VIO compactors add value

Crush-and-shape of Michigan 72

In the middle of the State Road 72, near Grayling, the project included two miles of urban four-lane pavement and shoulders with concrete curbs in the city, and five miles of rural pavement and 6 ft. shoulders on both sides. The road needed rehabilitation, because the condition was pretty rough, with alligator cracking along the road. “We’re doing a crush-and-shape of Michigan 72,” said Jeff Mertz, project foreman for D.J. McQuestion & Sons, Inc. of LeRoy, Michigan, as the Michigan Department of Transportation decided to rehabilitate the existing driving surface in-place. After this, the urban section with curbs got a top layer of 7 in. of hot mix asphalt. The rural two-lane section with shoulders was covered with a 4-in.-thick layer of asphalt.

Recycling in situ in one pass

For the recycling process, the asphalt was pulverized 8 to 10 in. deep in one pass with a WIRTGEN WR 240i down into the existing gravel base. While the asphalt was pulverized, it was mixed with up to 6 percent water. This water was introduced into the milling and mixing chamber via injection bars. Finally, the grain size of the resulting material was from 1 in. down to fines. An essential prerequisite to successful cold recycling is adequate compaction after mixing the aggregates. McQuestion on Michigan 72 routinely obtained 98 percent density using the H 13i VIO with vibration and oscillation as compacting technologies. At first they compacted the surface in vibration mode for two passes. “Then we put the drum in oscillation mode and compacted for two to three passes. Doing this, we increase the density with every pass,” Mertz says. “The oscillation really pulls the reclaimed material together in a way we don’t get with conventional vibratory compaction.” Using this method, in excess of 100,000 square yards were pulverized and compacted.

HAMM‘s VIO drum brings oscillation to earthworks

For asphalt works, standard tandem rollers with oscillation come with one vibration and one oscillation drum. As soil compactors do have only one drum, HAMM developed a solution that combines both systems: the VIO drum. There is no other manufacturer worldwide offering a similar system. HAMM VIO soil compactors are capable of working either in oscillation or in vibration mode. That is ideal for earth work, as the VIO drum is able to compact in-depth with vibration and in the upper layer with oscillation. Switching between vibration and oscillation is carried out from the operator’s platform and can even be done with the roller in motion by pressing just one button.

Why HAMM oscillation compacts so fast

HAMM oscillation compaction differs from standard vibration compaction. Whereas a vibratory drum bounces up and down on the material being compacted, the oscillatory drum creates a rapidly alternating forward-backward rotary movement without the drum ever leaving the surface. It acts dynamically on the substrate all the time. In addition, the drum is always in contact with the ground. So there is a constant static load due to the weight of the machine all the time. This leads to a rapid increase in compaction and therefore to an optimized process with fewer passes.

HAMM’s VIO compaction improves the quality

HAMM’s VIO technology also improves the quality, for example the evenness. This is, because areas that have been compacted with oscillation show an excellent longitudinal flatness. It is created because the drum is in permanent contact with the ground and there is no impact producing uneven areas on the ground. All in all, this combination works and is also extremely economical. "We get density significantly faster with the VIO roller, which boosts our productivity." McQuestion's Mertz says.