|
Construction Resources
New Crop of Innovative Materials
Aims for Green Benefits, Durability
by Diane Greer
A new generation of construction
materials and products - ranging from water-resistant admixtures
for concrete to soy-based bonding agents for plywood - aim
to advance efficiency and performance in building efforts.
 A
new slate of innovative construction materials and products
is coming to market, most aiming to offer improved durability
and performance or environmentally friendly alternatives to
existing options.
Some of the new materials were recently introduced in New
York at Construction Innovation, a conference sponsored by
McGraw-Hill Construction that showed off products for designers,
engineers, contractors, and developers. The sampling of products
here includes ones that are in use or planned for use in the
New York-New Jersey-Connecticut region.
Water-Resistant Concrete Admixture
A new admixture promises to solve the problem of water-based
damage to concrete by making it water- and corrosion-resistant.
Concrete is naturally porous, because of a network of tiny
interconnected capillaries. When exposed to water, capillary
action wicks the liquid through concrete, which can eventually
corrode the embedded steel bars typically used for reinforcement.
As the bars rust, they can expand and crack the concrete.
Similarly, in basements, water seeps through concrete foundations,
limiting their durability and contributing to mold and mildew
growth.
Hycrete Technologies of Jersey City, N.J., has developed
an admixture that makes concrete water-resistant. The water-based
solution reacts with the calcium in cement to form a nonsoluble
fatty acid that fills the capillaries.
The nonsoluble material also binds to reinforcing bars, forming
a microscopic protective layer that prevents corrosion. The
product contains no volatile organic compounds.
Kara Homes of East Brunswick, N.J., which builds houses,
condominiums, and adult-only communities, used the Hycrete
product in foundations for 10 houses in Edison, N.J., and
plans to expand its use to another 150-house development in
New Jersey, said David Rosenberg, Hycrete's president.
"It's about time something like this comes out,"
Robert Heller, the foreman at the Edison site for ACH Concrete
of Freehold, N.J., the concrete contractor. "It finishes
nice, sets up good, and the slump is the same. Hycrete is
more time-efficient, since you can do away with the waterproofing
membranes."
The product is most useful for waterproofing purposes, Rosenberg
said.
"It eliminates the headaches of membrane design,"
he added.
Hycrete also is intended to increase the durability and lifespan
of reinforced concrete structures. The New Jersey Department
of Transportation used Hycrete in two bridges along Route
130 and a bridge on the New Jersey Turnpike, while the Connecticut
Department of Transportation is testing Hycrete in highway
barriers.
"We are replacing epoxy-coated rebar, silica fume, and
calcium nitrate, a corrosion inhibitor," Rosenberg said.
Soy-Based Adhesives for Plywood
Something old is new again.
In the past, soy-flour was used to make adhesives for plywood.
But performance problems led to the development of alternatives,
such as urea formaldehyde-based adhesives, which are widely
used in construction.
But recently, urea-formaldehyde products have been found
to be carcinogenic to humans, according to the National Cancer
Institute, leading to a new hunt for replacements. To date,
non-urea-formaldehyde alternatives, such as polyvinyl acetate
emulsions, or white glue, and isocyanates, a chemical, are
more expensive.
Now, a new soy-flour based adhesive with performance characteristics
equal to or surpassing urea-formaldehyde adhesives is on the
market. Columbia Forest Products of Portland, Ore., in conjunction
with Oregon State University in Corvallis and Hercules Inc.
of Wilmington, Del., developed a formaldehyde-free adhesive
they call Purebond for use in veneer-core hardwood products.
The product is the brainchild of Kaichang Li, an Oregon State
associate professor of wood sciences, who was researching
how mussels attach to rocks. Li discovered an amino binder
that he combined with soy flour and other materials to create
a wood adhesive.
Columbia Forest funded the development.
"Purebond hardwood plywood is quite competitively priced,"
said Tom Kawesza, vice president of sales at ML Condon Lumber
in White Plains, N.Y.
He said he is seeing the product chosen for a variety of
high-end cabinetry and woodworking projects.
Thermoplastic Foil Layering System
A foil layering system is exhibiting various potential uses
for roofing and less conventional applications that require
transparent lightweight material.
