title: The formation of a structural framework in gelled Wyoming bentonite: direct observation in aqueous solutions.
abstract: OBJECTIVE
  Particle space arrangement is a very important factor that determines the physico-mechanical properties of soil. Formations of three-dimensional (3D) structured networks within gelled or flocculated suspension may prevent clay particles and aggregates from settling under gravity force and by encapsulate water within such a network, lead to poor sludge dewatering. To better understand this phenomenon, a microstructural investigation of a smectite clay (SWy2) suspension was conducted.
  
  
  METHODS
  SWy-2 was diluted in water and a moderately salty aqueous solution and was studied with the aid of a synchrotron-powered transmission X-ray microscope (TXM) and cryogenic transmission electron microscope (Cryo-TEM). Observations of mutual particle arrangement in 3D spaces were conducted within a natural water environment after vitrification without drying.
  
  
  RESULTS
  A new type of micro-architecture in particle space arrangement was observed. Smectite flakes were mostly in edge-to-edge (EE) contact and formed a 3D network, confirming a "net of flakes" structural model. Clay particles form a complex and multi-hierarchic flocculated structure with characteristic cellular chained networking. Chained aggregates build cellular elements, encapsulating water inside closed voids. Increasing ionic strength results in the development of multi-hierarchic voids categories, with most water retained within nano-pores.
authors.affiliation: Geotechnical Engineering Centre, The University of Queensland, St Lucia, Brisbane 4072, Australia. Electronic address: m.zbik@uq.edu.au.
authors.forename: Marek S
authors.initials: MS
authors.lastname: Żbik
authors.affiliation: Geotechnical Engineering Centre, The University of Queensland, St Lucia, Brisbane 4072, Australia. Electronic address: D.Williams@uq.edu.au.
authors.forename: David J
authors.initials: DJ
authors.lastname: Williams
authors.affiliation: National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, ROC. Electronic address: song@nsrrc.org.tw.
authors.forename: Yen-Fang
authors.initials: YF
authors.lastname: Song
authors.affiliation: National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan, ROC. Electronic address: wang.jay@nsrrc.org.tw.
authors.forename: Chun-Chieh
authors.initials: CC
authors.lastname: Wang
keywords: Clay flocculation; Clay gelation; Clay microstructure; Colloids; Smectite flocks; Transmission X-ray microscope; Wyoming montmorillonite