s1 Concrete Cvr - Specify Concrete

Transcription

september 2005
Sponsored by
Brems family house photo courtesy of NCMA. See page s12.
A Special Section in:
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2005
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BUILDING GREEN WITH GREY CONCRETE
innovation and classic approaches drive today’s sustainable design
by jennifer g. prokopy
als for its raw materials. Concrete also offers thermal mass, lowers
urban heat island effects, is recyclable, uses local materials, creates
energy-efficient structures, is economical and highly versatile, and
comes in tons of textures and colors.”
Frentress argues that in many cases, concrete can minimize the
material requirements of a structure. Minimizing or eliminating
unnecessary components or processes is often an easy solution.
This kind of thinking, says David Shepherd, director of sustainable
development for PCA, is what the industry needs most. There are
many innovations in concrete, but even more important: “There are
often simpler ways of doing things. There are methods that have been
working well for decades.”
CATCHING UP: CONCRETE BUILDS GREEN HOMES
Water flows through a demonstration sample of pervious concrete pavement. Photo
courtesy of the California Nevada Cement Promotion Council.
E
Everywhere you look today, there are concrete innovations. New concrete mix designs create sleeker, stronger structures that achieve
amazing energy efficiency. Manufacturing refinements reduce pollution and energy use. Manufacturing and construction processes use
more recycled materials—both in volume and variety. And architects,
engineers, and contractors are enhancing time-tested methods that
have always been sustainable.
The Portland Cement Association (PCA) consulted industry
experts with diverse experience to look at what’s happening today in
manufacturing, design, construction and building performance. Some
of the hottest trends are the growth of green building in concrete
homes, the use of pervious concrete pavements for water conservation, and the continuing drive to achieve unique, optimal concrete mix
designs using supplementary cementitious materials.
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NEW DIRECTIONS IN THE INDUSTRY
s4
With sustainable building practices rapidly becoming a common consideration, the concrete industry has shifted its thinking, putting
more emphasis on educating the building community on the techniques and benefits of using concrete and other cement-based products. Dave Frentress, marketing director for cement and ready-mixed
concrete manufacturer Glacier North West, has made it his mission to
spread the word about concrete. He recently was named Promoter of
the Year by the National Ready Mixed Concrete Association.
“In this age of vanishing resources, we must choose our building
materials wisely, balancing the expenditure of natural resources with
the benefits of a material over its useful life,” says Frentress. “Concrete
draws upon some of the earth’s most common and abundant materi-
Awareness of sustainable design in homebuilding is on the rise,
according to Shepherd. “What we’re seeing in the residential market
today is what was happening three or four years ago in commercial
building,” he says.
Eric Fulton, communications manager for the Building Systems
Councils of the National Association of Home Builders (NAHB), says
that approximately 16 percent of new homes use some sort of abovegrade concrete wall system. This is, in part, why NAHB established its
Concrete Home Building Council: “A lot of builders may not realize the
capabilities and properties of concrete and cement-based products,
and their contribution to green building,” he explains.
Concrete’s homerun for any residential application is its energy performance, says Shepherd. “Houses are relatively simple. You can use a
concrete from the ground up
cement manufacturing:
• limestone, the predominant raw ingredient of cement, is the most
abundant mineral on earth
• while cement manufacturing requires high energy, cement is only a
small portion of concrete (10 percent to 15 percent)
• industrial byproducts can be used to fire kilns or as raw materials
where cement is manufactured, instead of being landfilled
construction:
• concrete is ordered and mixed for each job, minimizing waste
• leftover concrete can be recycled
• materials are derived and manufactured locally, minimizing
transportation
• industrial byproducts like slag cement and fly ash can be used in
concrete as supplementary cementitious materials
building operation:
• thermal mass increases energy efficiency, reduces temperature swings,
and increases comfort
• high reflectivity reduces urban heat island effect
• durability means concrete structures outlast many others and
typically require less maintenance
• virtually inert, concrete improves indoor air quality
demolition:
• almost all concrete can be crushed and recycled, for road building
or as aggregate for new concrete
concrete
Comprehensive
Green- and rose-colored pervious pavement sidewalks were used in Guadalupe Dunes County Park in California’s Santa
Barbara County. The park is located just above the high tide line on the Pacific Ocean. Photo courtesy of the California
Nevada Cement Promotion Council.
for Homes. Jim Hackler, program manager,
says the program was launched Aug. 3, 2005,
in 11 markets across the country. While it
does not call out specific products, says
Hackler, “the core of the program is examining energy. Certainly, in a concrete home,
performance levels will be incredible.” The
program will also offer innovation points,
which concrete systems may be able to
achieve. “It shouldn’t be about fighting
point-for-point,” adds Hackler. “It’s about
practices that make sense for a specific home
and a specific home buyer.”
