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View Full Version : Breakdown rolling patterns?



928G Boy
07-03-2008, 11:00 PM
I've never ran a packer on asphalt before but I'm curious about the different patterns that the breakdown operators use. On a highway job I've seen the first breakdown packer in the middle of the lane for the first pass, then when he catches up to the paver, he turns into either the centerline of the road or the edge of pavement. This is so that the little bump created by stopping in the asphalt runs parallel to the direction of traffic, therefore making it less noticable. Then he makes the next pass the same but instead of rolling the middle of the lane he rolls on one of the edges, but overhangs the barrel of the roller about 3" over the edge of pavement.

What are some other patterns? I'm totally clueless about this type of thing. Asphalt's not really my thing I'm more of a concrete and pipe guy but I'm interested in asphalt.

telescooper
07-07-2008, 08:09 PM
I'm not a roller guy either but do operate a paver sometimes and have been on paving crews for about 14 years . I have done just all the jobs except rollers. In my experience no two jobs are the same and rolling patterns can change threw out the day. It depends on the tpye of HMA, air and surface temps, material temps and other things.
Generally breakdown rolling is with a static steel roller rolling right up to the lay down machine. Then the intermediate roller sometimes a rubber tire roller is used, we use a double drum. This is where you want to bring the density up to specs, and get a smooth surface. Finish rolling is when you want to make it smoooth and get the roller marks out. You don't want to over roll at this piont or any other time either. A person should be their to establish your rolling pattern checking density with each pass for each phase of rolling. There is more to rolling black top then meets the eye, it really is an art and as with other types of equipment there is a feel to it.
Telescooper

Dwan Hall
07-07-2008, 09:51 PM
So how does a person tell if he is over rolling?

telescooper
07-08-2008, 08:36 PM
Over rolling can be identified if you see tears or cracks( this will happen sometimes if rolling in the "tender" zone with super pave{ back off **) while your rolling, or if when testing your are getting more denisty then called for. Generally you want to be around 92%-96% density. If you see factured aggs ( white streaks) you are using to much force with your vib or the material isn't thick enough.

hardhatman
02-15-2010, 09:42 PM
On some states like Maine,the rolling patterns are the following,either vibratory or static steel wheel rollers for breakdown rolling,pneumatic(rubber tired) roller for intermediate rollers and either vibratory or static steel wheel rollers for finish rolling.For example,Hypac C766D vibratory roller or Hypac C350D static steel wheel for breakdown rolling,Hypac C560H pneumatic roller for intermediate rolling and Hypac C778D vibratory roller or Hypac C350D static steel wheel roller for finish rolling.

hardhatman
02-15-2010, 09:48 PM
If a paving operation is in tandem,in some cases they use two breakdown rollers.