EXPERT ADVICE
for easier mixing.”
There are primarily three types of
pavement sealers. They are commonly
known as refined tar-based (coal tar
based), asphalt-based, and petroleum-based.
All three have their advantages
but are typically chosen by the
contractors’ preference unless otherwise
specified.
“Additives are a very important tool
for the contractor to have in their
toolbox,” said Shannon Hemsink,
development director with Neyra Industries,
Cincinnati, Ohio. “Additives
are formulated products produced by
the sealer manufacturer to enhance the
characteristics of the pavement sealer.
They are typically composed of latex
polymers and other materials.”
Hemsink added: “It is good to use
additives when temperatures are below
60 degrees Fahrenheit and when temperatures
are above 90 degrees Fahrenheit.
In both temperature extremes,
the additive can help with proper film
coalescence to ensure a durable, long
lasting sealcoat.”
Sealcoat additives are also said to
help in conditions when there is less
than 24 hours of cure time, when
weather conditions are less than ideal
within 48 hours of application and
when application is made late in the
day or at night.
“As with anything, additives do have
limitations,” Wellman said. “They are
never a cure-all if your surface is in
really bad shape--some failures are still
going to happen. Also, you can put too
much additive in your mix which, in
my experience, can actually give you
the complete opposite result, such as
slowing the cure time of your sealcoat.
It’s always important to talk to your
supplier and get the recommended mix
ratios for your application to ensure
best results.”
Clearly there are benefits to sealcoat
additives. Additives do add to the
performance of the pavement being
protected.
Some additives act like a drying
agent to accelerate the drying and cure
time of the sealcoat. “Dry” is when the
sealcoat doesn’t transfer to the touch,
and “cure” is when all the moisture
has been driven out of the sealcoat and
it is fully set (adhesive and cohesive
strength reaches its strongest point,
and the film cannot be re-dissolved in
water).
“Considering the myriad of additives
available today, it is crucial to understand
the basic chemistries and select
the ones that will truly enhance the
performance of the sealcoating in terms
of better flexibility, toughness, fuel/
chemical resistance and overall longevity,”
stated Dubey.
Dubey described a handful of performance
objectives for additives:
1. Fast Drying: Even under “not-soideal”
weather conditions.
2. Uniform Dry Color: Under shade
or direct sun light.
3. Sand/aggregate suspension: Sand/
aggregate are used in the sealcoating
mix to improve skid resistance,
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