SAVING WATER WITH PERVIOUS
CONCRETE PAVEMENTS
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environmental design + construction
One concrete technology currently gaining
attention across the nation is pervious concrete pavement. Made with the same ingredients as conventional concrete, without fine
aggregates, the material is primarily used for
parking lots. This simple mix creates a concrete with large voids, allowing water to pass
through the concrete and into the ground.
“Pervious concrete acts in an environmentally friendly way,” says Don Wade, marketer
for Missouri-based Magruder Construction.
The firm is constructing pervious pavements
all over the U.S., says Wade, because its benefits serve almost any community. “It allows
rainfall to pass through to the ground underneath, minimizing or eliminating stormwater runoff. Pollutants are captured, water is
retained and purified, recharging the
aquifer,” he explains. He adds that every state
currently has programs testing the viability
of the material.
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september 2005
high-performance wall or roof system and
make a huge difference in how your house
impacts the environment, over decades or
even a century.”
In addition to wall systems, concrete can
contribute to home building in many other
ways. Concrete creates long-lasting driveways and sidewalks. Made with pervious
concrete pavement, they can reduce
stormwater runoff, as can decorative concrete pavers, which create safe, ecologically
friendly patios and decks. Concrete floors are
decorative, functional, and durable, as are
concrete roof systems and fiber-cement siding. Concrete countertops are a cost-effective
alternative to expensive stone finishes. And
with limitless color and texture options, all
of these components can be specified to
achieve a fabulous aesthetic.
NAHB also recently released voluntary
Model Green Home Building Guidelines (at
www.nahb.org/gbg). John Loyer, construction, codes and standards specialist in NAHB’s
Energy and Green Building Department, says
the guidelines grew out of member interest.
“We created a document that delineates, for
the mainstream homebuilder, how to ‘green
up’ building practices—or for a builders’ association to start a green building program,” says
Loyer. The guidelines, representing the expertise of more than 100 organizations, will be
updated every two to three years to incorporate cutting-edge technologies.
The U.S. Green Building Council, creator
of the Leadership in Energy and Environmental Design (LEED®) Green Building Rating System, is also in the game with LEED
s5
concrete
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s6
The City of Encinitas, Calif., used pervious pavement for sidewalks, parking lots
and the park’s entry area. While the parking lots are gray, sidewalks (like those in
this image) are colored red and buff. Photo courtesy of the California Nevada
Cement Promotion Council.
Environmentalists have for years pointed
to parking lots as a source of pollution for
lakes and rivers, but pervious pavement can
stop that process. Andrew Marks, managing
director of the Puget Sound Concrete Specification Council, says that in his region (in
the state of Washington), its key benefit is
wildlife protection. “We have a heavy emphasis on protecting the water for salmon propagation,” he says. “All the streams in this area
feed into the Puget Sound, and salmon
stocks have depleted over the years.”
David Akers, senior engineer for the California Nevada Cement Promotion Council,
says stormwater maintenance is a key selling
point in the southwest. Pervious pavements
are being used all over the region to conserve
water in ballparks, parking lots, sidewalks,
hardscaping, and more.
Pervious pavements can also save space and
money, says Marks. In property development,
the impervious surface area will determine the
space set aside for stormwater retention
ponds, as well as pipes and other structures.
Pervious pavement can minimize or eliminate
the need for retention ponds and other structures. That increases the land area available for
use, which translates into increased savings—
or profits—for owners, while improving water
quality at the same time.
For some, the misperceptions that pervious pavement doesn’t tolerate freeze-thaw
cycles, or that it can become clogged with
debris, have been stumbling blocks. But
anecdotal evidence shows that the pavements perform well in cold environments,
says Paul Tennis, consulting engineer for
PCA. The large voids prevent saturation and
allow the concrete to heat faster, melting
snow and ice and draining the liquid, so it
can’t linger in voids and cause cracking as the
temperatures cycle. And according to Wade,
while some pavements can become clogged,
the material can be vacuumed, bringing permeability back to levels close to those at
installation.
IN THE MIX: SUPPLEMENTARY
CEMENTITIOUS MATERIALS
Interest in using supplementary cementitious materials (SCMs) to enhance concrete’s
performance continues to grow. “SCMs can
increase the sustainable attributes of a green
building material like concrete in many
ways,” says Shepherd. “Optimized concrete
mixes with SCMs like slag cement, fly ash,
silica fume and others can provide enhanced
benefits, creating structures of the likes we
have never seen before.”
