BEHAVIOUR OF ALUMINIUM GALVANIC ANODES IN SOIL

Aluminium anodes, widely used in sea water, are not specified for soil because of their tendency to passivate in environments with chloride content below 5,000 ppm. However, there are chloride contaminated soil where aluminium bracelet anodes could be of interest. Based on this possible option, an experimental research program started, with the aim to study the effectiveness of aluminium anodes in low chloride content solutions. The research followed two phases: laboratory tests and field tests. The latter were performed in the CNR IENI facilities in Bonassola, Italy, using natural sea water (Ligurian Sea). Laboratory tests were carried out in solution with different chlorides concentration and in sulphate solution with the same conductivity. Field tests were performed in soil saturated with chloride solutions (2,000, 6,000 and 19,000 ppm chlorides for comparison). For comparison purpose, also zinc anodes were tested. Protection potential and current density were measured and recorded. This paper presents first 6 month testing results in various chloride concentration solutions.