- A practical and affordable solution
The advantages of rapid water movement under electroosmosis have historically
been tempered or even negated by electrolytic reactions at the electrodes which
create severe practical problems during electroosmosis. The strongly oxidising
environment and associated low pH cause rapid corrosion of metallic electrodes
(the only historically available choice).
This has meant frequent replacement of the electrode but, more importantly,
increased resistance of the soil/electrode contacts, thus reducing current density
and electrical efficiency.
Electrode corrosion has only been overcome in the past by utilising materials
such as platinum, gold and palladium-titanium alloys – which are very
expensive. EKG materials are corrosion resistant but also affordable.
Owing to their structure and high surface area EKG electrodes have improved
upon the limitations of current density and electrical contact with the soil,
especially during dewatering applications such as ‘wick drains’
or prefabricated vertical drains (PVD).
An EKG electrode can provide all the established functions of conventional geosynthetics
including drainage, reinforcement and filtration. By forming the electrode as
a geosynthetic, EKG overcomes the problem of removing electroosmotically gathered
water by utilising the drainage function of geosynthetics. Additional advantages
are the ability to exploit geosynthetics' traditional reinforcing characteristics
and their ability to take on a wide variety of shapes and forms.
Electroosmosis moves water from the anode to the cathode. Negative porewater
pressures are generated in the region around the anode and these gradually spread
outwards resulting in consolidation. If a more even distribution of consolidation
is required, for example in ground consolidation applications, this can be achieved
by reversing the polarity of the system. EKG electrodes can be made identical
and can therefore act as either cathodes or anodes, which is a significant advance
on previous metallic electrodes.
