A collection of field emission scanning electron microscope images of clays, which consist of Kaolinite, Bentonite, a mixture of these two minerals, and the fines from a natural residual soil derived from shale. You can download image collection at the bottom of the page.
Gordon Stone and Joseph Dove, Department of Civil and Environmental Engineering
Nizhou Han and Patricia Dove, Department of Geosciences
Virginia Tech, December 2015
Creation of this image collection was supported by the National Science Foundation under Grant No. 1301124 "Biologically-Inspired Silicification of Fine-Grained Soils.". Any findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of NSF.
Thiel Kaolin Co. and WyoBen, Inc. supplied the Kaolinite and Bentonite minerals, respectively.
Clays were used as received. Samples of the Blacksburg soil were passed through a No. 200 sieve prior to preparation for imaging.
Images were acquired at several "regions" on each sample. Within each region, images were collected at progressively higher magnifications. The image footer provides magnifications (i.e., Mag=1k x) and a bar scale. All images were collected in tiff format with a LEO (Zeiss) 1550 Field Emission Scanning Electron Microscope (FESEM) in the Nano Characterization and Fabrication Laboratory of Virginia Tech's Institute for Critical Sciences and Technologies.
Specimens compacted at optimum moisture, freeze dried, and fractured using a razor blade (tensile fracture). Images collected by Gordon Stone.
Images are included from two samples that are made at progressively higher magnifications. They feature a compacted fabric matrix with a layer of loosely attached particles oriented in the direction of tensile fracture. These images highlight the morphology of Kaolinite, which can be clearly observed at the higher magnifications.
A sample was compacted at optimum moisture and brought to failure in an unconfined compression test. The specimen for imaging was collected from the resulting failure surface, then freeze dried, mounted, and sputter coated. View in the images is of the failure surface.
All images collected by Gordon Stone.
60% Bentonite and 40% Kaolinite by weight, hydrated and mixed together in a slurry then deposited on SEM sample holder. Images are of the mineral layer remaining after air drying.
Bentonite hydrated in a slurry, deposited onto FESEM platen and air dried.
Soil hydrated in a slurry then deposited and air dried on FESEM platen. Soil is of mixed mineralogy consisting of Kaolinite and Illite/Smectite.
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