Jan Prusinski, executive director of the
Slag Cement Association (SCA), says the
hottest thing going in SCMs is ternary
mixes. “Ternary mixes that incorporate portland cement, slag cement, and fly ash are the
next wave in utilization of supplementary
cementitious materials,” says Prusinski.
“They are an excellent way to reduce the total
cement in a mix while improving durability.”
In fact, SCA has recently begun a two-year
research project (with Materials Service Life,
LLC) to examine the properties of ternary
mixtures with slag cement, portland cement,
and fly ash (classes C and F). The goal of the
research is to create a life cycle program to
help in optimizing mixes.
Using a performance-based approach for
specifying fly ash and other SCMs is key, says
Dave Goss, executive director of the American Coal Ash Association (ACAA). For example, while some state Department’s of Transportation (DOTs) specify 20 percent or 25
percent replacement with fly ash, there are
some applications where that isn’t enough
material to combat alkali-silica reactivity,
which can cause deterioration. Goss says the
industry must push for intelligent specifications. “One size doesn’t fit all.”
A longtime proponent of using fly ash in
concrete, Frentress says that in Glacier
North West’s market, the green building
movement has led to higher-than-normal fly
ash content specifications (30 percent to 50
percent) for sustainable commercial projects,
often made without consulting the readymixed concrete producers. “In our market,
the industry has experienced periodic fly ash
shortages, so we utilize what ash we can get
on a job in order to adhere to the specifications. When we don’t have enough ash, we
are forced to remove it from residential jobs
where it is not explicitly specified but is typically used,” he explains.
As a result, the larger volumes specified
often don’t have an additional positive effect
on the environment: “There really are no savings on CO2 reductions since the fly ash was
simply moved from one load of concrete to
another,” says Frentress. “In most cases in
our market, specifying over 30 percent fly
ash content can be too much of a good thing.”
A better alternative, he says, is for mix designs
to focus on performance, not on simply
including maximum SCMs to achieve recycled
content credits.
Like Prusinski, Goss says ternary mixes
are rapidly gaining in popularity. But many
state DOTs still do not allow ternary mixes,
according to Mark Luther, technical service
engineer for Holcim (US) Inc. It’s hard to say
when that might change. Even so, many
recent landmark projects have incorporated
SCMs, including Seven World Trade Center,
the Maumee River Bridge (the largest ever
built by the Ohio DOT), and the Oklahoma
Federal Building.
And manufacturers are becoming increasingly creative when it comes to using fly ash
and slag cement, using it more frequently for
structural fills, soil stabilization, road construction—even creating architectural elements with it. +
All editorial content within
the Concrete section was
written by Jennifer G.
Prokopy. As principal of
Orange Grove Media, an
independent communications firm, she provides
expert writing, editing and
Photo by James
Warden/Five Lake media relations services to
the construction industry.
Arts, Chicago
As president of the Construction Writers Association (CWA), Jenni
works with the nation’s top construction journalists and publicists to improve the quality of
construction communications. She is a winner
of the CWA Marketing Communications
Award, recognizing her writing on sustainable
construction with concrete, and a graduate of
Northwestern University’s Medill School of
Journalism.
EDC07054LEHI
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Deaf Northwest’s Chestnut Lane is an assisted living facility located in suburban Portland,
Ore., built mostly with concrete. Notable features include Arxx insulating concrete form walls,
concrete mixes with fly ash, pervious concrete pavement, and an impervious/waterproof concrete green roof. Photo courtesy of Glacier North West.
HOW DOES CONCRETE
FIT IN THE BIG PICTURE?
life cycle assessment: competing, evolving systems raise questions.
L
Life cycle assessment (LCA) is today’s sustainability buzzword. The
USGBC is preparing to integrate LCA into its LEED rating system, and
the industry is filled with lively debate about its impact. As LEED
matures and other rating systems find their place in the movement,
increasing emphasis is placed on the importance of examining all
aspects of a structure: not just the building itself, but the embodied
energy of materials, the long-term affects of manufacturing processes,
the stages of construction, building performance and operations, durability and maintenance of existing structures, and—in the end—demolition, materials recycling, and future land use ramifications. Although
LEED considers some of these, USGBC is considering more, and
whether the points are weighted correctly.
LCI, LCA: DEFINITIONS
The International Organization for Standardization (ISO) defines
LCA as the “compilation and evaluation of the inputs, outputs and the
potential environmental impacts of a product system throughout its
life cycle.” Life cycle inventory analysis (LCI), often confused with
LCA, is actually the phase of life cycle assessment involving the compilation and quantification of specific inputs and outputs—materials,
energy and emissions—for a given product system throughout its life
cycle. The difference is key: LCA is big picture; LCI trains a microscope
on individual components.
