SUSTAINABLE CONSTRUCTION
with Coal Combustion
Products
A Primer for Architects Produced by the American Coal Ash Association Educational Foundation www.acaa-usa.org
Building a Sustainable Future Our built environment has implications for
Coal combustion products (CCPs), often
the sustainable use of natural resources,
referred to as “coal ash” are materials
energy consumption and carbon emissions. Over half of the world’s population now lives in urban areas, and
produced when coal is burned to generate electricity. Each year in the U.S., coal-fueled power plants produce over 110 million tons of CCPs. About 40% of CCPs are recycled
by 2050 over two-thirds of the global
annually into concrete and a variety of green
population will be urban. Sustainable
building products.
building practices are vital for protecting the
Products made with CCPs in place of mined
natural environment while supporting livable
or manufactured materials perform better,
cities and long-term economic viability.
cost less, and decrease environmental impacts. Concrete made with coal fly ash
Substituting recycled industrial materials
is stronger and more durable than concrete
for conventional products in construction
made with cement alone. And the
results in tremendous environmental and
environmental benefits of CCP recycling are
economic benefits including improved
huge: for every ton of coal fly ash used as
technical performance and longevity; decreased water, energy and land use;
a replacement for portland cement, approximately one ton of greenhouse gas emissions are prevented. Annually, this
reduced emissions; and lower construction
reduces carbon emissions by 13 million
costs. One such recycling success story
tons–equivalent to taking 2.5 million cars
is coal combustion products.
off the road.
Fly Ash - Improving Strength Fly ash is a powdery material that is captured by emissions control equipment before it can “fly” up the power plant stack. Mostly comprised of silica, alumina and calcium compounds, fly ash has mechanical and chemical properties that make it a valuable ingredient in concrete, providing long-term structural strength. Fly ash concrete is less permeable and more resistant to acid, sulfates and other destructive chemical reactions than concrete made with cement alone. Fly ash lowers the heat of hydration, improves workability, and reduces shrinkage and cracking. More than half of the concrete produced in the U.S. contains fly ash, used for roads, bridges, buildings and concrete blocks. Builders routinely specify 40 percent fly ash in concrete mixes, but 70 percent or more in high volume
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applications has been used where structural stability is paramount.
Synthetic Gypsum - from Floor to Ceilings
Boiler Slag Lasting Durability
Power plants equipped with flue gas desulphurization (FGD) emissions controls, also known as scrubbers, create byproducts that include synthetic gypsum. Although this material is not technically “ash� it is classified as a coal combustion product. Scrubbers utilize high-calcium sorbents, such as lime or limestone, to absorb sulfur and other elements from the flue gases. Synthetic gypsum is used in nearly 30 percent of wallboard manufactured in the U.S. The use of synthetic gypsum avoids the mining of virgin gypsum, yielding water, energy and emissions reductions. Synthetic gypsum has also been used for cement production, self-leveling flooring applications and as an agricultural amendment to treat poor soil conditions, improving crop yields.
Boiler slag is molten ash collected at the base of older boilers that is quenched with water and shatters into black, angular pieces having a smooth, glassy appearance. Boiler slag is typically used for roofing granules, asphalt coatings and blasting grit.
Bottom Ash - Filling Many Needs Bottom ash is a heavier, granular material that is collected from the bottom of coal-fueled boilers. Bottom ash is often used as an aggregate to replace sand and gravel, and as an ingredient in masonry products including concrete blocks. Bottom ash has also been identified as an excellent growing medium for green roofs, providing water retention benefits.
