Electrokinetic strengthening of soft clay using the anode depolarization method

Original Paper

Abstract

Electrokinetic stabilization is an innovative and cost effective ground improvement method for soft soils. With this method, stabilizing agents are electrically injected into the soils to achieve stabilization by means of ion exchange, precipitation or mineralization. The method is not yet widely accepted for common application as it improves the strength of soils only within a limited area. When coupled with a depolarization technique, the quality of the soil improvement is enhanced. Calcium ions are electrically injected into soils to replace monovalent ions while hydrogen ions, generated from electrolysis at the anode, are prevented from migrating into soils by continuous depolarization at the anode reservoir. However, hydroxide ions, generated at the cathode, are able to migrate into the soils. The injected calcium ions and hydroxide ions react with the dissolved silicates and aluminates in the clay to form cementing agents—calcium silicates and/or aluminum hydrates. Increases in strength of up to 170% immediately after treatment and up to 570% after a 7-day curing were measured. These results demonstrate that this simple technique could significantly improve the quality of electrokinetic stabilization in soft soils.

Keywords

Ground improvement Soft ground Electrokinetic stabilization Electrochemical stabilization 

Résumé

La stabilisation électrocinétique est une méthode innovante et économique d’amélioration des sols mous. Par cette méthode, des agents chimiques sont injectés électriquement dans le sol pour obtenir une stabilisation grâce à des processus d’échanges ioniques, de précipitation et de minéralisation. La méthode n’est pas encore largement appliquée dans la mesure où l’amélioration de la résistance du sol ne se réalise que dans une zone limitée. Les ions calcium sont électriquement injectés dans le sol et remplacent des ions monovalents, tandis que les ions hydrogène, résultant de l’électrolyse et produits à l’anode, ne peuvent migrer dans le sol du fait de la dépolarisation continue à l’anode. Cependant, les ions hydroxyde, produits à la cathode, peuvent migrer dans le sol. Les ions calcium injectés et les ions hydroxyde réagissent avec les silicates et aluminates dissous, provenant des argiles, pour former des agents de cimentation – des silicates de calcium et/ou des hydrates d’aluminium. Des augmentations de résistance jusqu’à 170% immédiatement après le traitement et jusqu’à 570% après un traitement de 7 jours ont été mesurées. Ces résultats démontrent que cette technique simple pourrait améliorer de façon significative la qualité de la stabilisation électrocinétique des sols mous.

Mots clés

Amélioration des sols Sols mous Stabilisation électrocinétique Stabilisation électrochimique 

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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.GTE Program, School of Civil EngineeringAsian Institute of TechnologyKlong Luang, PathumthaniThailand

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