Rita Schenck, executive director for the Institute for Environmental
Research and Education (which helped to form the American Center for
Life Cycle Assessment in 2001), says LCAs are valuable because they are
fact-based. “It’s a measuring tool, pulling all the information into one
place,” she says. “An LCA shows you where you can really get better.
What has happened historically is that we move pollution from one type
to another, and an LCA can help make sure you’re not doing that.” (Her
www.EDCmag.com
for more information on conducting lcas
s8
• CTLGroup – www.ctlgroup.com
• Athena Sustainable Materials Institute – www.athenasmi.ca
• Institute for Environmental Research and Education – www.iere.org
• American Center for Life Cycle Assessment – www.lcacenter.org
• Portland Cement Association – www.cement.org/concretethinking
• BEES 3.0 – www.bfrl.nist.gov/oae/software/bees.html
• Green Globes – www.greenglobes.com
• USGBC/LEED – www.usgbc.org/leed
book, LCA for Mere Mortals, is a valuable tool for beginners—available
for download at www.iere.org.)
FROM DUST TO DEMOLITION: CONCRETE IN THE MIX
Concrete has something of a bad rap in certain circles. Some argue that
cement production releases CO2, that the embodied energy of the material is too high. But “the flip side to that is aggregate can be attained
locally, for lower transportation costs and pollution generated,” says
Schenck. And while cement does have a high embodied energy, it is only
a fraction of concrete, and its embodied energy is a fraction of the energy used to heat and cool buildings. Concrete can also contain recycled
aggregates (derived locally), recycled steel (derived locally), and supplementary cementitious mixtures (often industrial byproducts that would
otherwise be landfilled).
Concrete also brings numerous lasting benefits that many believe far
outweigh the front-end labor and energy. As Schenck mentioned, locally available materials mean less transportation and pollution. Concrete
also offers high thermal mass, contributing to energy efficiency and
comfort. Many concrete structures are designed for a 100-year life span.
The material’s light color can provide reflectivity that reduces air conditioning loads and helps reduce the urban heat island effect. And when a
project is demolished, much of the material can be recycled.
This is not to say that the cement industry is sitting on its laurels. On
the contrary, manufacturers are working harder than ever to make
processes cleaner and more efficient.
DANGER OF A NARROW FOCUS
CTLGroup is publishing a paper on the “Perils of Basing Sustainability
Decisions on Simple Metrics.” In response to many articles ranking one
product over another based on only a few metrics (embodied energy,
CO2 emissions, and the weight of raw materials), Authors Martha G.
VanGeem, principal engineer, and Medgar Marceau, building science
engineer, performed a full LCA of a house modeled with two types of
exterior walls, wood-framed and insulating concrete form (ICF).
Conducted according to ISO 14040 series guidelines, with energy
modeling based on Phoenix, Miami, Washington, Seattle, and Chicago,
the study showed that “the most significant environmental impacts are
not from construction products but from the production and
household use of electricity and natural gas.” The research shows
recycled, revitalized
concrete
end of the runway is not end of the life cycle for stapleton airport
In 1995, Stapleton International Airport was replaced with the ultramodern Denver International Airport. Although Stapleton had reached
the end of its service life, a massive materials recycling project is in
progress that will revive the area as a family-friendly residential and commercial community.
On completion, 975 acres of concrete and asphalt will be recycled,
yielding enough material to construct a two-lane roadway roughly
10,000 miles in length.
We Build
Sustainability
Building to preserve our precious natural resources means
looking no further than Reward Wall Systems. Our complete line of ICFs enables you to meet your clients’
demands for sustainable design — significantly reducing
the use of fossil fuels and wood during construction and
throughout the life of the structure — while keeping costs
At Denver’s now-closed Stapleton International Airport, 975 acres of concrete and asphalt
are being recycled. Recycled concrete aggregates can be used for road building or as aggregate
in new concrete construction. Photo courtesy of Recycled Materials Co., Inc.
basics of recycled concrete aggregates
Old concrete can be crushed and recycled into many applications. In the
U.S., the most popular is road building. A survey recently conducted by
the Federal Highway Administration shows that 38 states recycle concrete to create an aggregate base material; 11 recycle it into new portland
cement concrete.
Unprocessed recycled concrete aggregate (RCA) can be used as general bulk fill material, in bank protection, base or fill for drainage structures, road construction, noise barriers, and embankments. Processed
material can be used in new concrete for many transit applications, as
structural grade concrete, for soil-cement pavement bases, and more.
