UFC 3-270-01
15 March 2001
5.3.3. Apply the aggregate. The aggregate shall be immediately applied after binder material
application. The aggregate can be applied with tailgate spreaders on dump trucks or by self-
propelled hopper-type spreaders (Figures 5.1. and 5.2.). Spreaders should be calibrated to
ensure proper aggregate application. Aggregate that is clean, dry, and free of dust or other
undesirable material shall be used. Also, the aggregate should be hard, angular, and abrasion
resistant.
5.3.4. Roll the aggregate. The aggregate shall be immediately rolled after application. A
pneumatic-tire roller with tire pressures of 60 to 90 pounds per square inch (414 to
620 kilopascals) and appropriate size (weight) should roll the aggregate. To avoid crushing the
aggregate, a pneumatic-tire roller should be used. A steel-wheel roller can be used; however, the
weight shall be heavy enough to seat the aggregate but not crush it. The steel wheel will bridge
low spots and may not properly seat the aggregate. Rolling should continue until all aggregate
particles are properly seated.
5.3.5. Sweep the area. The treated area shall be allowed to cure for at least 24 hours before
brooming to remove loose particles (Figure 5.3.). It is better to broom during the coolest portion
of the day to prevent dislodging aggregate. Care should be taken to use only enough pressure
on the broom to remove the loose particles.
5.4. Problem Areas (SBST). All equipment shall be properly calibrated before material place-
ment. A test section can be used to ensure all equipment is in correct working order. To make
clean and straight transverse joints, it is recommended that building paper be used where the
spreading of the binder and aggregate begins and ends. After applications, the paper is removed
and a straight edge is formed (Figure 5.4.). To prevent a buildup of aggregate along the
longitudinal joint, the aggregate spread shall be stopped where the asphalt is a full thickness
(Figure 5.5.). This distance varies according to the spray width of the nozzle, but it is usually
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