I have heard stories of Mississippi River Rock in asphalt that ate a set of teeth in a few hours. Where was the hardest Asphalt that you have milled?
River rock can be very hard on teeth. I think it is because the hardest stuff remains after the river rolls the rest around. The granite and other hard stuff is left over.
Any 4 lane state road entering a large urban area no matter what state was hard. Truck traffic and mix density would have you changing teeth twice before midnite and waiting on trucks because of traffic...
Worland, WY 5 inches of 22 inches. Needed Fuel at 7 hours in.
I did some shoulder work with a 1200 on the future I-22 in MS that had river rock in the mix. The asphalt was reddish and by far the most abrasive/hard asphalt I have ever milled,and it did not take a few hours to ruin a set..more like 1 hour or less. Not only the tooth wear but it was wearing out the sides of the holders. Would probably be a good idea to run a diamond drum on any mainline A distant second to the above experience would be what they called super pave down in Florida.
That superpave isnt too bad if you pour the water too it. Years back doing corrections for APAC on US1 south of Titusville we got into sections that weren't consisent with the majority of that job, our objective of course was ride spec. Other areas we took out werent to bad at all with tons of water on the drum. BTW hot rod mill people, on that job with the worn out RX45 6ft head we could run at 70 to 80 fpm in superpave mix design. nowadays I'd imagine those newer style mills wouldnt be slow in it at all except for burning up teeth.
a random temporary crossover on I76 west of Akron, OH. we used six sets of teeth opening up a 4'x750' hole for drainage tile. a close runner up will be any job i ever did on the gulf coast. that coral or whatever it is in the mix is some nasty crap. 100 degree temps with 90 percent humidity make changing 7 or 8 sets of teeth a REAL treat.
Did a emergency patch for MDOT in Michigan last week and it took 7 hours (3000 sq.ft.) with a mini mill. Changed teeth 3 times and lost 4 holders, never came across anything like it before, used a rx700 on the next section the following week and the top man came down to check the drum after 10 minutes because he thought he found a buried manhole. Not sure what kind of asphalt it was but it was a old back country road that hadn't been replaced in 20 years so wo knows.