Massaging the Mix

Sakai America's new GW750 vibratory rubber-tired roller is perfect for tender mix Superpave applications, stiff HMA mixes and SMA. It develops a new gyratory action that combines the field-proven kneading action of a pneumatic-tired roller with the high forces generated by a vibratory. It develops an equivalent of up to 55,000 pounds of compaction effort in a fast-moving 20,500-pound package.

This new pavement integrator is especially useful for achieving thorough compaction from top to bottom of a typical HMA lift. It takes the top-down compaction of a static roller, the bottom-up compaction of a vibratory and the kneading action of a rubber-tired roller for a totally integrated compaction effort and consistent density from top to bottom of the lift.

The process has proven useful in overcoming the problem of bridging typically found with overlays of profiled pavements where the mix does not seat properly in the grooves, even under vibratory compaction of a steel drum roller. The gyratory action of the GW750 "massages" the mix into these grooves for a much-improved interlock of the new mix with the profiled surface and integrated density of the newly-combined foundation.

Super on Superpave

NAPA/FHWA recommendations for use of conventional pneumatic-tired rollers as intermediate rollers in a Superpave train generally don't work because the pneumatic roller slows up a process that requires speed to succeed.

Sakai has determined that the combination of two Sakai 4000-vpm double-drum vibratories, followed by one GW750, followed by one Sakai R2H-1 balanced three wheeler or an 84-inch-wide double-drum running static is the perfect combination for overcoming any and all tender mix problems, giving the contractor the ability to move fast and make bonuses on incentive-based projects.

The GW750 has also proven effective for moving materials fast on stiffer HMA mixes where a higher percentage of crushed aggregates break down faster under the gyratory action of the new roller. The GW750 is also excellent on SMA mix designs.

Small roller, big results

The GW750 incorporates multi-amplitude eccentric weights in both the front and rear axles. These amplitudes can be set to develop compaction efforts from 20,500 pounds (static) to 55,000 pounds right from the operator station.

Running either statically or with dynamic force, the machine is designed for balanced pli over the width of each tire at both the front and rear axles, which translates to balanced density and excellent smoothness over the rolling width of the machine.

In addition to the excellent traction capabilities of this system, the driven tires eliminate the bow wave build up and hairline cracking typical of non-driven drums or tires. Fourteen inch-wide, super flat tires provide ample coverage and overlap for a smooth surface finish.

The articulated steering system of the GW750 is designed so that the front and rear tires track precisely for even compaction and optimum smoothness over the 77-inch-wide coverage of the machine.

The system offers an outer turning radius of less than 213 inches — ideal for maneuvering around cul-de-sacs, without shoving material due to hydrostatic differential effect. In addition, the dual variable flow motors in the rear of the machine compensate for the speed differential between the outer and inner tires and further eliminate pushing and shoving of the mat.

Dual spray systems located over both the front and rear tires provide both pressurized release agent and pressurized water that will enable the operator to get on the mat quickly and stay on the mat throughout the shift. Like all Sakai spray systems, the GW750 includes ample water reservoirs, convenient back-up pumps and spray nozzles that are quick and easy to clean or replace on the job.

The GW750 is powered by a fuel-efficient 104-hp Isuzu water-cooled diesel engine with a displacement of 264 cubic inches. This engine meets Tier II emission standards. As on all Sakai rollers, ROPS and seat belts are standard.