The use of Cu/CuSO₄ potential probes for monitoring the effectiveness of cathodic protection on buried metallic structures and infrastructures, such as gas pipelines, is increasingly widespread. A known issue related to the use of buried electrodes is the slow diffusion-driven release of copper sulfate through the porous junction of the electrode, typically made of ceramic material. To reduce or prevent this phenomenon, which over time leads to instability and malfunction of the electrode, solutions have recently been proposed that mainly involve the use of solid or semi-solid (gel) backfill materials, still based on copper sulfate. This paper discusses the results of laboratory tests conducted on various mixtures formulated with organic and inorganic binders combined with hygroscopic fillers with high water retention capacity, such as clay and cellulose, in addition to copper sulfate. The mixtures were evaluated based on their paste fluidity, setting time, dimensional stability, ionic conductivity, and potential stability.
