Successful Compaction using
Vibratory Pneumatic Tire Roller
Hitoshi Fujita, Yukinori Tsukimoto

Introduction
It is a pavement researcher’s distress that good designed pavement
does not always show good pavement performance. There is theconstruction stage between design and performance. In anotherwords, pavement does not show good performance without good
construction them. Most important factor of good construction will
be good compaction of asphalt mixture. By decreasing 1% air void,
the performance of pavement is improved 10% .

Kneading Compaction

Tight longitudinal Joint

The contractor must pay severe attention to get the ideal density ofthe mix that is evaluated and judged as the best proportion at themix design stage. They must select the best combination of rollers
and use them with the appropriate condition
New compaction devices such as the high frequency vibratoryroller and the vibratory pneumatic tire roller have been developedin order to achieve the required level of density in a more efficient,effective, and economical manner. In this paper the outline of new
developed VPT roller and the effectiveness of VPT roller for various
type of asphalt mixture or various thickness of pavement lift aredescribed.

OUTLINE of VPT Roller

There is an interaction that takes place between pneumatic tires andcompacted materials called the “kneading effect”, which is generated by
the deformation and compression of the pneumatic tires. This kneading
action can be simulated in a testing laboratory by a gyratory compactor
compressing a cylindrical specimen while applying both shear andvertical compression force simultaneously . This compaction mode isvery effective not only in compacting asphalt mixtures, but also inachieving a smooth surface on those materials
Among the benefits derived from the use of a Vibratory Pneumatic tireroller are the dynamic, instead of static, kneading effect. Conventionalrubber tire rollers achieve compaction through a combination of wheelload and inflation pressure. As the wheel load increases with the sametire inflation pressure, the compaction effort is extended deeper into thepavement layer. As the inflation pressure increases with the same wheel
load, the compaction effort is also extended deeper into the pavementlayer.
“Dynamic Kneading Action” of the VPT roller also achieves tightlongitudinal joints without crushing the aggregate, which makes
unwanted changes to the gradation of the mix. This is a big plus forcontractors who must meet joint density requirements recently introducedby highway and airport agencies.

Super Flat Pneumatic Tire

Comparison of finished Surface

APPLICATION of VPTRoller
The VPT roller is used all over the world. The Total amount of Japan, North
America (U.S.A. and Canada) and Australia comes to more than 90 % of sales. But
the application of each district is somewhat different. In North America, the VPTroller is used to obtain higher uniform density of asphalt mixture in the case ofincentive/disincentive payment. Another unique application in North America is forthe compaction of thick lift asphalt mixture or compaction of dense asphalt
mixture to reduce the roller train. In Japan the VPT roller is used for thecompaction of special asphalt mixture like stone mastic asphalt (SMA), porous
asphalt or epoxy asphalt that are difficult to obtain high compaction ratio. In
Australia where asphalt sealing pavements are widely applied, the VPT roller isused for the compaction of thin layer like the chip seal to avoid the cracking ofaggregate and increase the bonding between asphalt and aggregate to protect
fretting of aggregates.
Of course these are the typical application, there are the example of chip seal in
Canada and thick lift in Australia also.

District of VPT Roller Sales

Comparison of cutting core
(Thick Lift)

The developed super-flat tires of the VPT roller provide uniform contactpressure. They achieve smoother finished pavement surfaces compared
to conventional rounded pneumatic tires. The comparison of finishedsurface of the VPT roller and the conventional double drum roller isshown.

Only One in the World

Compaction of Chip Seal
Australia
Result of SMA Compaction

Conclusions

Vibratory Pneumatic Tire Roller

The mechanical features of the VPT roller is described in this paper, and based on
the worldwide construction examples using the VPT roller, following conclusions
can be made.
1)The VPT roller is used for not only thick lift, but also thin lift successfully.
Furthermore it is effective to compact various types of asphalt mixture like stone
mastic or so.
2)The combination of vibratory roller in oscillatory mode in the breakdown and theVPT roller in the finish is the best option to achieve the required density andtighter surface. It will assure durable and long lasting asphalt pavements.
3) A new roller train using only two rollers, a DDV roller and a VPT roller, easily
achieved the required level of density of the asphalt mixture. This results meansthat the contractor can construct in lower operating costs using two rollers insteadof three.
4)The strong point using the VPT roller is the possibility of covering various
applications from middle size to large size Pneumatic Tire Roller. The VPT roller isequivalent to 10t, 14t, 18t, 23t, and 28t not using or using vibration. Anotherstrong point is making smoother surface because of the wide-flat tires andavoiding the cracking of the aggregates.

Source: 2017 AAPA Conference