ELECTROSTATIC FORCES BETWEEN CLAY AND CATIONS AS CALCULATED AND INFERRED FROM ELECTRICAL CONDUCTIVITY

EQUIVALENT CONDUCTIVITIES OF ADSORBED CATIONS WERE DETERMINED IN CLAYS SATURATED WITH NA, CS, CA AND WITH MIXTURES OF THESE CATIONS. MEASUREMENTS WERE ALSO MADE ON CA CLAYS WHICH HAD BEEN FORCED BY PREVIOUS DRYING INTO BUNDLES OF PLATELETS OR TACTOIDS. THE AVERAGE MOBILITY OF ADSORBED CA AND CS IS MUCH LOWER THAN THAT OF ADSORBED NA. IT WAS CONCLUDED THAT THE AVERAGE MOBILITY OF ADSORBED CA IS LOW BECAUSE MOST OF THIS CA IS ON THE INTERNAL SURFACES OF TACTOIDS. CA ADSORBED BETWEEN THESE INTERNAL SURFACES APPEARS TO HAVE A MOBILITY MUCH LOWER THAN CA ON THE EXTERNAL SURFACES WHICH HAS A MOBILITY OF THE SAME ORDER OF MAGNITUDE AS NA. POLARIZATION OF ADSORBED CS ACCOUNTS AT LEAST PARTIALLY FOR ITS LOW MOBILITY IN THESE CLAYS. DEMIXING OF ADSORBED CATIONS /SEGREGATION WITH NA DOMINANT BETWEEN SOME PLATELETS AND CA BETWEEN OTHERS/ IS SUGGESTED AS AN INITIAL STEP LEADING TO BREAKUP OF NA-CA CLAY MASS INTO TACTOIDS. THE TACTOID MODEL, WITH CA AND NA PREFERENTIALLY ON THE INTERNAL AND EXTERNAL SURFACES RESPECTIVELY, FURNISHES AN EXPLANATION OF THE INSTABILITY OF CLAY AND SOIL AGGREGATES WITH 15 PERCENT EXCHANGEABLE SODIUM. /AUTHOR/

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Filing Info

  • Accession Number: 00237372
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 5 1994 12:00AM