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Reaching New Heights with CCPs
One World Trade Center
Wilshire Grand Center
Burj Khalifa Tower
At 1,776 feet high, One World Trade
The foundation for the 73-story Wilshire
The tallest man-made structure in the
Center in New York City is one of the
Grand tower in Los Angeles was
world, Burj Khalifa towers 2,722 feet
greenest super-tall buildings in the U.S.
specifically designed to absorb ground
above Dubai, UAE. To achieve the
movement during earthquakes and enable
structural strength needed to withstand
the building to withstand severe
high winds and support the building’s
windstorms. The tower’s foundation is a
massive weight, the tower was designed
concrete slab utilizing high quality fly ash
with a “Y” shaped buttressed core
as a 25% substitution for portland cement
constructed with high performance fly ash
to improve structural strength and
concrete. The concrete mix was designed
concrete saved about 6000 tons of carbon
durability. The foundation for the Wilshire
to provide low permeability and high
dioxide emissions, 8 million kWh of
Grand set a world record for the largest
durability. Two of the largest concrete
energy and 30,000 gallons of fresh water.
continuous concrete pour of 21,200 cubic
pumps in the world delivered the
The high-strength fly ash concrete
yards. Fly ash was essential to the
concrete mix to heights over 2000 feet.
enabled the design to use smaller
project’s success because it mitigates
Over 330,000 cubic yards of concrete was
structural supports in columns and
the heat of cement hydration in such a
used in the construction of Burj Khalifa.
walls, yielding more livable floor area.
large-scale pour.
The design had unique durability and sustainability requirements, including using high-strength “green concrete” utilizing fly ash and slag. The concrete mix tripled the compressive strength of conventional concrete, up to 14,000 psi (pounds per square inch). The green
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Beauty in Sustainable Design with CCPs Oakland Cathedral To create lightness and space, the Cathedral of Christ the Light in Oakland, California used architecturally-exposed reinforced concrete made with fly ash. A main design objective of the cathedral was to have the smallest environmental footprint possible, so the use of recycled fly ash achieved both strength and sustainability objectives.
Shri Swaminarayan Mandir (12) by 4nitsirk/CC 4.0
BAPS Temple The BAPS Hindu Temple in Chicago was built with
Aqua Tower The design inspiration for the
high volume (65%) fly ash concrete for the reinforced foundation, beams and shear walls to achieve a 1,000 year service life.
82-story Aqua Tower in Chicago was eroded rocks found around the Great Lakes. The wave-like balconies were created by unevenly pouring different mixtures of concrete, with the gray concrete containing more fly ash while the lighter concrete contains more portland cement.
Arizona Residence This residence designed by Arizona architect Michael Frerking was
Milwaukee Art Museum
constructed using “poured earth”
The Milwaukee Art Museum was constructed with
made with 67 percent fly ash to
high volume fly ash to achieve a variety of important
substantially reduce the building’s
design objectives. To create the unique sculptural
carbon footprint and minimize
Quadracci Pavillion, concrete was poured into
energy use.
one-of-a-kind wooden forms.
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Programs Supporting CCPs Wall-Form Products Most of these products have hollow interiors and are stacked or set in place and can be filled with high volume fly ash steel-reinforced concrete. Fly ash and bottom ash are also used extensively in grouts and masonry products, including concrete veneer stone, available in a wide range of color options.
Flooring Applications Many builders are using CCP- based floor underlayments in construction, to address a variety of flooring situations and challenges. Self-leveling underlayments may be placed to aid in preparation of the floor prior to installation of the finished floor systems. Over-layments are sometimes specified to correct defective flooring issues prior to installation of carpeting, tile, wood or other surfaces. These applications also can provide sound insulating features. For examples of these applications see www.maxxon.com/go_green. Fly ash and synthetic gypsum are used widely in commercial applications, and can be used in single-family and multi-family homes to support LEED or Green Globes’ points for indoor environmental quality, low emitting materials, recycled content, regional materials and innovation in design.
Masonry Products
Masonry Products Fly ash and bottom ash are used extensively in grouts and masonry products, including concrete veneer stone, available in a wide range of color options.