A prominent use of the product is taking place in the renovation
of the historic Lion House at the Bronx Zoo in New York. The
facility is adding a pressure-inflated Texlon Foil roofing
system developed by Foiltec North America of Cohoes, N.Y.,
to replace traditional skylights.
This system employs two to three layers of transparent plastic
sheeting, made from a thermoplastic foil called ETFE, or ethylene-tetra
fluoro ethylene. The layers of foil are each attached to aluminum
extrusions which are themselves attached to the perimeter
of the opening that the system will cover. After fastening
the foil, air is pumped in between the layers, forming air
cushions.
At the Lion House, the foil is cut to the size of the skylight
frames - essentially taking the place of the glass in the
skylight - with the aluminum extrusion attached to skylight's
frame. Once inflated, the air pressure causes the top layer
of foil to curve up and the bottom layer to curve down.
The foils can be printed with patterns to obtain a desired
level of transparency. An air-supply unit connected to the
system monitors pressure within the cushions and adds air
when required.
Systems using a third layer in the middle would get added
flexibility to direct the air pressure within the cushion
and to further regulate the level of transparency.
At the Lion House, more than half of the 8,000-sq.-ft. roof
will use the Texlon system. Half of the system will be dynamic,
with three foil levels, allowing the Wildlife Conservation
Society, which operates the zoo, to control the amount of
light entering the exhibit.
"We can eject air out of the top layer, put more air
into the bottom chamber, and move the middle foil up to the
top layer," said Edward Peck, director of design for
Foiltec.
A major reason that the zoo selected the system was because
it allows UV transmittance through the foil, a critical factor
for live animal and plant exhibits, said Sue Chin, director
of planning and design for the society.
"Animals really need UV and birds actually use it to
see," she added.
In addition, the system has insulation properties. The panel
system's r-value, a measure of a material's capacity to impede
heat flow, is close to 3.2 - significantly higher than traditional
skylights, which average an r-value of 2.
"It's a good skylight material because of its insulation
value," Chin said. "It is part of the whole green
system in the building and provides a much better way to adjust
the heat and light in the building."
Peck said that architects of the Time Warner Center built
in 2003 in Manhattan employed Texlon in an unconventional
application - to create huge sliding doors designed to screen
window-washing equipment.
The building's design originally called for glass doors,
but the weight of the glass would have required additional
framing within the truss at the top of the building.
The Texlon foil sliding doors were considerably lighter and
printed with a pattern to obscure the view of the equipment.
Low-Heat, Transparent Low-E Glass
A new solar-control low-e glass combines low heat gain with
a high level of visible light transmittance.
The Solarban 70XL glass from PPG Industries of Pittsburgh
features a light-to-solar gain ratio of 2.33, an improvement
over the industry's previous best ratings of 1.84 to 1.86.
The ratio measures glass performance, taking into account
both solar heat gain and transparency.
"It's a breakthrough and great example of energy efficiency
as a product of engineering," said Robin Reigi, president
of Robin Reigi Inc., a materials marketing and research firm
in New York.
The product will be available for delivery to jobsites in
June.
Ecofriendly, Recycled Soy Resin
Architects, drawn by the translucency and versatility of
resins, use the material in a variety of applications including
walls, doors, and panels.
Now, an environmentally friendly ecoresin, called Varia,
has hit the market. It's made from 40 percent recycled content.
Developed by 3-Form, a company based in Salt Lake City, the
product can be tailored to specific applications by combining
colors, patterns, textures, layers, and finishes to form panels.
Quantum Inc., a data storage company in New York, will use
Varia-based panels to form a 50-ft.-long by 8-ft.-high curved
wall in its fit-out of space in a Manhattan office building,
said David Mendelsohn, project manager at Kostow Greenwood,
which is architect on the project.
The aqua blue wall, which has a textured-glass appearance,
features small clear windows providing glimpses of the company's
data storage products located in a demonstration area behind
the panels.
"We liked the flexibility and the look of the material,"
Mendelsohn added.
>>
Related Sidebar
Useful Resources
|
print this page
e-mail this page
