@ebarchuleta1 asked 5 months ago.

If the sun shines on tarmac at 30degrees c. how hot does the tarmac get?

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@Juliann answered 4 months ago.

Most roads are made of tarmac, or asphalt, which is a semi-solid material that starts softening at 122F (50C). While this is higher than average UK summer temperatures, under direct sunlight the dark material rapidly heats up.

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@clarkee answered 5 months ago.

Why does Tarmac melt in hot weather?

 

 

Most roads are made of tarmac, or asphalt, which is a semi-solid material that starts softening at 122F (50C).

 

While this is higher than average UK summer temperatures, under direct sunlight the dark material rapidly heats up.

 

When air temperatures outside are just 77F (25C), asphalt in the sun has been measured at 125F (51C). 

 

Tarmac is 'viscoelastic' which means that as a solid it's very sturdy but it can also transition back to a liquid. This makes it's easy to work with but also makes it susceptible to melting in unusually hot weather.

 

As temperatures rise, the material softens, meaning it can sink under the weight of heavy vehicles. Melting generally only affects the top later which is from 1.2in (3cm) to 2in (5cm) thick. 

 

However, on roads with lots of traffic this course layer can be thicker. In order to stop sticky roads, local authorities send out gritters to absorb some of this soft material. Once the temperatures decline the road becomes hard again.

 

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@jack answered 5 months ago.

The answer is that the tarmac would only get as hot as the air temperature, which is around 30 degrees Celsius. The reason being that the sunlight is absorbed by the dark tarmac and turned into heat.
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