SEPA
United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(OS-305)
EPA/530-SW-91-086
January 1992
Office ol Solid Waste
Environmental
Fact Sheet
EPA Guideline for Purchasing Cement
And Concrete Containing Fly Ash
Coal fly ash, like portland
cement and volcanic ash, is
composed of mineral matter
mainly in the form of oxide
compounds derived from
limestone, iron ore, silica
sand, and clay. Fly ash has
been used for decades in the
production of durable and
economical concrete, and can
be purchased either in
blended cement or as a
mineral admixture for
concrete.
Coal Fly Ash Uses
In the 1960s, the American
Society for Testing and
Materials (ASTM) developed
standards! for the use of fly
ash in concrete that are
updated annually (see box on
Standards and Availability).
The application and
performance of concrete
containing fly ash has been
documented by both the U.S.
Bureau of Reclamation and
the U.S. Army Corps of
Engineers since the 1940s.
Over the last 40 years,, fly ash
has been used in virtually
every concrete market,
including highways, airports,
commercial and residential
buildings, bridges, pipelines,
and tunnels. Widely available
in the United States, more
than six million tons of coal
fly ash are used annually in
cement and concrete (see box
on Standards and
Availability).
Equal or reduced cost of
total materials can be realized
with the use of fly ash while
maintaining or improving
concrete properties. In cases
where no cost savings are
realized by using fly ash, it
may be advantageous since
fly ash can improve both the
strength and durability of
concrete.
Coal fly ash is also used in
mixtures designated by ACI
as controlled low-strength
material (CLSM). CLSM
mixtures are typically used to
fill trenches or other
excavations like mine shafts
and in abandoned
underground storage tanks.
CLSM mixtures are
proportioned with fly ash,
sand, water, and small
amounts of portland cement.
A CLSM mixture is fluid and
self-compacting, and can be
proportioned to produce
strengths equivalent to
compacted soil.
Procurement Guideline
To increase the use of
cement and concrete
containing fly ash from coal
combustion within both
government and private
sectors, on January 28,1983,
EPA issued a guideline for
purchasing cement containing
fly ash. It requires all federal
agencies and all state and
local government agencies
and contractors that use
federal funds to purchase
cement and concrete to
implement a preference
program favoring the
purchase of cement and
concrete containing coal fly
ash.
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Coal Fly Ash
Specifications
Coal fly ash reacts
chemically with portland
cement and water to form
compounds possessing
cementitious properties. The
amount of fly ash in typical
concrete applications is from
15 to 35 percent, by weight of
total cementitious material,
with amounts up to 70
percent and more in massive
walls, girders, road bases, and
dams.
Two general methods are
used to incorporate coal fly
ash in concrete mixtures: (1) a
prescriptive method in which
fly ash replaces a fixed
portion of the portland
cement and (2) a design
method in which fly ash use is
based on laboratory or field
records to produce an
optimum effect on concrete
properties and performance.
Each method has a valid
place in engineering practice.
With either method, the main
requirement for assuring
satisfactory workability,
strength, and durability is not
to exceed a mflyimnm ratio of
water to cementitious
material [w/(c+f)]» where w, c,
and f represent the weights
of water, portland cement,
and fly ash, respectively.
More information about fly
ash use in concrete is
available from the American
Concrete Institute (ACI) (see
Standards and Availability
below).
Further Information
For further information,
including copies of the cement
and concrete procurement
guideline, please contact
EPA's procurement guidelines
hotline at (703) 941-4452.
Information on Standards and Availability
ASTM C 595, "Standard Specification for Blended Hydraulic Cements," American Society for Testing
and Materials, annual book of ASTM Standards, part 14.
ASTM C 618, "Standard Specification for Fly Ash and Raw or Calcined Natural Pozzolan for Use as a
Mineral Admixture in Portland Cement Concrete," American Society for Testing and Materials, annual
book of .ASTM Standards, part 14.
NCHRP Synthesis 127, Use of Fly Ash in Concrete, National Cooperative Highway Research Program,
Transportation Research Board, October 1986.
FHWA-DP-59-8, Fly Ash Facts for Highway Engineers, Federal Highway Administration, July 1986.
ACI 226.3R-87, "Use of Fly Ash in Concrete," American Concrete Institute, 1987.
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