When it comes to making a choice of paving material for a particular job. The two contenders will normally be asphalt or concrete. This does not mean that you have a limited choice. Within these two materials is a high level of diversity. There are different types of concrete and asphalt as well as different methods of application. However, if ice and snow are something you have to contend with, and especially when we are talking about roads which heavy vehicles can be expected to drive over at speed asphalt is normally the clear choice.
Parking Lot Pros, asphalt, and concrete paving experts out of Dallas, Texas, say that the reason asphalt is suitable for icy and snowy conditions is that it offers better traction when in contact with vehicle tires. There are even distinct types of asphalt, such as warm-mix asphalt (WMA) and, more recently, cold mix asphalt (CMA), which can be laid down even in cold conditions. Accordingly, asphalt is often used in cold places where maximum traction on roads is a safety imperative.
The Salt Question
Another material that you will be familiar with if you have ever undertaken a paving or road maintenance job in cold places is grit salt. Grit salt is applied as a deicer to remove ice from surfaces. Nevertheless, you may more readily associate grit with concrete surfaces and not asphalt. There is a good reason for this. Asphalt paving is known to be weather- and ice-resistant and you may even have heard that applying grit salt can actually damage asphalt surfaces.
These impressions do not come from anywhere. In fact, grit salt can damage asphalt. However, a smooth, freshly layered, and unbroken asphalt surface is unlikely to be damaged by grit salt. Instead, it is dangerous in the very many cases where there are existing cracks and potholes, as it can make these much worse.
The Freeze-Thaw Cycle
The reason grit salt can be perilous for asphalt roads with existing cracks is all down to something called the freeze-thaw cycle. This is when cracks accumulate water, the water freezes into ice under cold weather conditions and then expands, which widens the cracks. When the ice melts again back into the water, this opens a new, larger, cavity ready to be filled again with water and expanded all over again. Grit salt is known to exacerbate the process because it melts the ice in the cracks, which simply allows said cracks to collect water again, ready to freeze and worsen the cracks. By using grit salt on degraded asphalt pavements, you are increasing the number of freeze-thaw cycles every winter.
Can You Use Grit Salt on Asphalt?
Nonetheless, this does not actually mean that you can never use grit salt on asphalt pavements. Moreover, it does not even mean that it will not sometimes be necessary to do so. Asphalt is resistant to ice but, under conditions of heavy snowfall, there can be enough snow accumulated (and compressed by vehicles) to create an icy layer, even over asphalt.
The way to avoid the negative effects of salting, therefore, is to apply it intelligently, avoiding the areas with excessive cracks if at all possible. Better yet, you can replenish your asphalt surface with a new layer of asphalt, removing the cracks altogether and making it safe from salt. As another solution, you can also try reducing the amount of salt you use by mixing it with sand.
Ultimately, salt is sometimes necessary, but it can indeed damage your asphalt surface. A little preparation and forethought though can easily ameliorate the problem.