New ‘Automatic Lightning Conductor Method of Applying Cathodic Protection’ to Metallic and Reinforced Concrete Constructions: Use of Atmospheric Electricity: I. Laboratory and pre-pilot plant scale tests

In the present work, a new automatic method of applying cathodic protection, by using atmospheric electricity, is introduced. This can be achieved by connecting lightning conductors or needles to the metallic structures or the rei1tforcements of reinforced concrete constructions that are to be protected, by means of diodes allowing only the absorption of electrons.

The protective properties of this arrangement were demonstrated by measuring. the corrosion potential of steel tubes in distilled water at 25°c vs time, the weight loss of steel tubes with internal circulation of 3·5% NaCl solution at 70°c in the laboratory, and also when the tubes were buried in soil out-of-doors; the weight loss of the reinforcements of reinforced concrete specimens in circulating sea water at 25°c. The measurements were made in the following conditions. with the specimens connected (or not connected) to lightning conductors in the laboratory and (in a few cases) out-of-doors, or to needles, by means of diodes allowing only the absorption of electrons. In some cases the corrosive environment was connected to lightning conductors by means of diodes allowing only the emission of electrons. In others, the last two arrangements were applied simultaneously.

In subsequent parts of this work the results of pilot plant and full scale tests in natural conditions will be presented.