Masonry Desalination

The principle of electro osmosis was discovered in 1809 by the German physicist F.F. Reuss.

There have been many patented processes utilizing “electro osmotic” principles to dry masonry but few have stood the test of time.

Australia had previously experienced passive electro osmotic systems using copper anodes and cathodes during the late 1960’s and early 1970’s but with limited success and apparent anode depletion.

In 1978 Mr. Gerald Adams, in the U.K., an engineer specializing in cathodic protection systems, developed the “Lectros” system based on platinized titanium anodes connected to titanium connecting wire. The purpose designed power supply took into consideration important criteria such as current, voltage and anode longevity.

In 1999 the Lectros System was introduced to Australia. Due to the incompatibility of the U.K. power unit with local electrical standards and requirements, a new control unit was developed in Australia, based on the U.K. output specifications, to work in conjunction with locally available approved “plug pack” transformers. Incorporating digital displays, changes in voltage and current are constantly illustrated providing a visual reference to the changes in moisture content via the variable electrical resistance and effects on the systems electrical charge. Minimal regulated D.C. voltage requirements and current restrictions, mA) provide an effective moisture and desalination system to arrest decay caused by rising damp and active salt content problems.

The Lectros Electro Osmotic System for the drying and desalination of masonry has enjoyed 30 years of successful usage and has being installed internationally for many years with unrivalled success.

The importance of brick and natural stone desalination has sadly been underrated. Constant masonry moisture content is rarely a problem where the masonry extends below ground level, however, where the masonry is above grade the wetting/drying cycle causes an expansion/contraction cycle of the contained salts which induces fretting and disintegration of the masonry, (clay brick and/or natural stone), and mortar.

Mr. David Young, O.A.M, B. App. Sc., Heritage Consultant, has been an advocate of desalinating masonry to remove the hygroscopic salt content and has published a paper entitled “Get the Salt Out”. Davids’ knowledge and experience in the conservation of Heritage Buildings has resulted in his conclusion that the importance of desalination ranks as high as the reduction of moisture content.

Download “Get the Salt Out” PDF

Lisbeth M. Ottosen, (Associate Professor, Technical University of Denmark, Department of Civil Engineering), has published a number of papers and her endeavours have been totally independent and without any knowledge of the Lectros E.O. System:

Lisbeths paper “Drying Brick Masonry by Electro-Osmosis” concludes:

“The electro-osmotic transport of water seemed more efficient in pilot scale than in laboratory scale, and in pilot scale it was possible to collect water underneath the cathode after few days of current. Thus the overall concept with water movement in an applied electric field is working.”

Download “Drying Brick Masonry by Electro-Osmosis” PDF

And a further published article by Lisbeth M. Ottosen entitled “Salt-Related Problems in Brick Masonry and Electrokinetic Removal of Salts” also concludes:

“We have shown that it is possible to remove chlorides and nitrates from bricks in the laboratory using an applied electric DC field. The initial salt concentrations in the bricks would have been considered problematic but after electrokinetic treatment non-problematic salt concentrations were achieved. Electrokinetic removal of salts from the masonry of an old stable wall was trialled and it was seen from preliminary results that here both chlorides and nitrates were removed from the masonry.”

Download “Salt-Related Problems in Brick Masonry and Electrokinetic Removal of Salts” PDF

Additional papers published by Lisbeth M Ottosen:

Download “Electrokinetic Removal of Ca(NO3)2 from Bricks to avoid Salt-induced Decay” PDF

View Lisbeth M Ottosens’ Publications Reference:

Additional Lectros references - why_lectros.htm