Oedometric Small Angle Neutron Scattering: In-Situ Observation of Deformation Partitioning in Clay-rich Samples

We present novel oedometric small angle neutron scattering (SANS) on deforming clay-rich materials. Oedometric SANS involves a non-hydrostatic pressure vessel (i.e., the oedometer) that places a porous sample under uniaxial strain with control of applied pore pressure. The oedometer is optimized for neutron optics of SANS on the Low-Q Diffractometer of the Los Alamos Neutron Science Center. The device enables normal oedometric measurements of time-dependent compaction, but with SANS for in situ observation of pore structure evolution under uniaxial strain as a function of effective stress and pore fluid compositions. We present preliminary examination of clay compaction and testing of the device. Funding from the DOE Basic Energy Sciences Geosciences Program is gratefully acknowledged. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.