GEOTECH DE is the membrane that insulates rails from electrical currents and stops the dispersion of current to the ground. GEOTECH DE has a very high dielectric strength (CEI 15-1: 192 VK/cm) and also a very high volume resistivity (CEI 15-23: 486,8 T cm) that make it an optimal electrical insulator. As GEOTECH DE is waterproof and does not absorb humidity its electrical resistance remains unaltered in time. It is resistant to site traffic and to the friction between the concrete surfaces where it is installed because it is reinforced with elastic, rot-proof, puncture-resistant, non-woven single strand Spunbond polyester fabric.
GEOTECH DE is resistant to acids, inorganic bases to mold, and bacteria. The proposed conform layer build-up is also resistant to the oils, greases, and hydrocarbons which it can be expected to come into contact with, in its specific use. The autogenous welding of the overlaps means no adhesives are used with different electric resistance, guaranteeing the homogeneity and continuity of the protection against stray currents. GEOTECH DE also protects metallic structures on which it is bonded against corrosion as it is resistant to the acidity of the ground, is waterproof, does not absorb water, and forms an effective vapor barrier against water vapor and oxygen. The top face of the membrane is coated with a uniformly distributed, fine serigraphs talc, a patented treatment that makes it possible to quickly unroll the rolls and install the membranes with the reliable and quick welding of the joints. The underside of the membrane is coated with Flamina, a plastic film that melts when torched producing a strong bond over the entire surface area.
Dispersed dielectric currents are also known as “stray currents” form in the ground near electric rail and tram lines. In DC electrified lines the current supplied by the sub-station runs through the overhead lines, supplying electrical energy to the electric motors of the trains and trams or returning to the sub-station, mostly through the rails but also through the ground near the tracks where a certain quantity of electricity is dispersed. If there are metal pipes in the ground, the dispersed current runs along these pipes until it reaches the vicinity of the electric rail and tram line sub-station causing interference in the pipes with the formation of a positively charged cathode where the current enters and a negatively charged cathode where it leaves with the relevant corrosion. Alternating current electric lines may also generate the same kind of phenomena although on a less intense scale. The corrosion produced by stray currents is much greater than that produced by galvanic currents that generate when different metals come into contact or by the same metals in different atmospheric conditions) as the intensity of the current can reach tens of amperes. A current of 1 Ampere corrodes 9 kg of iron and 33.6 kg of lead in one year. Pipes can be protected against corrosion with active or cathode protection, or with passive protection, in other words with suitable coatings. However, when a new rail or tram line is built in a residential area where the position of old underground installations is unknown or it is impossible to reach, obviously it will be necessary to keep the dispersion of electric current in the ground to a minimum. Instead of insulating the underground installations, it will be necessary to insulate the rails of the electrified lines to contain the dispersion. Electrochemical corrosion can also be triggered by the mains earth circuit of a metal tank resting on the ground.
