further study.
infrared thermography, measured moisture content, brick, salt, non-destructive testing (NDT)
Date Posted: 03 September 2014