Site Preparation CCPs have many uses when preparing a project site for development. Fly ash can be used to stabilize and solidify soils at Brownfield sites or in construction areas. If rains have made work areas difficult to access by vehicular traffic, self-cementing fly ash or fly ash combined with portland cement, cement kiln dust or lime kiln dust can dry up these areas quickly and economically. Blending self-cementing fly ash with existing soils allows for the stabilization of roads and parking areas prior to paving. When embankments or structural fills are needed, fly ash, bottom ash and boiler slag can be combined with earthen materials to meet engineering specifications for compaction,
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Ceiling Tiles & Pan Products
Ceiling tiles and
with fly ash and
can be textured
compressive strength, grain size distribution and other
with a wide rang
geo-technical considerations.
different archite
in Sustainable Architecture’
nel
Green Roofs Diagram courtesy U.S. EPA
Typically, green roofs are part of a normal roof system which involves green space on top of a building. Green roofs are usually modular in design allowing plants to be planted in movable sections or containers. A waterproof barrier separates the green roof from the structural roof. The units containing plants have a drainage system, filter cloth and lightweight growing media to allow the plants to establish their roots. Green roofs can provide a wide range of benefits including aesthetic appeal, energy conservation, noise reduction, preventing water runoff, and improved air quality. Green roofs typically require less maintenance and are longer lasting than conventional roofs, and help reduce carbon emissions. Because of its lightweight, granular characteristics, bottom ash is an ideal material for part of the growing media. For more information: www.greenroofs.com and www.greenroofs.org
Carpet Backing Backing comprised of recycled materials can take years of abuse without sacrificing performance. The inherent “ball-bearing” effect resulting from the spherical nature of the glass particles of fly ash contribute to better packing factors in various polymer systems. For carpet backing systems, this translates to improved flammability ratings, better tuft binds, and improved dimensional stability. As a bonus to the performance characteristics fly ash imparts to these engineered systems, carpet backings qualify or LEED Materials and Resources credits for recycled content, and under NSF/ANSI 140 standards for sustainability.
Composites Fly ash also serves as filler in wood
Geotechnical Geotechnical applications include soil stabilization, road base,
products, countertops, plastic
engineered structural fill, and embankments. The use of CCPs in
products, paints, and metal castings.
controlled low-strength materials (CLSM), sometimes called flowable fills, provides economic alternatives to many backfill situations. When utility trenches are constructed at a job site, often the dirt or
d wall products made
earthen materials excavated are removed immediately. This
d synthetic gypsum
necessitates importing fill materials once the trench work is complete.
d and pigmented
Rapid setting flowable fills made with fly ash, bottom ash and cement
ge of colors for
ectural features.
(if needed) can be used to efficiently close the exposed work areas allowing the surface to be finished rapidly.
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Certifying the Safety and Benefits of CCPs
LEED V4
LEED Platinum Bardessono hotel
LEED Platinum home in Mill Valley, California. Image credit: Mariko Reed Photography
Leadership in Energy and Environmental
toward certification in the categories of
gypsum products also earn credits.
Design (LEED) is a green building
Sustainable Sites, Water Efficiency, Energy
Innovative design strategies can garner
certification program developed by the
and Atmosphere, Materials and Resources,
additional credits, including reducing
U.S. Green Building Council that recognizes
Regional Priority, Innovation, and Indoor
carbon emissions through the use of high
best-in-class building strategies and
Environmental Quality.
volume fly ash concrete, fly ash bricks
practices. LEED v4 is the newest
and other recycled products made with
version of this global benchmark for
Concrete containing at least 25% fly ash is
CCPs. Using CCPs in pervious pavements,
high-performance green buildings. To
considered by LEED as an environmentally
which reduces the rate and quantity of
receive LEED certification, a building must
preferable product, earning credits in the
storm water runoff, can contribute to
attain a specific number of credits, with
Materials and Resources category.
earning LEED credits in the categories
Silver, Gold and Platinum levels
Materials that limit the extraction of raw
of Sustainable Sites, Water Efficiency,
r epresenting advanced certification. Using
materials such as synthetic gypsum
and Materials and Resources.
