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System performance (relative to the environment in which it is
installed) depends greatly on the chemistry and flooring type selected for the
application. Although there are a myriad of technologies used in the industrial
coating industry, the most traditional and widely available include acrylic,
epoxy, polyurethane, polyurea, polyaspartic, polyester, or vinyl ester.
CONCRETE HARDENERS OR DENSIFIERS
Concrete hardeners are usually sodium silicate, potassium
silicate, lithium silicate, solutions or metallic fluorosilicates. Where
hardeners have been used, the concrete will usually appear glossy and may be a
grey to brown color. Hardeners used instead of sealers and for new concrete as
well as existing concrete. These products typically improve with age. The
Densifier actually crystallizes in the concrete accelerated by the general
scrubbing of the floor or by concrete polishing. Over time these floors develop
a very attractive gloss and are excellent for warehouse areas where cost is the
first priority but appearance is also important.
ACRYLIC RESINS, also known as Methyl methacrylate resins and
co-polymers, are used for waterborne coatings, such latex house paint. It is also
used in adhesive formulations. Acrylics coatings - vary from extremely hard,
brittle solids to elastomeric (rubber-like) structures to viscous liquids. These
materials tend to have excellent water, weather and UV resistance. In addition,
they are stable under moderate thermal shock conditions, but provide lesser
mechanical strength, chemical resistance, and adhesion compared to alternate
systems.
 MMA (Methe Methacrylate)
MMAs are fast curing acrylic coatings that are resistant to
weak acids and alkalis and have moderate resistant to solvents. Fast curing is a
big advantage of MMAs, especially at low temperatures. At room temperature MMA
has a working time of 10 to 15 minutes and reaches a full cure in 1 to 2 hours.
MMAs are two-component systems in which the MMA resin is mixed with a solid
powder initiator. After mixing, curing of MMAs is inhibited by oxygen in the
air. Manufactures overcome this problem by including paraffin wax in the resin.
During cure, the wax rises to the surface forming a protective barrier.
When applying as a resurfacer it is important to use the continuously graded
aggregates from the manufacturer to avoid trapping air within the resurfacer.
MMAs must be applied to dry concrete because moisture interferes with binding.
MMA have excellent intercoat adhesion and are resistant to ultra-violet light.
Their maximum surface temperature is normally 140 degrees F. MMAs release a
strong odor and are flammable, so it is important to ventilate the work area.
Epoxy resins are thermosetting products known for excellent
surface and sub-surface adhesion, mechanical properties, and chemical
resistance. Epoxy resin systems are made up of an epoxy resin and a curing agent
(also called a hardener or catalyst). Many epoxy products also contain additives
such as organic solvents, fillers such as fiberglass or sand, and pigments.
When epoxy resin systems are used, single molecules (monomers)
of the epoxy resin chemical and the curing agent combine to form long chains of
molecules (polymers). As the mixture "cures," it becomes a hard polymer. Some
epoxies cure in a few minutes at room temperature. Other epoxy systems need
additional time or heat to harden. The characteristics of hardened epoxies (such
as whether they are firm or flexible, or resistant to heat or chemicals) depend
on which epoxy monomers, curing agents, solvents, and fillers are added.
There are two primary epoxy resins A epoxy resin which is a
cost-effective, general-purpose resin which demonstrates excellent alkali
resistance, good acid resistance and fair-to-good solvent resistance.
BISPHENOL F epoxy resin is a low-viscosity material which provides excellent
alkali resistance and offers improved acid and solvent resistance compared to
BISPHENOL A.
While there are few epoxy resins that are suitable for
application, there are literally hundreds of epoxy curing agents. As a result,
epoxies can be formulated to have a variety of physical properties, which makes
it difficult to generalize their chemical resistance as a polymer coating. Cure
rate of epoxies is affected by temperature and should not be applied with
temperatures under 32 degrees. Epoxies have limited service temperatures and
generally soften with temperatures over 150 degrees. They are also not resistant
to ultraviolet light and will yellow with age.
The hardened, finished polymers are almost non-toxic; it is
exposure to the uncured resin components that can be harmful. In a two-component
epoxy product, the epoxy resin and the curing agent are packaged separately and
must be mixed together just before being used. Each component can be hazardous.
