Cathodic protection has been pursued in the UK as a solution to corrosion of structural steelwork in buildings behind masonry cladding (terracotta, Portland  stone).  It supposedly works where there is mortar infill, so that there is an electrical path through the moisture containing mortar (don't need a lot of moisture).

Taylor Woodrow have been very active in pioneering this application, as indeed they were involved in the original pioneering work in developing cathodic protection.

Ove Arup & Partners (a branch of whom I work for) specified this work on a 1920s Portland stone (limestone) clad office building in the City of London.  The works have been done, and are  now the subject of monitoring.  Within 3 years we will know more about the process.

Nevertheless, whether it really will work long term or not, is anybody's guess.  And it is actually quite intrusive because you have to insert the anodes ... drill holes, grind out joints etc as a minimum, remove stone and replace in the worst case.  Only advantage is you don't have to clean back the steel and apply conventional protection.

English Heritage did a project with a 17th Century stone gateway involving cathodic protection of individual steel cramps.  Still being monitored.  ONe of the EH people who were involved in this is now working in Australia, and I have had discussions with her about the process.  Paper on this work published as:

Blackney, K. and Martin, B.  (1998) "Case study: the application of cathodic protection to historic buildings: buried metal cramp conservation in the Inigo Jones Gateway, Chiswick House grounds, London" in English Heritage Research Transactions Volume 1 Metals.  April 1998. pp 83-94.

Available from English Heritage (check their website)

http://www.english-heritage.org.uk/

We were looking at it as a potential solution for corroding structural steelwork behind limestone cladding.  Still looking, but we want to wait another ten years to see how successful it really is.

I am concerned that it may cost more than conventional repair, and not perform as well in the long term, even though it might result in a little less disturbance of the fabric.

Cheers

david

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david west
Arup Facade Engineering
477 Kent Street, Sydney  NSW  2000
PO Box Q116, QVB Post Office  NSW  1230
Australia
Tel:  +61 (02) 9320 9447
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