Lesson 3/Learning Event 2
Learning Event 2
ROLLING HOT MIX MATERIALS
Most mixtures compact readily under rolling if spread at proper temperatures. Rolling should
start as soon as possible after the material has been spread.
Rolling of the longitudinal joint should be done immediately behind the paving operation. The
initial, or breakdown, pass with the steel roller (Figure 9) should be made as soon as it is possible
to roll the mixture without cracking the mat or having the mix pick up on the roller wheels. The
second, or intermediate rolling (9 wheel) should follow the breakdown rolling as closely as
possible and should be done while the paving mix is still hot. The finish rolling (steel wheel)
should be done while the material is still workable enough for removal of the roller marks. The
following is suggested as a guide: longitudinal joint rolling directly behind the spreader;
breakdown rolling less than 200 feet behind the spreader; second (intermediate) rolling 200 feet
and more behind the breakdown rolling; finish rolling as soon as possible behind the second
rolling.
If the specified density is not obtained during construction, subsequent traffic will further
consolidate the pavement. This will cause rutting in the wheel paths. Use steel wheel rollers
supplemented with pneumatic-tired rollers to obtain the required density.
ROLLING PROCEDURE
During rolling, the roller wheels should be kept moist with just enough water to avoid picking up
the material. Rollers should move at a slow, uniform speed with the drive roller or wheels
nearest the paver (Figure 9). Roller wheels should be kept clean at all times. The recommended
maximum speed for rolling hot asphalt is 3 miles per hour.
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