Why does newly paved asphalt sound so much quieter when driving over it?
In: Engineering
Depends on what the mix is.
A new surface from a dense mix with no voids can be quite noisy (often a high pitched whining noise as you drive over it). This will still be better than an older surface because it’s nice and smooth so you are only getting the noise from the wheels rolling, not any bumping of vibration like you get on an old surface that has been pushed out of shape or patched up.
Some types of asphalt are designed to have open pores in it. This does 2 things: firstly it lets water drain away without ponding on the surface. This is a huge safety benefit because surface water especially on high speed roads can make a massive difference to braking distances (hydroplaning really isn’t fun if your car is moving fast and the one in front is stopped). The other thing the open pores do is absorb a lot of sound because the air pressure doesn’t just reflect back, some gets baffled in the tiny holes in the mix.
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