Concrete Recycling in Pavement Applications
Tara Cavalline, Ph.D., P.E. UNC Charlotte tcavalline@uncc.edu
Presentation to National Concrete consortium September 20, 2017
Concrete Recycling in Pavement Applications Update on the FHWA - - PowerPoint PPT Presentation
Concrete Recycling in Pavement Applications Update on the FHWA Concrete Recycling Initiative Tara Cavalline, Ph.D., P.E. UNC Charlotte tcavalline@uncc.edu Presentation to National Concrete consortium September 20, 2017 Concrete Recycling
Presentation to National Concrete consortium September 20, 2017
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– Program Goals: Encourage innovation and extended application of sustainable pavement technologies on projects
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(FHWA, 2004 + new info)
6 48.3 13.7 10.8 0.7 10 20 30 40 50 60
Subbases & bases Granular shoulders Embankment and backfill Erosion control In new concrete Percent of Projects
7 Application Percentage (% use) Granular subbase 40 Crushed products for other markets 18 Embankment (includes backfill) 12 Coarse concrete aggregate 9 Other (given to owner agency) 7 Chemically stabilized granular subbase (CTB, lean concrete etc.) 4 Haul road 3 Granular shoulder material 3 Fine concrete aggregate 2 Surplus fines 1 Erosion control applications Plant site subbase 1 Slope stabilization materials Underdrain filter material Rip rap
8 0 = Not a significant barrier 5 = Critical barrier or very high importance
1.9 2.5 1.7 2.3 2.0 1 2 3 4 5 ASR, D-cracking of source concrete Gradation issues, particularly fines RCA foundation strength and/or stability Environmental impacts (runoff, leachate, etc.) Economics (cost of producing RCA)
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3.5 2.6 3.0 2.4 2.9 2.9 3.3 1 2 3 4 5 ASR, D-Cracking Shrinkage Workability Strength Lack of guidance on mix designs Economics Good, inexpensive natural sources
0 = Not a significant barrier 5 = Critical barrier or very high importance
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Constructed Using RCA
– Guidelines for Removing and Crushing Existing Concrete Pavement – Guidelines for Using RCA in Unstabilized (Granular) Subbases – Guidelines for Using RCA in Concrete Paving Mixtures – Relevant AASHTO/ASTM Standards – Glossary of Terms and Index
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recycling – economic – sustainability
– economic analysis – environmental assessment – rating systems
sustainability assessment tools for concrete recycling projects – general considerations – considerations specific to concrete recycling
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Photos: Phillip Lamoureux, FHWA Western Federal Lands (top), Steven Theisen, WisDOT (below)
recycling – economic – sustainability
– economic analysis – environmental assessment – rating systems
sustainability assessment tools for concrete recycling projects – general considerations – considerations specific to concrete recycling
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Photos: Phillip Lamoureux, FHWA Western Federal Lands (top), Steven Theisen, WisDOT (below)
use of RCA in different applications – Materials considerations – Production considerations – Other considerations
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Characterization of the Source Concrete Production Options for RCA Economics Other Factors Potential Recycling Project Identified Project Scoping Completed
– Lean concrete subbase and cement-stabilized subbase – Asphalt concrete and asphalt- stabilized subbase
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– Performance concerns
– Qualification testing
soundness, etc.) – Subbase design and construction considerations – Concrete pavement design considerations – Environmental considerations
Includes example projects for each application
– Fresh properties
– Hardened properties
RCA – Qualification Testing – Proportioning
– D-cracking aggregate – ASR – Continuously reinforced concrete pavement
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– particle degradation during roll- down – moisture-density control – other concerns
– gradation – Absorption – LA abrasion/MicroDeval – unconfined compression – Other tests
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considerations
environmental concerns – water quality – air quality – noise/local impacts – waste generation
– Focus on water quality issues
– Strategies for mitigating issues on-site
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Photo: Dwayne Stenlund, MnDOT
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Photo: CDRA
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