SnowC

source: Wikipedia

translation: doxa-louise


SNOWCLEARING
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Spreading de-icing materials
At the beginning of precipitations, if the temperature is at the freezing point, the spreading of de-icing salt permits the accumulation to melt, to be subsequently evacuated by the sewage system. This can be the sole snowclearing activity if the quantity of snow is low. This technique is utilised after a large snowstorm, where the most of it has been removed by heavy transport and there is only to eliminate the thin residue on the road.

Salt (sodium chloride) spread out absorbs humidity from air and the surrounding snow, in an endothermique chemical reaction, so that the mixture so formed is a sort of brine. This initial dissolution of salt to form brine will be hastened as circulation gives a more intense mixing. Salt has the property of reducing the freezing point of water and the snow which melts at contact with the brine will remain liquid. However, the concentration of salt will diminish with additional melting, which diminishes its usefulness. Starting at -6 C, there is generally not enough humidity in the air to start the reaction and transport sevices are then forced to switch to a prepared product. Under laboratory conditions, sodium chloride (in large quatities) will stop the formation of ice down to -20 C; at the doses used on roads, the reaction no longer produces desired results at -10 C. The service trucks then spread a mix of salt and abrasives (gravel, sand, scoria, landfill) to make the layer of snow granular enoughto permit sufficient adherence for automobile tires. Other de-icers permit overcoming the shortcomings of salt (humidity absorption, corrosion).


Snow pick-up

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