EXPERT ADVICE
SEALCOATING ADDITIVES-
AN OVERVIEW
By Girish C Dubey
President, STAR, INC.
Understanding the Basics in their usage.
imply defined Additives are mate-
rials added to enhance the prop-
erties of a product. In this article
we will be discussing the materials
that are added to boost the performance
of sealcoatings which may be based on re-
fined tar, asphalt or any other resin. The
use of additives in sealcoating coincides
with the very inception of sealcoatings
in the 60’s. Additives based on specialty
latex/rubber polymers have been a part
of the FAA Specification since the early
1970’s. Over the last few years, there has
been a concerted momentum by materi-
als suppliers to offer a class of products
and chemicals that are designed specifi-
cally to boost the performance of seal-
coatings. The use of such products, which
are called “Additives” have enabled seal-
coating professionals to apply sealcoat-
ings even in unfavorable ambient condi-
tions and still accomplish the optimum
performance. Although it may appear
that most of the additives are supplied to
make the sealer dry fast and set faster but
that is only a part of the benefits provided
by Additives.
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 flex-
ibility, toughness, fuel & chemical resis-
tance and overall longevity. Sealcoating
mix designs which delineate proper ratios
of various components are of critical im-
portance for the optimum performance
of sealcoating systems.
Sealcoatings are mostly supplied in a
www.callape.com
concentrated form, which must be mixed
with;
• Water to obtain a workable consis-
tency.
• Sand/ aggregate to improve the skid
resistance, abrasion resistance, cover
minor surface defects and impart a uni-
form textured surface.
• Additives to improve the overall per-
formance properties.
The topic of sealcoating additives is
quite exhaustive; therefore, we will con-
fine our discussion only to those sub-
stances that are added to sealcoatings to
accomplish the following main objec-
tives:
1. Fast Drying: Even under “not-so-ideal”
drying/ weather conditions.
2. Uniform Dry Color: Under shade or
direct sun light.
3. Sand/ aggregate suspension. Sand/ag-
gregate are used in the sealcoating mix to
improve skid resistance, produce uniform
texture and fill minor surface defects. Ad-
ditives keep sand/ aggregate uniformly
suspended in the mix, thus eliminating
settling in the bottom of the tank. Ad-
ditionally, additives help distribute sand/
aggregate evenly throughout the seal-
coating and produce a uniform textured
and streak free appearance of the finished
job.
4. Performance Improvement: Sealcoat-
ings modified with properly selected ad-
ditives improve:
a.Resistance to chemicals, deicing salts,
oil, jet fuel etc.
b. Resistance to water and elements of
weather (UV etc.),
[30]
c.Toughness, Flexibility and Elonga-
tion.
5. Thickening: It may be necessary to
boost the viscosity (thicken) the mix for
suspending large amount of sand or ag-
gregates, but occasionally thickening ad-
ditives are used to build viscosity for mix
designs using excessive amounts of water.
One must have a very clear understand-
ing that excessive amount of water in the
mix design will invariably lead to poor
sealer performance.
TECHNICAL ASPECTS: The Polymer Based
Additives.
A majority of additives are formulated
with polymers and specialty chemicals.
They are commonly supplied as liquids
in water-miscible or dispersible forms.
Polymers which are the backbone of
such additives, are large chain of mole-
cules which are made up of many types
of smaller molecules of rubbers and
chemicals. The properties of the individ-
ual molecules are manifested as well as
enhanced when they are polymerized in
larger chains of molecules. The polymer
molecules though large are still too small
to be seen with the naked eye and appear
as a milky dispersion called latex or emul-
sion. There are many polymers, rubbers
and chemical emulsions that have been
formulated in several types of additives,
therefore, it becomes important to un-
derstand the basic benefits for choosing
the right additive for the job at hand. You
do not have to understand the chemistry
but be very clear as what do you want to
1.800.210.5923