This study presents a method to determine surface relaxivity in soft sediments by combining one-dimensional Nuclear Magnetic Resonance (NMR) imaging with particle size and shape estimates. In order to determine the surface relaxivity up to now often methods like Mercury Intrusion Porosimetry or Brunauer–Emmett–Teller (BET) are used which where drying steps are involved which can alter material properties during analysis, particularly in highly deformable materials, making these techniques unreliable for soft soils. By combining NMR relaxometry and estimates of particle sizes and shapes of a soft soil, this new approach provides accurate, non-invasive surface relaxivity measurements. This method is demonstrated on kaolinite, glass beads, and natural soils, showing that this method supports detailed assessment of pore size distributions in soft sediments, benefiting geotechnical and environmental research where soil stability is critical.

This study introduces a fast 1D nuclear magnetic resonance (NMR) imaging method based on multi-slice imaging with a stepper motor to study sedimentation dynamics of clayey soils. Traditional NMR is limited by long acquisition times due to water’s T₁ relaxation time. Our approach combines multi-slice imaging with a stepper motor and frequency-based selection, reducing measurement time while maintaining sub-millimeter resolution, at the same time overcoming the limitations by the slow relaxation of water. This nondestructive method provides detailed insights into the sedimentation and consolidation of suspensions, including pore size distribution and density profiles within a single measurement. The technique is demonstrated with kaolinite clay suspensions, highlighting the technique’s ability to capture the dynamics of gravity-driven systems rapidly and accurately, even for fast-sedimenting soils such as kaolinite in the first hours of sedimentation. This advancement is valuable for geotechnical and environmental applications where understanding sedimentation is crucial.