The roller kneads the asphalt gently at the surface, driving larger particles lower and bringing fine sands to the surfaces. With the fine sands at the top, the asphalt is sealed better, decreasing the chances of water getting into it when it rains.
Pneumatic rollers can be used on several different projects such as highways, large parking lots, and driveways. They are also used on chipseal projects.
“When you do chipseal, if the rocks, chips or small aggregate that you put in the oil are rolled with a steel drum roller, you will crush it and break the rock,” Wilkens says. “Rubber-tired rollers will set the rock into the oil a little bit more and the point or the edges of the rock won’t be broken by the rubber tires.”
According to Cole, 25-ton rollers are typically used on highways, while the 12.5-ton pneumatic rollers are used for chipseal applications and county or city roads.
The machines can also be used on other projects besides asphalt, Connolly says. “A lot of times, these machines will find themselves on different types of material,” he says. “Anything that is tough to move particle-wise, you will find a pneumatic.”
In fact, contractors in Texas often use the large pneumatic rollers as proof machines on dirt applications. “They just roll 50,000 pounds back and forth over the jobsite and if it doesn’t sink or deform the soil, then it is a high-quality, compacted material,” says Cole. “It’s a verification tool. And it’s relatively unique to Texas.”
Points to consider
When determining whether to add a pneumatic roller to your fleet, there are several points to consider.
“One consideration would be what asphalt mix you are using and the target density requirement,” Monical says. “It’s really a matter of what the job is and if it would require you to have a pneumatic tire roller.”
Project owners are looking for longer lasting mix designs; as a result, the mix designs are getting stiffer. As a result, compaction is more challenging to achieve, and over-rolling with a steel drum will result in breaking the aggregate. “If I have a tougher mix design and I’m having problems getting density with the double-drum vibratory roller, or I’m over compacting to get density and I’m crushing the aggregate, my solution is the pneumatic tire roller,” Connolly asserts.
While requirements of the job factor into the purchase decision, Chastain says you should also look at your competitors.
“It’s a situation many times of what is the competition doing, first off, and being able to compete with the competition on the quality of work,” he comments. “Contractors are kind of forced into the situation to be competitive. Ideally, every asphalt paving contractor would be running a pneumatic roller.” The benefits to using a pneumatic roller are there, but they aren’t always seen immediately.
Pneumatic rollers offer versatility not available with a steel drum roller. The weight of the machines and air pressure of the tires can be adjusted to meet the specific pressure desired on a particular job.
“You are either going to adjust the tire pressure and/or you are going to increase or decrease the weight of the machine,” says Cole. “Machines come standard roughly around 20,000 to 25,000 pounds. All manufacturers have the ability to add water, wet sand or steel to bring it up to that 25- to 27-ton capacity. You can adjust the weight of the machine, as well as the tire pressure.”
Central tire inflation systems can keep tire pressure equalized and allow the operator to adjust pressure on the fly. “It’s a nice feature as long as the operator knows how to use it effectively,” says Cole.
Keeping tires in top condition
Once you’ve made the investment in a pneumatic roller, it is essential to maintain the unit in top condition. There are several areas of the unit that require regular maintenance.
Regularly check tire conditions and air pressure. “By adjusting the air in the tire, you’re adjusting the ground contact pressure,” Connolly says. Therefore, the air pressure must be checked each day to ensure proper wheel load.