STUDY ON THE MECHANISM OF CONSISTENSY CHARACTERISTICS OF NA–MONTOMORILLONITE USING SMALL-ANGLE X-RAY SCATTERING METHOD

Abstract

Type Tests using small-angle X-ray scattering method were conducted to elucidate the mechanism of consistency in Na–montmorillonite. It is possible to analyze the particle structure at the nanometer level using the small-angle X-ray scattering method, which enables measurement exceeding basal spacing of 10 nm, which is not possible in XRD. Based on the test results, in the solid state to semi-solid state, there was crystalline swelling in which the molecular water layer thickness increased stepwise, whereas in the plastic state to liquid state, there was osmotic swelling in which the distance between particles continually increased. Moreover, near the plastic limit, the basal spacing increased rapidly from a 3-mol-thick water layer to a 12-mol-thick water layer; furthermore, as the liquid limit approached, the basal spacing increased up to the order of 50-mol-thick water layer. An evaluation of the orientation of the clay particles from the X-ray scattering images revealed that, while the particles were randomly oriented in the solid state to semi-solid state, they became oriented ordered in the plastic state. Furthermore, in the liquid state, it was observed that the particle orientation became random again.