SECTION 491
marks, visible segregation, or irregularities and in conformance with the line, grade, and cross-section shown in the Plans or as
established by the Engineer. Rollers must be in good mechanical condition, free from excessive backlash, faulty steering
mechanism, or worn parts. The empty weight and the ballasted weight shall be properly marked on each roller. The minimum
weight of static steel-drum rollers shall be 8 tons. When a vibratory roller is being used, the vibration shall stop automatically
when the roller is stopped or reversing direction of travel.
3.12.2.2 Pneumatic-tire rollers shall be self-propelled and shall be equipped with smooth tires of equal size and diameter.
The wheels shail be so spaced that one pass of a two-axle roller accomplishes one complete coverage. The wheels shall not
wobble and shall be equipped with pads that keep the tires wet. The rollers shall provide an operating weight of not Jess than
2,000 Ib per wheel. Tires shall be maintained at a uniform pressure between 55 and 90 psi with a 5 psi tolerance between al]
tires. A suitable tire pressure gauge shall be readily available.
3.12.2.3 Unless otherwise directed, rolling shall begin at the sides and proceed longitudinally parallel to the roadway center
line, gradually progressing to the crown of the roadway. The overlap shall be one-half the roller width for wheeled rollers and 6
in for vibrating rollers. No overlap is required for pneumatic-tired rollers. When paving in echelon or abutting a previously
placed lane, the longitudinal joint shali be rolled first followed by the regular rolling procedure. On superelevated curves, the
rolling shall begin at the low side and progress to the high side by overlapping of longitudinal passes parallel to the centerline.
3.12.2.4 Rollers shall move at a slow but uniform speed with the drive roll or drive wheels nearest the paver, except on steep
grades. Static and pneumatic-tired rollers shall not operate at speeds in excess of 6 mph. All courses shall be rolled until all roller
marks are eliminated.
Cores shall be collected by the Contractor at locations as determined and witnessed by the Engineer. One core per Jane mile,
but no less than two, shall be taken for each roadway segment paved. When shoulders are overlayed, cores shall be collected
solely for density information at a frequency of one core for every 750 tons of mix.
The Contractor will deliver the cores to the designated testing laboratory once NHDOT chain of custody measures have been
applied.
The minimum compaction requirement shall be 91% of maximum theoretical density as determined in accordance with
AASHTO T 209. The following reductions in unit price shall apply for all tonnage placed that is represented by any core
(excluding shoulder cores) that does not meet the minimum requirement: for results below 91% but equal to or greater than 90%,
a 5% reduction will be assessed; for any results below 90%, a 10% penalty for all tonnage placed will be assessed. At the
Engineer's discretion, the Contractor may be required to remove noncompliant material below 90% (no payment will be made
for this material or its removal).
3.12.2.4.1 All cores need not be cut at the same time. The Contractor is allowed the option to collect cores through all
placed lifts at once, provided cores are collected within two working days of placing the first course. Corrective action to any
covered course is at the Contractor’s risk.
3.12.2.5 Any displacement occurring as a result of reversing the direction of a roller, or from other causes, shall be corrected
at once by the use of lutes and the addition of fresh mixture when required. Care shall be exercised in rolling so as not to displace
the line and grade of the edges of the bituminous mixture.
3.12.2.6 To prevent adhesion of the mixture to the rollers, the wheels shall be kept properly moistened with water or water
mixed with very small quantities of detergent or other approved material. Excess liquid will not be permitted. All steel rollers
shall be equipped with adjustable wheel scrapers.
3.12.2.7 Along forms, curbs, headers, and similar structures and other places not accessible to a normal full-sized roller,
sidewalk rollers weighing at least 2,000 Ib (900 kg) shall be used. Where rollers are impracticable, the mixture shall be thoroughly
compacted with heated or lightly oiled hand tamps or vibrating plate compactors.
3.12.2.8 Unless the Engineer determines that for the weight and placement conditions a lesser number will be satisfactory
to obtain the desired pavement densities, the following is the list of required compaction equipment. The output of each paver
placing wearing course (Table 1) materials shall be compacted by the use of one each of the following complement of rollers as
a minimum: a static or vibratory steel-wheel roller, a pneumatic-tired roller and a three-axle roller or a static steel-wheeled roller.
if the required density is not being obtained with the rollers supplied, the use of additional rollers of the specified type may be
ordered. Paving widths in excess of 16 ft (5 m) will require additional rollers as ordered.
3.12.3 Performance Requirements (QC/QA).
3.12.3.1 Immediately after the hot asphalt mix has been spread, struck off, and surface irregularities adjusted, it shall be
thoroughly and uniformly compacted. The completed course shall be free from ridges, ruts, humps, depressions, objectionable
marks, visible segregation, or irregularities and in conformance with the line, grade, and cross-section shown in the Plans or as
established by the Engineer. If necessary, the mix design may be altered to achieve desired results.
2016 NHDCT
Go To=9 TOC Division 1006 Division 200 Division 300 Division 400 Standard
Division 500) Division 600 Division 700 Specifications
