Electrochemical treatments are utilized on historic buildings to extend the life of the structure from corrosion related damages. Corrosion is present in historic buildings which utilize iron or steel in construction and can cause a variety of failures leading to masonry damage, the loss of original fabric, and even death. Traditional repair techniques can temporarily slow the corrosion process but do not provide a long term solution for corrosion.

By utilizing corrosion engineering techniques it is possible to extend the life of the structure before the effects of corrosion have caused irreparable damage. Electrochemical repair techniques mitigate corrosion for an extended period (greater than 25 year life), can be installed without removing masonry cladding, are reversible, and are completely undetectable on the historic façade. In 1990, members of our team were commissioned by Historic Scotland and English Heritage to research corrosion related issues in historic steel frame masonry clad buildings and provide innovative solutions to mitigate corrosion.

The objective of the project was to study what initiates corrosion in buildings, ways of investigating corrosion related damages, and to treat corrosion in a non-traditional manner, i.e. without removing the historic masonry cladding. The case study for this work was St. Andrew’s House, located in Edinburgh, Scotland.

The research and investigations took the tools used in the corrosion industry and applied specific tests and treatments to historic steel frame buildings. Rates of corrosion, polarization tests, steel or section loss, and depth of cover were tested and assessed in association with methods used in historical building surveys. Corrosion related damages, voids and areas of high water content were detected.

Afterwards, invasive techniques were employed to verify the accuracy of the testing. It was discovered that with the proper testing and analysis of data, precise accuracy can be used in predicting when damages will occur (time to cracking models), which areas have suffered more damage, and where different building elements fall within a corrosion risk scale. Repairs were developed around corrosion risk. The work resulted in Historic Scotland’s Technical Advice Notes 20 Corrosion in Masonry Clad Early 20th Century Steel Framed Buildings.

Traditional repair options and replacement can be very costly and cause additional damage to the cladding as it is removed from the structure. Key supporters of the research, English Heritage in particular, and the Department of the Environment were looking for 1) a cost effect solution, 2) a solution which allowed the historic masonry to remain in situ to deal with corrosion and 3) a green solution, not having to manufacture new materials to replace and dispose of damaged pieces.

Impressed Current Cathodic Protection, which is used in pipelines and concrete, was developed and refined for its use in historic buildings in a series of steps. Electrochemical techniques were employed first in the laboratory, then in small scale projects such as the Inigo Jones Gateway, London, and Dublin College Arcade. In 1996, the first full scale installation of an Impressed Current Cathodic Protection System was installed on the Joshua Hoyle Building, Manchester. This is a terra cotta and brick clad structure, which currently houses the Malmaison Hotel.

Since this time, numerous landmarks in England have had systems installed. Our company has installed over 100 systems in the UK. In the US there are eight historic steel frame buildings with impressed current cathodic protection systems. The first installation in the US was on the Marshall Field’s Building in Chicago, IL.

The benefits of the systems have been applauded by English Heritage and the UK Department of the Environment, who have chosen electrochemical treatments as the preferred method of corrosion mitigation in historic buildings. The requirements for a successful installation include understanding historic structures, knowing the necessary electrochemistry for design work, and knowing the limitations of a structure. Not all buildings are suitable candidates.

Electrochemical treatments control the corrosion reaction by utilizing an inert anode within the masonry joints. This anode has no expansive properties and a life of over 100 years. The anodes are connected together with an inert wire and then to a DC power source. The steel frame is connected to the system, as a negative connection termed cathode. This allows the loss of electrons to occur on the controlled anode and hence protect the steel frame as the controlled cathode.

The key to choosing an electrochemical treatment for an historic steel frame building is the early use of a system. Potentially, this can save the owners a great amount of money in repair strategies, preserve irreplaceable historic masonry, and control the corrosion reaction for an infinite period of time.