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Coal Combustion Products: American Coal Ash Association Presents Geotechnical Uses for CCPs David Goss Executive Direct...

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Coal Combustion Products: American Coal Ash Association Presents

Geotechnical Uses for CCPs David Goss Executive Director American Coal Ash Association

Coal Ash vs. CCPs ƒ Coal combustion products are residuals from the combustion of coal and emission control systems: – Fly ash – FGD (synthetic) gypsum – Bottom ash and boiler slag – Air emission control system residues (other FGD co-products) ƒ “Coal Ash” and “CCPs” have been terms used interchangeably; CCPs now apply to both ash and FGD byproducts

Fly Ash ƒ Fine particles like flour or talc ƒ Exhibits “pozzolanic” characteristics – Siliceous or siliceous and aluminous materials, when in the presence of water, react with calcium hydroxide to produce cementitous properties ƒ Besides natural ash, there are two types – Class F from bituminous coal (lignite?) – Class C from sub-bituminous coal (lignite?)

What Makes Fly Ash Useful? ƒ Non-hazardous nature ƒ Mineralogical and pozzolanic characteristics allow it to be used in lieu of other natural materials ƒ Spherical shape ƒ Easily transportable ƒ Can be conveyed dry or in moistened form

Fly Ash Benefits ƒ Additive to concrete as a replacement for portland cement – Enhances durability – Reduces permeability – Improves workability ƒ Makes good concrete better ƒ Potential economic savings at time of placement and through life cycle

Bottom Ash ƒ Heavier than fly ash and granular in nature. Can be used: – as raw feed for cement production – in soil applications to improve drainage and blended with other materials for composting – in masonry blocks and concrete products – in road base and mineral fillers in asphalt – as a component of artificial aggregates

Structural Applications ƒ Highway overpasses, embankments, railroad realignments and new track work; also in mining ƒ Serves as low-cost material that be blended with available borrow materials ƒ Standards & guidelines established by ASTM International & others ƒ Large volumes of CCPs can be used

Structural Fill Guidance Information ƒ ASTM E2277-03 addresses: – Engineering properties and behavior of CCPs – Testing procedures – Design considerations – Construction techniques ƒ Technical information and Case studies can be found at: http://www.epa.gov/epaoswer/osw/conserve/c2p2 – Recycled Materials Resource Center

Some Examples of Large Projects ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Rostraver Airport, Pennsylvania Interstate 76/270 - Denver, CO Crites Field Waukesha, WI Jackson County, Missouri Phoenix links, Pennsylvania Interstate 279 – Pittsburgh, PA Washburn Airport, North Dakota Asphalt rehabilitation - Delaware and Warren counties, Ohio

Soil Stabilization ƒ Fly ash alone (Class C) or with portland cement, CKD or lime can b used to modify soils – To dry wet working areas – To increase stiffness – Reduce permeability – Reduce plasticity and swelling – Control compressibility and moisture ƒ Typically more economical than just portland cement

Stabilization Guidance ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

ACAA’s Soil Stabilization manual Iowa State work funded by FHWA University of Wisconsin – Madison TxDOT State of Missouri Various conference proceedings DOE funded research University of North Dakota studies Recycled Materials Resource Center

Environmental Benefits of CCPs ƒ ƒ ƒ

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Reduces greenhouse gas emissions Conserves natural resources Reduces energy impacts of extraction and processing Cuts down on need for landfill space

Outreach and Partnerships ƒ Wide dissemination of accurate information ƒ Joint industry and government information exchange partnerships ƒ Face to face technology transfer ƒ Collaborative relationships among organizations with allied interests

Green Highway Partnership ƒ Public-Private sector “Green Highway Forum” – Environmentally sensitive context for planning, design. Construction and maintenance of roadways – Use and reuse of industrial materials, biofuels, minimize impact on land ƒ Being developed by industry, EPA, FHWA, AASHTO, AGC, etc. ƒ www.greenhighways.org

Publications ƒ“Soil Stabilization and Pavement Recycling with Self-Cementing Coal Fly Ash” (ACAA) ƒ“Fly Ash Facts for Highway Engineers” (FHWA) ƒUsing Coal Ash in Highway Construction: A Guide to Benefits and Impacts” (US EPA) ƒ“Leaching of Heavy Metals from Fly Ash Stabilized Soils Used in Highway Pavements” (DOE-CBRC) ƒ“In Situ Stabilization of Gravel Roads with CCPs” (DOE CBRC)

More Publications ƒ“User Guidelines for Waste and By-Product Materials in Pavement Construction” (FHWA) ƒ“Fly Ash Soil Stabilization for Non-Uniform Subgrade Soils” (FHWA) ƒ“Guidelines for Modification & Stabilization of Soils and Base for Use in Pavement Structures” (TxDOT) ƒ“ASTM 2277-03 – Standard Guide for Design and Construction of Coal Ash Structural Fills” ƒ“High Volume Fly Ash Utilization Projects in the US and Canada” (EPRI)

Web Links ƒ American Coal Ash Association: www.acaa-usa.org ƒ United States Environmental Protection Agency, Office of Solid Waste: http://www.epa.gov/epaoswer/osw/conserve/c2p2/ ƒ University of Kentucky Center for Applied Energy Research International Ash Utilization Symposium Ash Library: http://www.flyash.info ƒ University of North Dakota EERC Coal Ash Resources Consortium: http://www.eerc.und.nodak.edu/carrc/index.html ƒ University of Wisconsin Milwaukee Center for By-Products Utilization: http://www.uwm.edu/Dept/CBU ƒ West Virginia University Combustion Byproducts Recycling Consortium: http://wvwri.nrcce.wvu.edu/programs/cbrc/index.cfm

Conclusions ƒ CCPs can be used safely and in lieu or other natural materials in many applications ƒ There may be some economic advantages to using fly ash and/or bottom ash ƒ Technical guidance and many assessments of environmental impact are available from academic and regulatory sources

Conclusions ƒ CCP use directly supports and contributes to a more sustainable environment ƒ Sound technical, environmental and operational procedures can address perceptions and potential objections ƒ Properly managed applications will achieve desired physical, environmental, economic and social results

Coal Combustion Products: Geotechnical Uses for CCPs

Thank You

David Goss Executive Director American Coal Ash Association 720-870-7897