CCPs in construction can earn credits
wallboard as a replacement for mined
Please visit www.usgbc.org/v4
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Environmental Product
Greenprint: Denver, Colorado Declarations
Demonstrating Safety
An Environmental Product Declaration
The U.S. Environmental Protection Agency
(EPD) is an independently verified
(EPA) has conducted a thorough scientific
and registered document quantifying
evaluation of the safety of using fly ash in
the full life-cycle environmental performance of a product, evaluated in accordance with ISO standards. EPDs are based on product
concrete and synthetic (FGD) gypsum in wallboard, finding that releases of constituents of potential concern are comparable to or lower than those from analogous products made without CCPs,
category rules (PCR) that define
or are at or below relevant health-based
the requirements for EPDs of a
benchmarks. In its 2014 published beneficial
certain category. CCP products that
use evaluation report, EPA concluded that
have EPDs include fly ash bricks
these uses “contribute significant
and carbon-neutral “green cement”
environmental and economic benefits” and
made with 95% fly ash. EPDs allow consumers to compare the environmental performance of products made with CCPs to analogous non-CCP products.
that “the Agency believes that these beneficial uses provide significant opportunities to advance Sustainable Materials Management.” See: http://www. epa.gov/waste/conserve/imr/ccps/pdfs/ ccr_bu_eval.pdf
Green Globes
The Reagan Building in Washington D.C., headquarters for EPA, was constructed with fly ash concrete.
The Green Globes building rating and
in building construction can help score
certification program was developed
points related to site development,
by the Green Building Initiative and is
materials and resources, energy
accredited by the American National
consumption, water use, emissions,
Standards Institute (ANSI). Green
and indoor environments.
Globes evaluates the environmen-
Green Globes provides early feedback
tal friendliness and sustainability
in the construction process, before
of building projects. As with LEED,
critical final decisions are made.
Green Globes promotes green building
Independent, third-party assessors
practices that yield energy efficiency,
are used in the rating. Green Globes
emissions reductions, water savings,
has been recommended by the U.S.
use of recycled and reclaimed materi-
General Services Administration (GSA)
als, healthier indoor environments, and
as one of two certifications (with LEED
reduced ecological footprint. Green
being the other) for evaluating the
Globes assesses building environmen-
performance of federal government
tal impacts on a 1,000-point scale in
agency buildings Please visit
seven categories. Utilization of CCPs
www.greenglobes.com
Perot Museum in Dallas holds the highest Green Globes certification
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The Future of CCPs in Sustainable Construction Coal combustion products are projected to continue to play a major
tons in 2033 and production of synthetic gypsum is projected to
role in sustainable construction over the next 20 years. Utilization
grow from 35.2 million tons in 2013 to 38.8 million tons in 2033, as
of coal combustion products in major markets has grown by an
shown in the chart below.
average of 4.7 percent a year since 1974, increasing to over 51 mil-
Ash beneficiation and other emerging technologies are
lion tons recycled during 2013. CCP utilization has increased during
expanding the use of CCPs into new markets and products,
three of the last five recessions since 1974 as markets have taken
ensuring dependable, high quality CCPs will be available well
advantage of the lower cost of CCPs compared with alternative
into the future. Producers and marketers are working together to
materials. The figure below shows the production and utilization of
ensure CCPs will continue to comply with applicable construction
CCPs since 1990.
standards and specifications.
Despite retirements of coal-fueled power plants over the last few
As sustainable construction becomes more important, more and
years, coal is expected to remain a primary energy source in the
more architects, construction firms and consumers have come to
U.S. for decades to come, according to the U.S. Energy Informa-
recognize the environmental, economic and sustainability benefits
tion Administration (EIA). Coal will account for the largest share of
that CCPs deliver. Science and practical experience has trans-
electric generation through 2040. As a result, fly ash production
formed the perception of fly ash and other CCPs from waste to
is forecast to grow from 53.5 million tons in 2013 to 54.9 million
valuable product.
Change to Utilization of CCPs 60 55 50
Fluidized Bed Combustion
Short Tons (Millions)
45
Flue Gas Desulfurization
40
Boiler Slag
35
Bottom Ash
30
Fly Ash
25 20 15 10 5
Data Years
10
20 05
20 02
19 99
19 96
19 93
19 90
19 87
19 84
19 81
19 78
19 78
19 75
19 72
19 69
19 66
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Sustainable Building Resources The American Coal Ash Association (ACAA)
Green Globes is an online green building
LEED green building certification program,
advances the management and use of coal
rating and certification tool licensed for use
administered by the U.S. Green Building
combustion products in ways that are
in the U.S. by the Green Building Initiative.
