Cathodic protection of steel framed masonry structures.

The identification of "Regent Street Disease" in the United Kingdom in the late 1970's highlighted the problems of the corrosion of iron and steel frames and other structural components in historically sensitive buildings. This has resulted in serious consequences with respect to serviceability, safety, aesthetics and heritage.Cathodic protection is a proven method for preventing and protecting buried and submerged steel and reinforced concrete structures from corrosion. More recently, the method has been introduced to prevent and control corrosion in steel-framed masonry structures. However, with several sizeable installations in the UK, there are no formal guidelines for the design, installation and operation of such systems and much of the knowledge is based on empirical observations. The work presented in the thesis investigates the polarisation of structural steel sections in masonry environments; the distribution of current and potential in representative cathodic protection systems for steel-framed masonry structures; the effect of masonry type and joints width on protective current and potential distribution and stray current corrosion. These studies are considered essential in the understanding of the mechanisms of cathodic protection and the design of optimised cathodic protection systems for such structures. The study has involved both experimental measurements and boundary element modelling. The results have identified how the several key factors, such as the electrolyte resitivity, anode locations, masonry types and joint width, influence the distribution of the protective current and potential on the steel surface.Furthermore, the work has confirmed that boundary element modelling can provide a powerful technique for analysing and optimising the design of cathodic protection systems for steel framed masonry structures. The technique also generates valuable information about the level of interference in terms of current density on the surface of stray current affected components and is therefore a valuable tool for the analysis of possible CP interference in steel-framed masonry buildings.It is hoped that the output from this work will help progress the development of this technology and contribute to the development of formal guidelines and standards for the cathodic protection of steel-framed masonry buildings.