LeeBoy L600 - Page 52

Temperature extremes, mixing grades of emulsion
or improper handling are the most common factors
adversely affecting asphalt emulsion. Emulsion should
never be allowed to freeze or overheat.
• Never mix different classes, types or grades of
emulsied asphalt. Even emulsions of the same grade
designation from different manufacturers can be very
different chemically and in performance.
• Warm pumps to about 150° F (65° C) to facilitate start-
up of the distributor components.
• Avoid repeated pumping and recycling since the
viscosity may drop and air may become entrained,
causing the emulsion to be unstable.
Storing Emulsified AsphaltStoring Emulsified Asphalt
A skin of asphalt can form on the surface of emulsions
when they are exposed to air. Store emulsied asphalts
in appropriate containers at 50° - 185° F (10° - 85° C),
depending upon the grade of emulsion and its intended
use, to prevent asphalt from freezing. High viscosity
rapid-set spray grades are stored at 125° F - 185° F (52°
C - 85° C).
If you want to leave the material in the distributor tank
overnight, you must be equipped with the optional
overnight electric heat system. This keeps emulsion
material at a constant temperature of 100° F (38°
C) while the distributor is not in use. It is especially
recommended that your unit be equipped with this
option if the distributor is used frequently in colder
climates.
Store emulsied asphalts at 50° - 185° F (10° - 85° C),
depending upon the grade of emulsion and its intended
use.
DO NOT heat emulsied asphalt above
185° F (85° C). Elevated temperatures evaporate
the water, increasing viscosity, and will produce an
asphalt layer in the tank that will be very difcult to
remove.
DO NOT allow emulsied asphalt
to freeze, which breaks down the emulsion and
separates the asphalt from water. This will result
in two layers in the tank that will be very difcult to
remove.
There are many types and grades of asphalt products.
Selecting liquid asphalt generally depends upon:
• Availability of various types of aggregate.
• Availability of various liquid asphalt grades.
• Climate conditions anticipated during application.
• Trafc conditions during application.
• Contract specications.
Handling Emulsified AsphaltHandling Emulsified Asphalt
It is important to select and understand the compatibility
of emulsion with the aggregate’s surface charge used
for the job and how they react with each other. The
emulsifying agent determines the charge of the asphalt
particles. This reaction to the aggregate’s surface
charge is either cationic (positive) or anionic (negative):
• Cationic emulsions work best with aggregates that
have an anionic (negative) surface charge, such as
siliceous or granite aggregates. Cationic emulsions
set more quickly in high humidity or cooler weather.
• Anionic emulsions work best with aggregates that
have a cationic (positive) electrical charge. Anionic
emulsions work well in low humidity or warm weather
conditions.
DO NOT mix liquid asphalt types,
especially cationic with anionic. Different grades
of asphalts should also never be mixed together as
this can increase the risk of re or explosion. NEVER
assume the liquid asphalt left over in the tank from
the previous job is the same asphalt needed for the
current job.
Asphalt is considered “broken” when it separates into
the components of asphalt and water. The mixture
will not ow and forms layers in the tank, usually a
watery layer on top and a gooey mess underneath.
Sometimes a crust will form on top of the mixture, a
hard dark surface with lumps in it. No amount of stirring
will recombine the mixture, so it must be removed and
disposed of properly.
Operation
L300 and L600 Tack Distributors4-8