15 May 2001
 Static steel-wheel rollers. The static steel-wheel rollers consist of two-wheel
(tandem), and three-wheel (tricycle) versions. These rollers are generally used for breakdown and finish
rolling. Static steel-wheel rollers leave a smooth finish on the pavement surface, but excessive rolling
may result in lateral movement of the mixture causing surface cracking and a general loss in density.
These rollers should be equipped with a system for watering the drums and should have scrapers to
remove any material that sticks to the drums.
 Vibratory steel-wheel rollers. The vibratory steel-wheel rollers are commonly
used for compacting hot-mix asphalt mixtures. They may consist of dual-drum vibration, single-drum
vibration and single-drum static, or single-drum vibration and rubber tires on the rear axle. These rollers
can be used for breakdown, intermediate, and finish rolling. Breakdown rolling can be performed in
either static or vibratory mode. Intermediate rolling is performed in the vibratory mode while finish rolling
is performed in the static mode. The Air Force requires a maximum of 2 passes in the vibratory mode.
Although the vibratory roller is used for intermediate rolling, it does not replace a rubber-tired roller. The
vibratory roller should have a watering system on steel drums and rubber tires (if applicable) along with
scrapers on the steel drums and scrapers and pads on the rubber tires.
 Rubber-tire roller. Rubber-tired rollers are used for intermediate rolling of hot-mix
asphalt mixtures. These rollers provide for an increase in compaction after breakdown rolling and
produce a watertight surface. A large rubber-tired roller (capable of being loaded to a minimum of
2,043 kilograms, 4,500 pounds per tire and capable of minimum tire inflation pressure of 620 kPa,
90 psi) should be available for construction of heavy-duty pavements on roads or airfields. The rubber-
tired roller should have a watering system for the tires and should have scrapers and pads to prevent
accumulation of materials on tires. A large rubber-tired roller should be used for compaction of all
heavy-duty hot-mix asphalt pavements.
(b) Operation of rollers. Rollers should generally be operated at or below a rate of 4.8 to
8 kilometers per hour (3 to 5 miles per hour) (fast walking speed). Starts and stops should be gradual to
avoid damaging the freshly laid mixture. Quick turns or any turns that cause cracking on freshly laid
mixture should not be allowed.
a. Asphalt Materials. Asphalt materials used in hot-mix paving operations include the products
conforming to the specifications listed in table 2-2. The grades of asphalt specified by AASHTO MP-1
are the performance grades of asphalt developed as part of the Strategic Highway Research Program
(SHRP). This grading system is currently being implemented and, within the U.S., is the method most
often used to specify asphalt cement. The PG system has advantages over conventional grading
systems. See the information given in the section SHRP Performance grading (PG) of asphalt-cements
of this chapter.
The specific gravity of the asphalt cement shall be obtained using ASTM D 3142. This value is
sometimes required to compute a theoretical maximum specific gravity and for mixture void calculations.
The maximum theoretical specific gravity can also be determined using ASTM D 2041.
Asphalt cements for use in pavement design and construction are graded or classified in one of
three ways. They can be graded on the basis of penetration ASTM D 946, on the basis of viscosity,
ASTM D 3381; or by the performance grading system AASHTO MP-1. Currently, in the continental
United States (CONUS), performance grades of asphalt are common. However, outside the continental
United States (OCONUS), penetration grades of asphalt may be more easily obtained. When PG
binders are used, paragraphs (1), (2), and (3) on asphalt selection should be disregarded and the
procedures from AASHTO MP-1 and information given in paragraph (4) should be used for selection. In