Floor Sealer on Steroids
Novel Green Sealer Technology for Decorative Concrete Flooring
By Steven Reinstadtler
Bayer MaterialScience LLC
Presented at the recent Polyurethanes 2011
Technical Conference hosted by the American Chemistry Council, this paper discusses
the use of two-component ultra-low-VOC
waterborne polyurethane sealers that can be
used in conjunction with decorative concrete options to achieve both durability and
aesthetic targets.
Arecent trend, especially in sustain- able building practices, is the use of a building’s existing concrete
floor as a decorative element of the structure. Architects and designers are increasingly using this ubiquitous building
component in more and more aesthetically pleasing ways. Diamond polishing,
stamped concrete and decorative stains
are being employed as durable yet beautiful floor options in both new construction
as well as refurbishment work. However,
these concrete surfaces and finishes can
still lose their appeal should the wrong
liquid accidentally come in contact with
the surface since current sealers may not
resist many common staining agents. The
use of two-component ultra-low-VOC
waterborne polyurethane sealers can be
used in conjunction with decorative concrete options to achieve both durability
and aesthetic targets.
Introduction
For the use of concrete as a decorative el-
ement in commercial buildings such as re-
tail space, large grocery chains, office
buildings, and light industrial structures,
there are several types of concrete flooring
options that may be used. First, an exist-
ing concrete floor may be ground and pol-
ished to a high gloss using diamond
grinding equipment. Typically, the final
polishing grit varies between 800-3000
grit. This method works well when the ex-
isting concrete floor is in good shape, has
desirable aggregate content, size, and color,
and is free of major cracks. After polish-
ing, the floor may also be treated with a
lithium silicate-based densifier, which cre-
ates a harder surface that resists micro
abrasion and the subsequent concrete dust
that can be generated. Additionally or sep-
arately, the concrete can be treated with a
decorative stain, which imparts a desired
color and look to its natural plain finish.
By itself, this floor preparation method ini-
tially allows for a durable finish and good
aesthetic qualities. However, over time the
surface may be exposed to chemicals and
foodstuffs, which can stain or even dam-
age the concrete creating an uneven spotty
look. Even with the use of a densifier, the
concrete surface can remain porous
enough for certain staining agents to pen-
etrate and discolor it in places. In grocery
stores, some common products can signifi-
cantly alter the appearance of decorative
or polished concrete if they are acciden-
tally spilled on the floor. For instance, vine-
gar, pickles and relish will etch the
concrete due to their acetic acid content
and cause a discolored area, as well as a
down-glossing of the affected area.
Recent developments of waterborne
polyurethane coatings and sealers address
many of the desired attributes sought by
the formulator, contractor, and owner
such as:
- Chemical and Stain Resistance
- Ease of Use
- Low Odor
- Concrete Penetration
- Long Term Performance
By drawing on the proven power of
polyurethane chemistry in many adjacent
markets1, novel two-component waterborne
polyurethane technologies have been devel-
oped that meet or exceed the desired targets
of this growing market segment. For
decades, solventborne polyurethane coat-
ings have been considered the mainstay for
high performance coatings used in architec-
tural, industrial maintenance, corrosion, and
construction applications due to their excel-
lent mechanical and weathering properties.
But increased governmental, regulatory, and
sustainability pressures have created a need
for coatings technology that would reduce
or eliminate VOC, HAPS, heavy metals
and/or other environmentally detrimental
compounds. In the past decade, the first gen-
eration of waterborne polyurethane coat-
ings was formulated and introduced to the
market. While offering the chance to replace
some of the VOC and solvents with water,
many of these coatings still had in excess of
250 g/L of co-solvent. In addition, these
coatings often fell significantly short of the
solventborne polyurethane standard in
chemical, abrasion and UV resistance. As
with most emerging technologies, the learn-
ing curve was steep and the second genera-
tion of waterborne polyurethane coatings
was developed with the goal of meeting or
exceeding the desired traits of the solvent-
borne polyurethane coatings but with sig-