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A WEIGHTY ISSUE
David Shepherd, director of PCA’s sustainability program, says LCAs are
the next big battle ground for the green building movement. “LCA is the
tool that will allow people to evaluate and compare brand A to brand B,”
he says. The big question, he continues, is how boundaries will be set for
various impacts.
This is something with which VanGeem is becoming increasingly
familiar. VanGeem currently serves on an industry task group
addressing weighting issues related to USGBC’s LCA into LEED
Build Different. Build Better.SM
These products are covered by U.S. Patent #6,820,384
that studies that examine only a few components can make nearly
any product look bad; when the full range of effects is examined, it
might be hard to argue with the comprehensive results.
september 2005
leed points and other green benefits
Using recycled concrete aggregates (RCA) may help earn points toward
LEED credits, says Kerkhoff, both for incorporating recycled materials,
and for construction waste management. In addition, recycled aggregate
brings the same benefits of conventional concrete. For more on using
RCA, see ACI 555R-01: Removal and Reuse of Hardened Concrete. PCA
also has many resources on RCA at www.cement.org/tech.
in line with conventional building methods. In other
words, with Reward you’re able to compete on price, while
offering clients the advantages of building “green.”
s9
concrete
project. “Weighting is a subjective method
of giving relative importance to impacts
such as human health, climate change,
energy, scarce resources, etc.,” she explains.
Wayne Trusty, president of the Athena Sustainable Materials Institute, says that individ-
ual impact indicator methods use different
weighting criteria: “For example, when the
same LCI data was put through three different
impact indicator systems as part of a European LCA of highway construction, the systems produced three very different answers.”
He prefers to conduct LCAs with what he
calls the “food label approach,” one in
which all environmental ingredients and
influences are listed—allowing the organization (or owner, developer, etc.) to determine the weight of each component
according to their particular situation.
MULTIPLE SYSTEMS
www.EDCmag.com
Meanwhile, a number of green building
systems are currently available in the marketplace with LEED, each with its own take
on LCAs.
• BEES (Building for Environmental and
Economic Sustainability) 3.0 is a product-to-product materials comparison
tool developed by the National Institute
of Standards and Technology. (According
to VanGeem, it addresses only four possible concrete mixes out of thousands.)
• Green Globes is an online building and
management environmental audit, developed in Canada as a self-assessment tool.
• Athena Sustainable Materials Institute
offers the Environmental Impact Estimator, software that provides an LCA examination of conceptual building designs and
renovations of existing structures.
VanGeem says CTLGroup performs energy
analyses and uses a few different Europeandeveloped models to create LCAs, but reports
that American clients sometimes prefer not to
have a European-based approach. What the
North American industry needs, says
VanGeem, is a standardized LCA approach
that can be universally adopted. Shepherd
agrees: “A national organization will establish
standards eventually,” he says. But, the
process could take a while.
Meanwhile, members of the concrete
industry are working together to be better
neighbors, cleaner and more efficient in production, better at using recycled materials in
the production of cement and concrete, and
innovative in divining new uses for the world’s
oldest building material. Building a sustainable future is the driving force. “I’m really
impressed with what the concrete industry is
doing right now that is environmentally positive,” says Schenck. +
s10
concrete
IN CHICAGO,
CONCRETE CREATES
NEW OPPORTUNITIES
bethel center helps build a sustainable neighborhood
Photovoltaic cells at Bethel Center are one of its readily-visible
green building products. While not obvious, the concrete panels
that form the walls also contribute to its sustainability, increasing energy efficiency and improving indoor air quality. Photo by
Barry Rustin Photography.
A
A new project in Chicago’s West Garfield
Park is helping to revitalize the neighborhood, bringing much-needed daycare,
employment assistance, computer training,
retail, financial services and office space—
and uniting it with a recently renovated “El”
station linking the community to the rest of
the city. Dedicated May 19, the Bethel Center provides the neighborhood with an
anchor around which a more sustainable
community can be crafted. Concrete is a core
component of the structure, which strives
for Leadership in Energy and Environmental
Design (LEED) Gold certification.
TRANSIT-ORIENTED DEVELOPMENT
IN ACTION
FROM FOUNDATION TO ROOF,
CONCRETE BRINGS BIG BENEFITS
SAFETY, COMFORT AND ENERGY
Chicago Mayor Richard Daley is a proponent
of green roofs, so it was natural to install one
at Bethel Center. The presence of daycare
required a class 1 fire rating, but a concrete
roof eliminated the need for a costly sprinkler
system and also met the city’s strength criteria
(100 pounds per square foot) for green roofs.
