Transmission X-ray microscopy (TXM) reveals the nanostructure of a smectite gel.
The unusual behavior of smectites, the ability to change volume when wetted (swelling) or dried (shrinking), makes soil rich in smectites very unstable and dangerous for the building industry because of the movement of building foundations and poor slope stability. These macroscopic properties are dominated by the structural arrangement of the smectites' finest fraction. Here, we show in three dimensions how the swelling phenomenon in smectite, caused by a combination of hydratation and electrostatic forces, may expand the dry smectite volume not 10-fold, as previously thought, but to more than 1000-fold. A new technique, transmission X-ray microscopy, makes it possible to investigate the internal structure and 3-D tomographic reconstruction of clay aggregates. This reveals, for the first time, the smectite gel arrangement in the voluminous cellular tactoid structure within a natural aqueous environment.
Zbik
Marek S
MS
Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane Qld, Australia. zbik@qut.edu.au
Martens
Wayde N
WN
Frost
Ray L
RL
Song
Yen-Fang
YF
Chen
Yi-Ming
YM
Chen
Jian-Hua
JH
D004577:Electron Probe Microanalysis; D005782:Gels / Q000737:chemistry; D018625:Microscopy, Atomic Force; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D017640:Silicates / Q000737:chemistry*
D005782:Gels; D017640:Silicates; C033214:Smectite