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Freeze‐Dried and Critical‐Point‐Dried Clay — A Comparison
Author(s) -
Murray R. S.,
Quirk J. P.
Publication year - 1980
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1980.03615995004400020003x
Subject(s) - freeze drying , capillary action , suction , swelling , mercury intrusion porosimetry , porosity , swell , water content , materials science , mineralogy , moisture , chemistry , geotechnical engineering , geology , soil science , chromatography , porous medium , composite material , thermodynamics , physics , oceanography
The results of experiments conducted with an illitic soil, which has been freeze‐dried and critical‐point‐dried, confirm that the freeze‐drying process fails to preserve the structure of the swollen material. The pore structures, associated with clay “domains” (<10 nm), in samples freeze‐dried from a wide range of soil‐moisture potential, are improbably similar to that of an air‐dried sample. In addition, the presence of large pores (about 1 µm), which should have drained at the equilibrium suctions, in the normal swelling range, which the samples experienced prior to freeze‐drying, is inconsistent with the capillary rise equation. Furthermore, soil which has been freeze‐dried from 10 kPa suction swells when placed at 5 MPa suction ( p / p 0 = 0.96). During mercury intrusion, freeze‐dried samples retain most of their total porosity while critical‐point‐dried samples collapse; this collapse is thought to be consistent with the metastable nature of a dry, but swollen, clay structure.