When it comes to comfort, Bethel Center
has it, says Pierce. The thermal mass of concrete helps keep temperatures even and consistent, and blocks noise from busy adjacent
Pulaski Road and the El train. Stairs in the
building are pans filled with concrete.
The structure will provide its inhabitants
with a quiet setting for work and play, one
that stays cool in the summer and warm in
the winter. In fact, energy modeling (performed according to the Chicago Energy Conservation Code’s total building energy model)
shows that the Center exceeds requirements
by 50 percent, with projected annual energy
savings of $12,000.
For more information on Bethel Center,
visit www.bethelnewlife.org. +
Farr Associates of Chicago planned and
designed the project. The firm practices “socially and environmentally responsible architecture, planning, and preservation,” and its principals are actively involved in numerous planning committees to promote this mission.
Bethel Center, says principal Kevin Pierce,
goes “beyond the transit-oriented aspect of
environmentalism,” offering services rooted
in environmental justice and social equity.
Nelson says it shows how “a transit stop can
be a major asset in a community, providing
economic viability.”
Designed on a tight site, the two-story
building has a third-story portion that acts as
a lobby for the bridge from the El platform. A
steel structure forms the building’s shape, but
the rest of the structure is all about concrete.
The building is constructed on a brownfield
site, anchored by a foundation that incorporates 25 percent fly ash replacement in the
slab and footings.
The walls are manufactured using the
Solarcrete system. Seven-inch-thick slabs of
foam are wrapped with a reinforcing steel
cage; the pre-manufactured slabs are shipped
to the worksite and attached to the building
frame. The slabs are then covered with shotcrete (specified at 4,000 psi) in a layer about 2
inches thick, on either side of the wall, and
screeded off to create a smooth, level surface.
Because the shotcrete and steel frame will
experience independent thermal movement,
the shotcrete is separated from the frame. The
two concrete sides of each Solarcrete wall are
joined with nylon ties, in a perpendicular twofoot grid across the face of the wall, and the
units are finished with a layer of synthetic
stucco. The resulting walls offer a thermal
value of R-25.
Bethel Center also uses a precast concrete
plank floor and roof system. Utility conduit
was installed before the planks were finished
off with a two-inch topping slab, hiding utilities and keeping the ceilings uncluttered. “The
undersides of the planks are the finished ceilings—painted a clean white to get great reflective daylighting,” says Pierce.
The long plank design lent itself to a design
that includes holes for 4-foot by 10-foot skylight wells, one per 20-foot bay. This easy,
inexpensive approach means every top-floor
space enjoys daylighting, and helps reduce the
energy used by light fixtures.
september 2005
The project was created by Bethel New Life,
Inc., a community-directed non-profit organization that grew out of Bethel Lutheran
Church in the 1970s, and has since been an
innovator and motivator in the west side
neighborhood. Planning began almost 10
years ago, when the Chicago Transit Authority threatened to shut down the Green Line
serving the area. Protests led the city to save
the line, and Bethel New Life started planning
the building—which fit well with the organization’s sustainable goals.
Aligning the project with the El station was
key, says Mary Nelson, CEO of Bethel New
Life. In this community, only about 35 percent of residents have cars, so public transit is
a way of life for most. “We see this building, at
this transit stop, as an anchor,” says Nelson.
“We’ve built at least 50 new housing units
within walking distance as a part of the tran-
sit-oriented development. This new building
is just the first step, a wonderful stepping
stone to revitalizing the area.”
s11
KNOW YOUR
WALL SYSTEMS
Winner of the NCMA’s Award of Excellence in residential design, the Brems family house
in Salt Lake City demonstrates the sustainability of concrete. Photo courtesy of NCMA.
high-performance concrete comes in many varieties,
including these six popular systems by jennifer g. prokopy
W
When it comes to using concrete wall systems in sustainable building
construction, the options are limitless. There are many types of walls,
and within each category, many variations.
TILT-UP
Tilt-up concrete walls have been used for a century; today, more than 15
percent of industrial buildings in the U.S. are made with tilt-up concrete
panels, according to the Tilt-Up Concrete Association (TCA). When
building with tilt-up, the site is prepared, walls are cast on-site on the
floor slab, and then—just like the name says—tilted up and secured
in place. The panels can be finished in myriad ways.
