ASPHALT ANSWERS
Proper application of asphalt emulsion is
essential to a successful asphalt job
The Unsung HERO
of the Paving Job
TONY WIGHT
T
ack tanks are typically the most
overlooked machine on the paving
fleet. While not every paving
job requires using tack, best
practices demand that tack be used
when appropriate. For many commercial
applications, a large distributor
truck is not practical and a “pour bucket”
is not effective. Oftentimes, their
correct use is not fully understood as I
quite often get asked what can I put in
a tack tank.
Let’s first look at the different types
of material used in our industry. They
are tack (emulsion), AC (cutback),
crack fillers (rubberized material) or
sealcoat (driveway sealer). All of these
products have a use but are used in different
ways and applied with different
techniques.
Tack or emulsion is nothing more
than water and tar mixed together
using a chemical called an emulsifier.
(You thought water and oil never
mixed, right?). Emulsion is used as
a glue to help new asphalt adhere to
old asphalt. Water is a way to thin the
material and help it flow better. Most
emulsions can be applied (mostly by
spraying) at a temperature of 125 to
175 degrees. No mixing is required
other than circulating through a pump
from the bottom of the tank to the top.
This helps to heat the material evenly
and to help keep the water from separating
from the oil. Once the emulsion
is sprayed the water evaporates
(The material breaks is the term you
will hear on the job.) it leaves just the
tar to bond the two layers of asphalt.
A very important thing to remember
is AC should never be used in a tack
tank. Most of these units will not heat
over 200 degrees. Please check with the
equipment manufacturer to determine
what can be used in there unit.
AC or cutback for the most part is
used for the same thing, bonding layers
of asphalt but diesel is used to thin the
tar to make it flow. Most tanks that can
apply AC heat to a very high temperature.
Diesel burners are used as large
as 500,000 BTU’s to heat AC. Most
AC will flow at around 300 degrees.
www.callape.com [34]
1.800.210.5923