ABSTRACT
The movement of moisture through porous building materials is a complex phenomenon, combining different transport mechanisms. Various advanced measurement techniques have been advocated to improve our fundamental knowledge of these processes and success has been achieved in determining basic moisture transport parameters, such as liquid diffusivity. However, these techniques suffer from several deficiencies which prevent the quantification of macroscopic effects, such as cracks, joints and interfaces. This paper reports the development of a new research facility, designed to address these shortcomings, using high resolution X-ray absorption. The equipment measures the absorption of a finely collimated beam of X-rays which is scanned in two dimensions over a sample. The positioning of the mechanical scanning system is repeatable to within ±0.01 mm. The system allows transient changes can be evaluated in real time. The apparatus was used to measure the liquid water diffusivity of a range of building materials.