Tilt-up systems offer many environmental benefits, says TCA executive director Ed Sauter. Because they are cast on-site, transportation
costs are minimized. Typically, the thermal mass of tilt-up eliminates
the need for insulation. Of the approximately 25 percent of panels
that are insulated, most use non-conductive ties to take best advantage of thermal mass properties—creating solid, insulated walls that
offer high energy efficiency. The large panels (the record is just over
90 feet tall) require minimal energy and labor when it comes to erection and finishing. And tilt-up buildings can be designed to accommodate change, with panels easy to remove and reuse, or even recycle
if necessary. Visit www.tilt-up.org.
INSULATING CONCRETE FORMS
Long the province of residential builders, insulating concrete forms
(ICFs) are rapidly gaining popularity in commercial construction. The
stay-in-place forms are placed in the shape of a structure and connected with plastic ties, and reinforcing steel is installed to provide
additional support. Concrete is pumped into the forms and allowed to
set, creating a wall with foam insulation on each side, sandwiching the
reinforced concrete core.
According to the Insulating Concrete Form Association (ICFA), the
high R-value of the insulation, the thermal mass of the concrete, and
the ability to moderate temperature swings, make the system ideal for
climates with large temperature variations—but ICFs may increase
energy efficiency in any region. The forms can be installed quickly
and easily, and the wide variety of manufacturers, shapes and sizes
makes it easy to custom-design homes and smaller commercial
structures. Visit www.forms.org.
PRECAST
www.EDCmag.com
Precast concrete panels are used for both structural and architectural
applications, primarily in commercial structures. Components are precast at a manufacturing facility and transported to the site. Precast walls
offer high durability and strength plus thermal mass, which contributes
to increased energy efficiency. They also use locally derived materials,
and can incorporate recycled materials like fly ash and slag cement.
According to the Precast/Prestressed Concrete Institute (PCI),
one of the biggest benefits of precast walls is in their design: tight controls mean more efficient mix designs, resulting in smaller structural
members and longer spans. Construction waste is reduced, because
the exact amount of necessary components is delivered to the site.
Any spare components can easily be recycled. Creative precast wall
design can also reduce material redundancy. Visit www.pci.org.
MASONRY
Concrete masonry units are available in a rainbow of colors, textures,
shapes and sizes. They can be used to create structural walls in residential and commercial applications or to build other structures like
retaining walls or hardscaping.
s12
REMOVABLE FORMS
Concrete walls built with removable forms
(also called vertical-pour walls) are used both
above- and below-grade, primarily in residential applications, according to the Concrete
Foundations Association (CFA).
There are a variety of systems—some that
place concrete on two sides sandwiching
foam in the middle, and some that place
insulation on one side and concrete on the
other—but the basic process is the same.
E X P E C T
M O R E
F R O M
Walls built with autoclaved aerated concrete
(AAC) typically are constructed in a fashion
similar to masonry, with blocks held together by mortar, but these blocks are made with
only fine aggregates, cement, lime and a nat-
Y O U R
ural expansion agent that causes the concrete to “rise,” filling it with tiny air pockets.
The resulting material is lightweight and
easy to work with.
AAC comes in wall, floor and roof panels,
cladding pieces, and specialty shapes, according to the Autoclaved Aerated Concrete Products Association (AACPA). Ronald Barnett,
vice president and general manager of manufacturer AERCON Florida, LLC, says one significant benefit of AAC is cost, especially for
fire walls, which can be constructed 4 inches
thick to achieve a four-hour UL fire rating.
The material’s lighter weight means shipping costs, fuel and pollution are reduced.
The durable material will last indefinitely,
and thin mortar joints help provide a tight
building—and excellent indoor air quality. In
some areas, AAC even incorporates fly ash,
mine tailings, slag cement and other byproducts that would otherwise be landfilled. Visit
www.aacpa.org. +
B U I L D I N G S
september 2005
Achieve up to 21
AUTOCLAVED AERATED CONCRETE
LEED points
with Quad-Lock ICF
QUAD - LOCK BUILDINGS ARE :
• Safe: We offer exceptional protection
from Mother Nature and the test of time.
• Healthy: Airtight walls reduce air
infiltration, create a mold-free environment
and eliminate drafts and cold spots.
• Responsible: Less energy and water are
used in our manufacturing processes;
construction waste can be recycled.
“
Find Out More Today
888-711-5625
info@quadlock.com
Without the energy-saving qualities of
Quad-Lock walls, there’s absolutely no way
we could have submitted these homes for
LEED Certification.
”
JIM HANNA
DIRECTOR,ENVIRONMENTAL AFFAIRS
XANTERRA PARKS & RESORTS
FOR YELLOWSTONE NATIONAL PARK
concrete building solutions
concrete
Aluminum forms are placed, filled with concrete, and removed once the material sets,
leaving solid structural walls. The aluminum
forms can be used up to 3,000 times and are
recyclable at the end of their service life.
