CAPILLARY WATER MIGRATION IN ROCK - PROCESS AND MATERIAL PROPERTIES EXAMINED BY NMR IMAGING

We report the application of proton nuclear magnetic resonance (NMR) i maging to the measurement of water content distributions in Lepine lim estone, a typical constructional stone. The method is used to observe the kinetics of the absorption of water into this material by capillar ity. The water content distributions are consistent with the predictio ns of unsaturated flow theory. The hydraulic diffusivity of Lepine sto ne is found to be an approximately exponential function of the water c ontent, in agreement with experimental data on other porous materials. The best estimate of the diffusivity function is D(m2 s-1) = 6.3 x 10 (-9) exp(4.90theta(r)), where theta(r) is the normalized volumetric wa ter content. The sorptivity estimated from NMR data is in close agreem ent with the directly measured value (1.00 mm min-1/2). NMR imaging me thods appear promising as a non-destructive and rapid laboratory means of determining moisture distributions, especially for the purpose of accurate measurement of the capillary transport properties of porous m aterials.