Council (USGBC), is the premier bench-
environmentally responsible, technically
The Green Globes New Construction as-
mark recognizing best-in-class sustainable
sound, commercially competitive, and
sessment can be used for a wide range of
building strategies and practices. To receive
more supportive of a sustainable global
commercial, institutional and multi-residen-
LEED certification, building projects satisfy
environment. www.acaa-usa.org
tial building types to advance sustainability
prerequisites and earn points to achieve
and environmental goals. Visit: www.
different levels of certification.
greenglobes.com or www.thegbi.org
Visit: www.usgbc.org/leed
several standards, including ASTM C618,
Specific guidance on the use of high
The National Association of Home Builders
ACI 232.2 and ACI 232.3. Marketers of fly
volume fly ash can be found in a book
(NAHB) ToolBase is the housing industry’s
ash will commit to the quality specified as
by V.M. Malhotra and P.K. Mehta,
best resource for technical information on
they supply fly ash to ready mix producers,
High-Performance, High-Volume Fly Ash
building products, materials and new tech-
who in turn ensure the concrete will meet
Concrete, 3rd Ed. This book contains
nologies. ToolBase Resources combines
the designer’s needs through their own
mix designs, recommendations,
product descriptions, design & construc-
quality program. Visit: www.astm.org/Stan-
precautions and examples of high volume
tion guides, best practices, performance
dards/C618.htm and www.concrete.org
fly ash concrete placement and
reports, case studies, and other resources
for more information on the standards.
applications.
in a way that builders and remodelers will
The BEES: Building for Environmental and
The Industrial Resources Council (IRC)
Economic Sustainability Software devel-
Is a collaboration of non-profit industry
The National Ready Mix Concrete
oped by NIST brings to your fingertips a
associations working together to promote
Association (NRMCA) has guidance
powerful technique for selecting cost-ef-
the appropriate use of industrial materials,
documents available that define the quality
fective, environmentally preferable building
including coal combustion products. Visit:
requirements for all concrete mix designs,
products. Visit: www.nist.gov/el/econom-
www.industrialresourcescouncil.org
including those using fly ash or slag. Visit:
The quality and characteristics of fly ash as a component of concrete are defined in
find useful. Visit: www.toolbase.org
ics/BEESSoftware.cfm
www.nrmca.org The International EPD® System library
Best Practices Guide for High-Volume Fly
contains environmental product declara-
Oikos is an online directory for green
Ash Concretes: Assuring Properties and
tions (EPD) listed by product category and
building products. Please visit:
Performance is published by the National
country. Information on creating and using
www.oikos.com
Institute of Standards and Technology
EPDs and product category rules (PCR) is
(NIST). The best practices guide considers
available at: www.envirodec.com
Sustainable Sources is an online source for
all aspects of high volume fly ash (HVFA)
green building information, including fly ash
concrete production from materials char-
concrete related information. Visit: www.
acterization through curing to long-term
sustainablesources.com
performance. NIST Technical Note 1812 is available at http://concrete.nist.gov/~bentz/ NIST.TN.1812.pdf
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Coal Combustion Products Build Sustainable...
Residences
Masonry Products
Office Buildings
Government Structures
Skyscrapers University Facilities
ervious and P Asphaltic Pavements
Bridges
Churches and Temples
Concrete Floors
Composite Products
Airports
Green Roofs
Dams and Reservoirs
Stone Veneers
Stadiums and Arenas
Plastic and Mineral Fillers
Outdoor Sports Complexes
Wallboard Panel Products
Tilt-up Buildings
Museums
Tunnels and Roadways Monuments
andscaping Applications L ...and much more.
American Coal Ash Association Educational Foundation 38800 Country Club Drive,Farmington Hills, MI 48331 720.870.7897 info@acaa-usa.org All of the images contained in this document are of buildings constructed using coal combustion products. Printed on recycled paper. 12