How Gritting Affects Concrete in Cold WeatherJanuary 29, 2015
If you own a driveway or walkway and live in a climate that grows cold for any period of time, then you will have experienced icing and slippery concrete.
The hazard of falling is very real and can be a liability – especially true of business owners.
The last thing anyone wants is someone slipping and hurting themselves on the walk. This is why we salt the pavements and driveways, clearing away the ice and creating a safe walking and driving surface. It is necessary to clear ice away, but have you ever thought about the damage you might be doing to the concrete and metal that the salt comes into contact with? Here’s some food for thought about the implications of using salt as a de-icing agent.
Metals rust from oxidization, a process that requires oxygen. We all know that oxygen is in the air around us, but it is also in water. Salt is added to icy roads to de-ice them, essentially lowering the melting point of the ice such that it melts into water. The salt doesn’t disappear, and remains in the slush remaining behind.
The salt in the water is mildly acidic and provides an excellent electrolyte to speed the oxidization of metals. This is a roundabout way of saying that metal in salty water has an excellent chance of developing rust, undermining it’s strength. Most of us associate this with cars but there are metal supports in many concrete structures, such as foundations and bridges. Salt can attack these metals as easily as it attacks cars.
Concrete itself is susceptible to the corrosiveness of chloride ions in salt as well. Although concrete cannot rust, there is an acceleration of wear that can be measured. Far more hazardous is the effects of salt on the metal supports that are added as a matter of course to concrete structures.
Concrete is, by nature, a porous material. Salt water, over time, can ‘soak’ into the holes in concrete and work its way down to corrode at the metal supports within.
Studies being conducted at Chalmers University of Technology in Gothenburg, Sweden, are under way to see just how devastating these effects can be. The time span is measured in years, if not decades, however, so fear of concrete collapsing after sprinkling a little salt on your walk are unfounded. Still, the damage and danger are both real.
The problem with icy concrete goes a little more back to basics as well: cold weather. Contraction and expansion of the ground beneath the concrete and the concrete itself can cause cracks that salt can seep into.
If concrete is measured and mixed correctly from the outset, with the mixing temperature in mind, then the concrete has a higher percentage chance of staying firm and being able to cope with temperatures as they fluctuate.
For the best results in mixing concrete, it is recommended that a Volumetric Concrete Mixer be used. These machines allow for on-the-spot adjustments of the materials used to make up the concrete, allowing for considerations such as weather conditions and temperature to be taken into account.
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