In a single-component product, the resin and the curing agent are supplied in a
pre-mixed form.
 Epoxy Formulations
Epoxy for concrete coatings generally come in one of three
formulations. Solvent based, water based, and 100% solids. Solvent based and
water based tend to be most commonly used for DIY applications due to their ease
of application and long curing window after catalyzation. 100% solids
formulations while more difficult to apply are more cost effective when
comparing cured thickness and can be applied at much greater thicknesses
allowing the material to self level.
100% solids epoxies are the most popular form of epoxy. The
percent solids describe the amount of solvent in the product. In this case there
is no solvents or liquid fillers of any kind. As a result these epoxies offer
odorless installation. They cure exclusively by chemical catalyzation between
the parts. What is surprising for some is that 100% solids epoxy are normally
97% plus solids but typically have the addition of bonding additive, leveling
agents or other additives to aid application. As a result not all epoxies are
equal.
Solvent Based Epoxies can vary significantly from one another.
What holds them together is there use of solvents to aid in application,
adhesion and/or leveling properties. They normally range from 30-70% solids are
easier to apply than 100% solids epoxy and due to their solid content are much
thinner after the solvent has evaporated and they have cured. Solvent based
epoxies are generally more tolerant of petroleum based surface contaminants such
as oil.
Water Based Epoxies are much the same as solvent based epoxy.
There major difference is the use of water as the carrier rather than a solvent.
With the increase government regulation and the harmful odors of solvent based
epoxies these are much more popular. They are however a little more expensive
than solvent based due to the technologies and can be a little more fickle for
installation.
Specialized Epoxies
Flexible Epoxies are modified to provide elongation in
addition to epoxies normal properties. Like Polyurea they can be used for joints
and areas susceptible to movement like exterior slabs and multi story structures
parking ramps.
NOVOLAC EPOXY - is fast curing and offers excellent protection
for secondary containment where resistance to strong alkalis, acids, and
solvents are required. Novalac epoxies have many properties of conventional 100%
solids epoxy. Their difference lies in their polymeric structure. In chemical
terms, novalacs have a higher cross-linked density than conventional epoxies.
This makes them more rigid and chemical resistant, and allows them to withstand
higher service temperatures. These properties lend themselves for use in
chemical containment and battery charging areas. The downside to their higher
cross-linked density is that novalacs are typically more viscous than
conventional epoxies, which make them more difficult to apply.
Polyurethane resins, commonly referred to as urethane, are
thermosetting or thermoplastic and demonstrate moderate chemical resistance and
good resistance to diluted acids and alkali. Polyurethane resins generally offer
moderate adhesion, but good resistance to shrinkage and good flexibility.
Urethanes are a popular high-performance floor coating. They have many desirable
properties, including fast cure times, high abrasion resistance and toughness,
and good chemical resistance. They are typically the most resistant to water
exposure, high humidity, temperature extremes, and fungus or mildew. Urethanes
performed best when placed on dry concrete. Moisture inhibits the cure of
two-component systems and can cause blistering of moisture-cured coatings
because of its reaction with water generate carbon dioxide gas.
The first essential component of a polyurethane polymer is the
isocyanate. Isocyanates can be classed as aromatic, or aliphatic. Important
characteristics of isocyanates are their molecular backbone, solvent content,
functionality, and viscosity.
Moisture cured Urethane
The “old stand-by” of urethanes are aromatic urethane also
described as moisture cured urethane. Most commonly installed on wood floors,
these urethanes are normally single components and dry through reaction with the
moisture or humidity in the air. They can vary from 20% to 70% in solids with
the remainder evaporating. As a result this percentage determines the dry film
thickness once the solvent has evaporated. Still a good product for some
applications its biggest drawback is its tendency to yellow over time due to low
UV resistance and offensive solvent smell during application. Moisture cured
urethanes are widely used because they perform well and offer the convenience of
a one-component system but in aliphatic urethanes generally provide better
performance.
Aliphatic Urethane
Aliphatic Urethane is the next step urethane resin technology.
