Magnetic resonance and magnetic resonance imaging measurements of porous media: fluid quantification and magnetic susceptibility contrast

Abstract

Magnetic Resonance (MR) and Magnetic Resonance Imaging (MRI) are non-destructive and non-invasive techniques that have been employed to study fluid content in porous materials such as core plugs and cementitious materials. Quantitative imaging of fluid content in porous media is an essential factor in MRI of such systems. Water is intimately involved in the deterioration of structures built with cementitious materials. Quantitative moisture profiles may be acquired in porous media with SPRITE since its local image intensity has simple T[subscript 2]* contrast. In this thesis, MRI studies of unsteady and steady state moisture penetration due to wick action in mortar specimens are presented. The observed MR/MRI signal from mortar samples originated from two water populations, each with different signal characteristics. The interlayer water was spatially resolved for the first time in this work. Water in the pore space is more commonly observed in MR studies. The transport parameters controlling wick action were determined by fitting the moisture profiles through inverse modeling of one-dimensional moisture content profiles with the 1D Hydrus program. Bulk T[subscript 1]-T[subscript 2]* measurement was introduced in this thesis. The T[subscript 1]-T[subscript 2]* measurement is a useful analog to the T[subscript 1]-T[subscript 2] experiment. It is particularly important when an echo-based measurement is challenging due to short T[subscript 2] lifetime. Our previous studies on mortar suggested such samples would be ideal for T[subscript 1]-T[subscript 2]* measurement. Monitoring changes of the T[subscript 1]-T[subscript 2]* coordinate and associated signal revealed information about structural change in the samples under study.