What is it with new tarmac
 

Came home from work this morning and nearly had a bit of a moment turning into my road. They've relayed the next road along and living on a hill with a park at the top which has been waterlogged since the snow has a river running down it didnt notice the colour of the road till I dropped the car back to the wife this morning. Seems all around the new tarmac is covered with either oil or diesel which has washed down and been spread out by the cars so all the back streets near me are multi coloured rainbows. Are they allowed to do this and try to take as many of us Motorcyclists out as possibile??

Re: What is it with new tarmac
 

Oil from the tar takes a few good rainfalls to clear-----treat with extreme care

Re: What is it with new tarmac
 

Are you sure it's diesel & not just the oily residue that comes out of all new tarmac?



Edit - Bugga DT beat me to it!!!

Re: What is it with new tarmac
 

They relaid some of the Caerphilly Relief Road last year and they put a warning sign up as the new stuff would still be slippery - it's 60mph and a long sweeping bend. I always take it easy going around on the bike, and I've seen at least one car who didn't and slid into the curb and popped his tire.

Re: What is it with new tarmac
 

I've heard that some road layers purposely spray diesel onto tarmac to keep the top layer softer for final rolling, it doesn't harden off as quick and gives a better final finish. Naturally it doesn't all seep through and some will be left swilling around on the top when it rains.

Re: What is it with new tarmac
 

Diesel is usually used as an anti-sticking agent so the rollers and other metal bits used don't pull lumps of tar out of the road. It doesn't really soften it that much. After a couple of showers and a bit of wear it is normally okay. But Oil and fuel does tend to lay on it a bit more with it not being as porous as older tarmac.

Re: What is it with new tarmac
 

Thanks for the clarification as to why they spray diesel on the tarmac.

Re: What is it with new tarmac
 

I'm not an expert so feel free to take this with a pinch of limestone, but I was told that there's another factor as well as the diesel used in laying. Tarmac is made of stone grains coated in tar. When it's first laid you're riding on that nice slippy tar. When it's been used for a while the tar wears off leaving the stone grains sticking up which increases grip, particularly in the wet.

Any civil engineers like to comment?

Re: What is it with new tarmac
 

Great! :roll: so if we're not complaining about potholes, we're complaining about the new tarmac ](*,)

Re: What is it with new tarmac
 

I seem to recall that there is a specific issue with SMA (Stone Mastic Asphalt?). A few cases of fatalities attributed to it. Friction is low even in the dry when relatively new. I'm sure the details are out there on t'interweb.