It is still likely solvent based and a two component product much higher in
percent solids. The primary performance difference between moisture cured
urethanes and Aliphatic Urethanes is due to its chemical resistance being
significantly higher. These products can resist solvents including methylene
chloride (the active ingredient in paint stripper). The main reason that
aliphatic isocyanates are used in making polyurethane coatings is the two-part
product it is also UV stable holding its color with time.
Odorless Urethanes
Next generation or as they are commonly described “Odorless”
Urethanes have come about as a result of the restrictions on solvent use in
manufacturing facilities as well as government influence. There are numerous
formulations that vary greatly in performance as well as cost. The difficulty is
determining the quality. The main formulation techniques used to achieve
odorless urethane is the use of water instead of aromatic solvents and the
development of very high to 100% solids urethane products (80 to 100% solids).
The increased desires for odorless polyurethanes have also led to the
development of the sub group of urethanes known as Polyureas and Polyaspartics.
Urethane Mortar
Developed roughly 30 years ago urethane mortars have increased
in popularity from the original BASF’s “Ucrete” to more than a dozen major
manufacturers producing them currently including Sherwin Williams, General
Polymers, Tennant, Crawford Laboratories, Garland and Rustoleum. Urethane
mortars combine cement with water based urethane technology to produce a mortar
product exhibiting properties of both.
Continued development over the past 15 years has in these
systems with increasing high resin content and low viscosity. Designed to
exhibit a high cross-linked density, cementitious urethane systems are
non-toxic, non-hazardous, and highly chemical resistant and further developments
allow for more effective and efficient installation.
Because of low temperatures during installation urethane
mortar flooring is ideal for food processing and pharmaceutical manufacturing
facilities. Floors in these environments are subjected to abuse, heavy traffic,
chemical attack, extreme temperatures resulting in extremely hostile conditions.
Urethane mortars do well in these abusive environments but may not be required
in every plant area. Epoxy mortar systems, due mostly in part due to cost, are
still the preferred material for less demanding environments.
The advantages of applying a urethane mortar flooring system
are numerous. The cementitious urethane composition has a similar modulus of
elasticity to that of concrete. This all but eliminates differential flexing
that is prevalent with most other resins.
In addition to being able to absorb and withstand extreme heat
and cold temperature change, urethane mortar systems also have sound deadening
properties. These are particularly useful in areas exposed to steel wheel
traffic such as bakeries. Urethane mortars can also effectively withstand abuse
from impact such as dropping of objects such as pots and pans found in
commercial kitchens.
Another advantage of urethane mortars is that typically do not
require a primers saving considerable installation time. Primers for urethane
mortars do allow for installation over dairy brick and tile eliminating the need
for removal of existing flooring while eliminating the need for regular
maintenance of grout joints.
In the case of new concrete the unique chemical composition of urethane mortars
with their similarities to concrete allow for installation over freshly poured
concrete, thus eliminating the need for the typical 28-day wait time for the
concrete to cure.
While there are numerous advantages to urethane mortar
flooring systems, there are several disadvantages too. Having a cement and water
cure, installation of these systems should be avoided at temperatures over 90
degrees F to reduce the risk of blistering from increased carbon dioxide being
trapped during the rapid initial curing process. Due to their rapid cure time
the installation of a urethane mortar system their primary purpose is for
performance where as epoxy floor systems tend to allow for more decorative
installations.
Urethane mortars are available in three primary forms a trowel
applied mortar, a self-leveling slurry and a self-leveling slurry that can also
be broadcast into for an aggressive anti-slip texture and/or a decorative quartz
or ceramic carpet finish. All of thise installations typically range in
thickness from ¼ inch to 3/8 inch with some newer products that can be applied
as thin as 1/8 of an inch.
Polyurea
Polyurea is a subset of Polyurethane when isocyanates react
with water to form a urea linkage and carbon dioxide gas; they also react with
polyetheramines to form polyureas.
Polyurea applications include joint sealant technology.
coatings and linings are most commonly seen applied over truck bed liners for
corrosion protection and abrasion resistance. They also have tremendous
advantages over conventional materials for joint fill and caulk applications due
to their fast set nature, high elongation typically in excess of 300% and
durability/abrasion characteristics. Polyurea comes in three primary
formulations spray, caulk grade (packaged in dual component cartridges with
special mix tips, and hand mix formulations.
