Train Operators to Reverse Right
BY John Ball
Getting proper compaction on the project is the key to a long-lasting asphalt pavement. While you probably won’t put a brand-new worker on the breakdown roller and expect everything to go well, cross-training employees is vital to a crew’s success. You want to teach all members of the compaction train the best practices of rolling for a bonus-worthy mat. Reversing is a skill to spend some time on.
Let’s use the image on this page for reference.
This picture shows an excellent roller operator using best practices on a second pass with the breakdown roller. I want to call your attention to her position in the cab, seated so she can see well moving in both forward and reverse.
But look at the position of the roller itself. You can see that she’s rolled toward the paver, coming onto the hottest part of the mat at an angle. She’s turned gently as she’s come to a stop for reversing. While you can’t see it in this picture, I can tell you she has also turned off the vibe as she’s slowed to a stop so she’s not pounding the mat and breaking the aggregate in the lift. This is the proper way to roll a pass.
Let’s break it down.
As you roll toward the paver, watch your intelligent compaction (IC) screen to see what temperature the mat is. While the water on your drum is not a problem as you’re rolling toward the hottest part of the mat, squeezing the bow of material and water under the hot drum, it could present a problem as you reverse and roll away from a mat that’s 300-degrees or higher. The boiling water, bubbling up as you roll away, can cause a ribboning effect on the new mat in an extremely hot area. Watch your temperatures and adhere to the rolling patterns your quality control team has set for the mix you’re working with.
While you will roll in a straight line toward the paver, you will turn gently to curve away from the straight line before coming to a stop. You don’t want to shove the mat with a hard stop that’s parallel to the screed. You don’t want to create a dip in the mat where the roller drum has stopped and settled before reversing.
When going into the slight and gentle turn, turn off the vibration to prevent overcompacting while slowed, stopped and reversing. You can turn the vibe back on as you get back up to speed.
This maneuver isn’t as important on the cold section of the mat, but the operator should still try to slow to a gentle, angled stop at the back end of the pass as well. She should definitely turn off the vibe when stopping to prepare for the third pass toward the paver.
As always, don’t let roller operators stop for any length of time on the hot part of the mat. If an operator must stop to wait on the paver or to refill a water tank, make sure this pause happens beside the paved lane or on the coolest part of the mat and on an angle that can be easily rolled out.
For other rolling back-to-basics best practices, check out the online course I put together with AsphaltPro Magazine at training.theasphaltpro.com/ or give me a call for one-on-one training with your crew in the field.
John Ball is the proprietor of Top Quality Paving & Training, Manchester, New Hampshire. He provides personal, on-site paving consulting services around the United States and into Canada. For more information, contact him at (603) 493-1458 or tqpaving@yahoo.com.