The Massachusetts Concrete

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(No Transcript)
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The Massachusetts Concrete Aggregate Producers
Association

• Members Meeting
• Kens Stake house
• Framingham Ma
• January 29. 2009

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Recycled Concrete
By David Gress Recycled Materials Resource
Center Department of Civil Engineering Univers
ity of New Hampshire

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Acknowledgements

• Federal Highway Administration
• Recycled Materials Resource Center

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Recycled ConcreteWhat is it?

• NCHRP 4-21
• Demolition by-product of old concrete structures
• Roadways
• Sidewalks
• Foundations
• Retaining Walls
• Concrete Pipe
• Roadway Medians
• Catch Basins
• etc
• Properly processed can be used as a substitute
  aggregate material
• ACI 116
• Hardened concrete that has been processed for
  reuse, usually as aggregate

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Recycled Aggregate Products

• Road Base
• Dry Screened Rock
• Structural Backfill
• Landscape Stone
• Vehicle Tracking Rock
• Trail Surfacing

• Ready Mixed Concrete
• Top soil amendments
• Under Slab Bedding
• Drainage Rock
• Stackable Landscape Stone
• Pipe Bedding

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Architectural Uses
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Pavement Uses

• I 84 Waterbury Connecticut

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Pavement Uses

• SR 59 Minnesota
• Doweled and Ground

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Structural Use
Enterprise Park Building Denver 8,000- yd3
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Where Do We Get It?

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Does Source Matter?YES

• Aggregate size/properties
• Cement type, W/C
• Air entrained
• Distress (D cracking, ASR, freeze thaw damage,
  sulfate attack)
• Environmental exposure
• Type of structure
• May contain contaminants (soil and asphalt)

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Opportunity or mess, where do you begin?
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Conventional equipment works
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RCA Stockpiles Ready for use
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Denvers Stapleton International Airport

• Opened in 1929
• Closed 66 years later (1995)
• Concrete averaged 24 inches thick
• Covering 975 acres
• 6.5 million tons of aggregate recycled
• Worlds Largest Recycling Project
• Enough aggregate to build the Hoover Dam, and at
  no cost to the city of Denver!

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A Recycling Pioneer
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How did they do it? 13,000 Guillotine

Capable of Crushing gt30 of pavement
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Crusher Feed Stock
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Steel is magnetically removed and sold for scrap

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RCA Base Course
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Construction Materials Recycling Association
Estimates

• More than 140 million
• Tons per Year are produced in the US
• http//www.cdrecycling.org/

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Physical Properties

• Grading (Same as conventional)
• Specific Gravity (increases with size 2.0-2.5)
• Shape (more angular, good)
• Texture (rougher, good)
• Moisture Content (higher due to absorption)
• Compacted Density (optimum w higher)
• Absorption (decreases with size, 8 to 2)

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Mechanical Properties

• Strength (CBR 90 to 140) Equal
• Abrasion Loss (LAB 20 to 45) Increases
• Soundness (NaSO4 test not valid)

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Chemical Properties

• pH gt 11 (no buffering capacity but corrodes
  aluminum)
• ASR (possible but can be mitigated)
• Tufa (white powdery precipitate)
• Salt (from deicing salts)

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Deleterious Materials

• Soil
• Asphalt concrete
• Brick
• Solid waste and hazardous materials
• Wood, metal, plaster and gypsum

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Application and Performance

• Portland Cement Concrete (equal)
• Hot Mix Asphalt (absorption of asphalt )
• Embankment or Fill (added value maybe too high
  for use)
• Miscellaneous Aggregate (equal to or better)
• Granular Base (equal to better)

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Benefits

• Comparable to conventional aggregate
• Can be very cost effective (1/2 /-) especially
  in urban areas
• Increases life of landfills
• Preservation of natural aggregates
• Environmentally Green

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Obstacles

• Need a specification for use
• Must recognize differences
• Q/C Q/A
• Education/learning curve
• Commitment to use must be made

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Future Recycling of Concrete

• Increased quantity of RCA will come primarily
  from non-DOT sources
• 85 of PCC is owned by private, municipal or
  county agencies
• Need exists for standards and specifications to
  control quality of RCA obtained from multiple
  sources

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RCA Web Sites

• Recycled Materials Resource Center
• http//www.rmrc.unh.edu
• Federal Highway Administration
• http//www.fhwa.dot.gov/pavement
• Environmental Council of Concrete Organizations
  (ECCO)
• http//www.ecco.org
• King County, Washington
• http//www.metrokc.gov/procure/green/concrete.htm
  
• Recycled Materials Company, Inc.
• http//www.rmci-usa.com
• Portland Cement Association
• http//cement.org

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P

PaLATE
Pavement Life-cycle Assessment Tool for
Environmental and Economic Effects Developed by
the University of California, Berkley for RMRC
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WWW.RMRC.unh.edu

• A computer based decision support tool to
• model economic costs and environmental
• effects of using traditional highway
  materials and recycle materials for highway
  applications.
• Audience Pavement designers and engineers,
  transportation agency decision-makers, civil
  engineers, and researchers

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Environmental Output Data

• Energy MJ
• Water Consumption kg
• CO2 Mg emissions Global Warming Potential
  (GWP)
• NOx kg emissions
• PM10 kg particulate emissions
• SO2 kg emissions
• CO kg emissions
• Hg g emissions
• Pb g emissions
• RCRA Hazardous Waste Generated kg
• Human Toxicity Potential (Cancer)
• Human Toxicity Potential (Non-cancer)

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Environmental Output Resultsfor Initial
Construction and Maintenance

• Materials
• Production
• Transportation
• Processing

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Example for Carbon Footprint Comparison

• Interstate Highway 4 lanes separated with 4 and
  10 paved shoulders 1 mile long
• PCC 12 thick on 10 base
• PCC shoulders 6thick on 6 base

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Cases evaluated

• Case 1 New construction
• Case 2 Recycle Case 1 as unbound base
• Case 3 Case 1 recycled into concrete

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Case 1 New Construction

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Case 1 New Construction

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Case Comparison

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CO2 Release New Construction vs. Unbound Base
and Recycled Concrete

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Conclusions

• Recycling Concrete significantly reduces the
  Carbon Footprint
• Using RCA in Concrete reduces the Carbon
  Footprint more than when used as Unbound Base

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