title: Transmission X-ray microscopy (TXM) reveals the nanostructure of a smectite gel.
abstract: 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.
authors.affiliation: 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
authors.forename: Marek S
authors.initials: MS
authors.lastname: Zbik
authors.forename: Wayde N
authors.initials: WN
authors.lastname: Martens
authors.forename: Ray L
authors.initials: RL
authors.lastname: Frost
authors.forename: Yen-Fang
authors.initials: YF
authors.lastname: Song
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Chen
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Chen
mesh_terms: D004577:Electron Probe Microanalysis; D005782:Gels / Q000737:chemistry; D018625:Microscopy, Atomic Force; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D017640:Silicates / Q000737:chemistry*
chemical_list: D005782:Gels; D017640:Silicates; C033214:Smectite