Due to
polyureas extremely fast cure nature (usually in less than a few seconds)
specialized application equipment is often needed for installation. Polyureas
are generally odorless with 0 VOC’s, extremely flexible and when sprayed due to
lack of solvents allow for almost unlimited thickness in a single application.
Polyaspartic
Polyaspartic is a type of polyurea (actually a polyaspartic
aliphatic polyurea). All polyureas are two-part systems, meaning that a resin
has to be mixed with a catalyst to create the curing reaction that hardens the
material. Polyurea has been used very successfully for corrosion-resistant
coatings and repair materials, although application is awkward since it has an
extremely short pot life—about 3 seconds, so the two parts must be mixed at the
spray tip, requiring lots of maintenance on expensive high-pressure equipment.
Polyaspartic polyurea (or simply polyaspartics) overcomes many
of those difficulties, while retaining the advantages by combining the best
properties of polyurea and Aliphatic Urethane technology. According to Bayer
Material Science, polyaspartics are "based on the reaction of an aliphatic
polyisocyanate and a polyaspartic ester, which is an aliphatic diamine."
For most of us, the important thing to understand is that
polyaspartics are a polymer coating material that has a rapid cure time for 5 to
120 minutes depending on formulation, can be applied to surfaces with extreme
temperatures from -30°F to 140°F. Polyaspartics generally have very low
viscosity, equivalent to water, which gives it outstanding wetting ability to
apply a high build in one coat, UV stability, and excellent chemical and
abrasion resistance thus providing some of the best properties of epoxy resins
and urethane resin technology.
The main drawback, cost. Polyaspartic resins tend to be 3 to
10 times more expensive than 100% solids epoxy resins.
SPECIALTY
PRODUCTS
Polyesters
Polyesters are two-component systems in which a pre-polymer
resin dissolved in styrene is mixed with a peroxide catalyst. Polyesters are
fast setting, high strength, and demonstrate excellent resistance to acids and
most solvents, but they are generally susceptible to alkali attack. Polyester
resins experience a relatively high amount of shrinkage. Styrene flammability
and fumes must be considered when using this product. Polyesters resins are most
commonly used for chemical containment both primary and secondary in areas
exposed to aggressive acids.
Vinyl Esters
Vinyl Esters are a type or subset of polyester resin, in which
the pre-polymers are formed by reaction of epoxy resin with acrylic of
methacrylic acid. Vinyl ester resins provide ultimate performance in chemical /
corrosion resistance. The products are typically formulated in high build, fast
curing systems for corrosion resistance and toughness. Again, styrene
flammability and fumes must be considered.
Oil Primers
Oil Primers are designed specifically for old concrete that
has been consistently exposed to oil. It is still a good idea to remove any
surface oil as it can become acidic and wear away at the concrete however they
can incorporate oil into their binding matrix and provide good adhesion to an
otherwise un-adhere able surface.
Moisture Tolerant Primers
Moisture tolerant primers these products many of which are
water-based epoxies provide a primer that can adhere to wet or damp concrete.
Some moisture tolerant primers allow for application to “green concrete” or
concrete less than 28 days old as well as creating a breathable surface where
water vapor can travel up through it but still creates a waterproof surface.
Pre-Primers / Tack Coats
Pre-Primers are generally high solvent products that both
clean and prime difficult to adhere to surfaces such as ceramic tile, quarry
tile, dairy brick, and even glass allowing for the application of various resin
systems as topcoats.
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Vanguard Concrete Coating
3030 Hillcroft SW
Grand Rapids, Michigan 49548
Phone: 616-742-1540
Fax: 616-742-3793
Ian@vanguardconcretecoating.com
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rights reserved by Vanguard Concrete Coating of Grand Rapids, MI. For residential floors our service area
includes the Central, Southwest, & West
Michigan cities of Grand Rapids, Muskegon, Traverse City, Mount Pleasant, Midland, Bay City, Saginaw, Flint, Howell, Jackson, Lansing, Kalamazoo, South
Haven, Holland, Grand Haven and small cites in-between. For industrial &
commercial clients we service a larger area including Detroit & Ann Arbor, Ohio / OH,
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