Water absorption in a fired-clay brick observed by NMR scanning

The water absorption of fired-clay brick has been investigated by nuclear magnetic resonance scanning of one-dimensional moisture concentration profiles. Because of the large amount of paramagnetic ions present in these materials, the hydrogen nuclei have a very short transverse relaxation time and a broad resonance line width. Therefore standard imaging techniques cannot be applied. This paper presents the first quantitative study on these materials using nuclear magnetic resonance. It is found that the overall behaviour of the moisture diffusivity for absorption of all investigated fired-clay bricks can be approximated by an exponential function of the moisture content.