Operate rollers appropriately
Operating procedures greatly affect the life cycle of a compactor. "Jumping curbs, driving rather than ramping the roller off the trailer, quickly moving from forward to reverse, breaking up concrete blocks, etc., can all damage the machine," says Monical. "If you use the roller the way it's designed [to be used], on jobs it's designed to do, you will positively influence how long it lasts."
Over compaction can also have negative repercussions on roller longevity. "The energy that you create in the drum has to go somewhere," Marcum points out. "If the material won't absorb it, then it comes back into the machine. That feedback, or energy, has a high potential of damaging the isolators that allow the movement of the drum. It can also cause premature damage and wear to the bearings." To minimize and/or eliminate over compaction, establish a rolling pattern for each job and verify it through testing.
Even how you secure the roller for transport can potentially affect component life. "If you over tighten the chains, you're drawing against the drum isolators and stretching and damaging them," says Marcum. "Become familiar with the machine and know when it's secure. There is no calibration or indicator, but an inexperienced driver can become too enthusiastic and tighten the chains too much."
When maintenance isn't enough
Even with an optimal maintenance program and proper operation, you may be forced at some point to make the decision between making a major repair and replacing the unit. When an existing compactor becomes more costly to repair than to purchase, or when it experiences excessive downtime, it's likely a better option to purchase new.
"And if you ever get to the point where a machine poses a significant safety problem," says Dennison, "that's another reason to upgrade to a new unit."
When determining whether to repair or replace, take into account the costs of parts, labor and downtime required to maintain or rebuild a unit nearing the end of its service life. "Certain components may be very expensive to replace, such as heavily worn drums," says Sturos. "Consider, too, that certain replacement components may no longer be readily available or available at an economical cost."
Also ask yourself if the compactor still allows you to meet job requirements in terms of size, width, tonnage and production goals. "Essentially, ask if your current roller can keep up with the paver in production," says Marcum.
With manufacturers continuing to introduce new approaches to the compaction process, you may find that the benefits in terms of mat quality and productivity quickly offset any cost advantages of repairing an existing model.
For example, new Caterpillar vibratory rollers offer an enhanced propel control system design that produces a smoother mat by providing consistent and controlled acceleration and deceleration. "The sophisticated system can also sense when the operator requires a quick stop, providing safe stoppage when needed," says Sturos.
Hamm's oscillation technology - offered on select models - is also designed to generate a smoother surface by rocking the vibratory drum back and forth, rather than bouncing it up and down. "The drum never leaves the surface of the mat. It sends a vibratory effect, but it doesn't beat it into the material," Monical explains. "The direct affect is that you rearrange the particles and achieve the final density you need, but you don't bounce up and down. You don't ever break rock over or shatter the surface. You have an ultimately flat, smooth surface with no ridge lines or bumps."
From a productivity standpoint, after correlation on the test strip, an onboard stiffness reading enables you to evaluate the effectiveness of compaction in real time without the need to wait for additional outside tests.
BOMAG's Asphalt Manager (or "intelligent compaction") is designed to yield consistent compaction quality by taking mat readings, then automatically adjusting the drum energy into the material based on the results. "With Asphalt Manager, we're checking every square foot of the site. It's not random," says Dennison. "We also have the ability to document these results, which is becoming increasingly important for jobs that require documentation."