How do they lay tarmac uphill without it running downhill before it sets?
Question:
Answers:
liquids roll downhill.
Tarmac is never a liquid.
It is granuals of granite covered in tar. With hot tar they are melted and pushed together. The tar never really gets liquid enough to flow anywhere. You can walk on hot tar immediately after the roller, it cools rapidly to a solid finish.
Going over it with a steam roller compacts it and also slightly drys it so it isn't as plyable.
Tarmac isnt that runny mate.
If you go to Holland you'll notice that it's flat, this is because the tarmac ran down all the hills so often that there were none left.
OK I'm a silly person, but I did enjoy reading the correct answer about the steam roller.
tarmac is very viscous (thick and slow to move) so it needs shaping to make it spread properly in the first place. if the gradient (angle) of the hill was steep enough to worry about the tarmac running then it would be too steep to drive on.
Tarmac is primarily crushed stone - the tar is only a binding agent. Crushed stone won't flow downhill, whether tar has set yet or not.
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