Although vertical-pour walls historically
have been used for external walls, Ed Sauter,
executive director of CFA, says that some
companies are now introducing systems for
interior walls and decks, which, when used
together, produce a total concrete shell poured
in a single operation. Innovators are also refining the product to create walls that use less
concrete but offer the same performance
characteristics. Visit www.cfawalls.org.
According to the National Concrete
Masonry Association (NCMA), concrete
masonry units offer sustainable benefits,
including eliminating the need for VOCemitting paints. Concrete masonry units create walls with high thermal mass. Masonry
offers durability and sound attenuation. For
hardscaping applications, concrete landscaping units help to reduce stormwater runoff and
support plant growth. Visit www.ncma.org.
www.quadlock.com
s13
CEMENT PLANTS
GOING GREEN
I
In April, Portland Cement Association (PCA) and Cement Americas
magazine recognized five cement plants for getting greener. The
Fourth Annual Cement Industry Environment and Energy Awards recognize individual facilities that exemplify the spirit of continuous environmental improvement and support this spirit with action.
Tom Carter, director of environment, health and safety for PCA, says
the awards have become a point of pride for companies: “People are taking a much more holistic approach to energy management, realizing that
if they look at the big picture, they can significantly reduce emissions and
save a lot of money,” says Carter. The changes are far-reaching.
“Any community activities are great, but combined with environmental programs, they’re even better,” he explains. “Companies are
getting more involved in sharing environmental success stories
with the community, and listening to their community’s environmental concerns.” When it comes to land stewardship, more companies are going beyond beautification, creating wetlands, restoring habitats, and otherwise enhancing the interaction between the
facility and the eco-system.
Two of the five 2004 winning facilities are highlighted below:
California Portland Cement Co. and St. Lawrence Cement.
CALIFORNIA PORTLAND CEMENT CO.
– COLTON, CALIF.
The Energy Efficiency Award evaluates energy planning, applications
of efficient technologies and practices, and climate change mitigation
efforts. Using the Environmental Protection Agency’s ENERGY STAR
program as a guide, the facility implemented a corporate energy management program and team.
The plant’s policy establishes baseline energy use, sets goals based
on benchmarking and industry best practices, requires periodic audits
to determine savings opportunities, implements energy saving ideas,
and provides training and awareness of energy efficiency best practices.
The implementation of this program resulted in an energy consumption reduction of 4.5 percent from 2003 levels, which translates into
savings of $842,000. In March, California Portland was also named an
ENERGY STAR Partner of the Year.
ST. LAWRENCE CEMENT
www.EDCmag.com
s14
– MISSISSAUGA, ONTARIO, CANADA
The Overall Environmental Excellence Award recognizes environmental achievement in several areas. The facility won the Environmental
Performance category, which honors facilities that take steps beyond
those contained in environmental laws, regulations, permits, and
requirements to minimize their impact on the environment.
In 2004, the facility implemented an environmental management
system and was the first cement plant in North America to achieve ISO
14001 certification. The plant took numerous steps to drastically cut
emissions, minimize waste, and reduce natural resource consumption.
St. Lawrence also was the runner-up for the outreach, innovation
and energy efficiency categories. For more information on the winning
plants, visit www.cement.org. +
EDC09054LFRG
8/23/05
9:29 AM
Page 1
performance
solutions
ınnovations
Lafarge believes sustainability can be a competitive
Our products — including our recycled content
advantage. A member of the U.S. Green Building
materials and blended cements — contribute a
Council (USGBC), Lafarge works with other industry
sustainable component to a growing number of
leaders to promote buildings that are environmentally
North American projects.
responsible and healthy places to live and work.
And our employees are entering the Council’s
Increasingly, Lafarge products play a central role in
LEED Professional Accreditation program, earning
sustainable architecture and construction— projects
the designation to better serve the environmental
built under the Council’s Leadership in Energy and
needs of the design and building industry, today
Environmental Design Program (LEED).
and in the future.
Lafarge North America is the U.S. and Canada’s largest diversified supplier of construction materials such as cement, ready-mixed concrete, gypsum wallboard, aggregates,
asphalt and concrete products. The company’s materials are used in residential, commercial, institutional and public works construction across Canada and the U.S.
For more information about our sustainability initiatives, visit us online
at www.lafargenorthamerica.com.
©2005 Lafarge North America Inc.
EDC09054PCA
8/10/05
9:04 AM
Page 1

s1 Concrete Cvr - Specify Concrete

Transcription

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