Some asphalt contractors follow up compaction by steel drum rollers with pneumatic rollers. For a given job’s conditions and type of asphalt mix, the use of pneumatic-tired rollers can result in a smoother, longer-lasting surface. Therefore, they are mainly used in finishing work, after steel drums have completed the initial compaction phase.
As implied by their name, pneumatic rollers use air-filled rubber tires instead of steel drums. Rather than distribute the machine’s overall weight across a single horizontal line, each tire is a point of contact, increasing density and uniformity of compaction with a kneading action that drives larger aggregate downward in the course, allowing finer grains to rise on top. The positions of the tires in the rear row are staggered relative to those in the front row to ensure even coverage.
Tire pressure is automatically controlled at a designated, uniform psi to alter their effect. Designated pressures range most often from 60 psi to 120 psi.
Since hot asphalt sticks to cold rubber, causing tears and imperfections in the mat, the tires are generally not permitted to cool down while in use. Many pneumatic tired rollers feature insulating mats that hang to the ground from the roller’s frame, to prevent the tires from cooling.