The 75% the collapses of street lighting poles is due to rust that rots the foundations jeopardize the solidity, with serious danger to people and property.
Normally the rust starts from the base, there where the pile out of the ground, which it is the most vulnerable point by stress corrosion Differential (between underground and surface), of dog droppings, of the exhaust gas of the car, the stagnation of water etc.. Little need the maintenance remedies (if and when they are executed); it is better to intervene before upstream claiming that managers of public affairs require installation of piles with a duration of at least 30-40 years before Servicing.
Some examples of corroded poles help to understand the gravity of the phenomenon:
In this case, It is the porosity of the cement because of the round iron corrosion. An effective remedy is to sandblast, Zinc spray and cover with more concrete, on whose surface rispruzzare zinc that goes to fill the holes and that prevents the entry of external contaminants.
By their nature, paints perform an action of simple passive and not anodic coverage, for which the rust appears immediately.
Zinc, instead, also it has the function anodic than steel, consumed in his place at a speed 10-12 times lower.
The poles galvanized begin to rust after a while because the deposited zinc does not exceed 60-70 microns of which only 25-30 Micron's pure zinc (the rest are Fe / Zn alloys). Everyone knows that the rust resistance depends on the thickness of zinc; plus it is high, the greater the duration. Against rust the galvanizing spray is the most effective system, durable, cheap and it's the only one that guarantees zinc thickness up to 500 micron.
For the poles galvanized, as it is used in Northern Europe, it is recommended to increase the thickness at the base with spray galvanizing, that way you will limit costly periodic maintenance, the application of bitumen and metal collars bands which are palliatives because, right after, the rust reform.
In Italy the galvanizing spray spreads quickly because the major pipe mills produce pipes by profiling of galvanized coils, whose longitudinal weld is covered continuously with guns that spray zinc.
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