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The pH influence on the index properties of clays

Article

Abstract

Three clay sediments, concerning Pliocenic clay, Chaotic Complex clay and commercial kaolinic clay, have been studied in order to verify the pH influence on the index properties. The analysed clays have been mineralogically characterized in natural, conditions, and in modified pH conditions. This last procedure, obtained respectively by adding NH4OH or CH3COOH 1 mol., in a pH range between 4.5–11.3 has been carried out. To verify the different experimental conditions the C.E.C. of exchangeable cations as K+, Na+, Ca++ and Mg++, has been measured. The index properties obtained show a different behaviour of the three clays. The kaolin is not much affected only a limited WL% increase is recognizable when the pH decreases. The Chaotic complex clay evidence a considerable rise of the WL with the pH uncrease. In the Pliocenic clay the WL value increased with the pH. The described process can be related to the natural environment, connected also with various pollution phenomena.

Keywords

Clay Debris Flow Kaolinite Kaolin Liquid Limit 

Influence du pH sur les propriétés des argiles

Résumé

Trois sédiments argileux: une argile pliocène, une argile appartenant à un complexe argileux et une argile kaolinique du commerce ont été étudiés en vue de vérifier l'influence du pH sur leurs propriétés. Les argiles étudiées ont été analysées dans les conditions naturelles eet dans des conditions de pH modifié. Ce dernier processus, obtenu en ajoutant respectivement NH4OH ou CH3COOH conduit à des pH variant de 4,5 à 11,3. Pour vérifier les différentes conditions expérimentales, le C.E.C. des cations échangeables tels que K+, Na+, Ca++ et Mg++ a été mesuré. Les caractéristiques mesurées montrent que les trois argiles ont des comportements différents. Le kaolin est peu affecté, on ne constate, qu'une augmentation limitée de WL quand le pH diminue. L'argile du complexe argileux affiche une augmentation considérable du WL quand le pH augmente. Dans l'argile pliocène WL augmente moyennement en fonction du pH. Le processus décrit peut être relié à l'environnement naturel ainsi qu'à différents phénomènes liés à la pollution.

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Copyright information

© International Association of Engineering Geology 1994

Authors and Affiliations

  • U. Gori
    • 1
  1. 1.Institute of Applied GeologyUniversity of UrbinoItaly

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