Jul 29, 2021 | Salt Sense

Gritting Roads in Hot Weather

During cold winter weather, salt gritters are a common sight on the roads in the UK. Salt is used widely to keep our roads ice free so that traffic can move freely and safely.  In fact, every £1 spent on winter road maintenance is estimated to save the UK economy approximately £8!

The UK’s fleet of road gritters are not entirely out of action during the summer months, however.  Salt is also used when roads are risk of “melting” during particularly hot weather.

The properties of salt make it ideal for de-icing roads as it lowers the freezing point of water, which makes freezing temperature of water drop and forces ice to melt. In hot weather, salt plays a slightly different role in protecting our road surfaces and ensuring safe driving conditions.

When roads hit temperatures of around 50 degrees Celsius tarmac can begin to soften. To put that into perspective, if the outside temperature is in the high 20s, this can be enough for the roads to reach 50C, since dark asphalt absorbs heat and will steadily raise in temperature throughout the day.  This can result in roads becoming sticky and more vulnerable to pressure from heavy vehicles.

Whilst this is a relatively rare occurrence in the UK, there have been instances of roads in the UK having to be closed due to melting tarmac during heatwaves. Councils closely monitor the temperatures of our roads and will be on the lookout for signs of ‘binder flushing’, which makes the roads appear blacker than usual.

Spreading salt on the roads helps to stabilise the road surface by absorbing bitumen from the surface.  It also provides a protective layer that helps to protect both the road and cars from damage.

So next time you see a gritter out and about on a hot summer’s day, you’ll know what’s it’s up to!

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