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In-Situ Recycling
• Reduced material buy
• Reduced haul cost
• Reduced haul damage
• Reduced traffic congestion
• Reduced project duration
• More value
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CIR-EAM
• Treats all existing pavement distresses
• Flexible – avoids rigid or semi-rigid
behavior
• Treated material approaches plantmix
strength
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Caltrans vs Local Agencies
• Different Needs and Goals
• Different Approaches
• Different Staffing
• Different Budgeting
• Different Accountability
• Different Appetite / Need for Risk
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Section Design
• Caltrans method doesn’t recognize the
true properties of CIR-EAM Interim Report on I-80 in Placer County – 2006
“Conservative approach” estimated Gf of 1.4, even though
worst-case prediction from actual material testing resulted
in Gf of 1.8
UCPRC Guidelines – 2009: Gf of 1.4
Caltrans Maintenance FDR Using Foamed Asphalt –
2012: Gf of 1.4
Less than a 30% improvement over AB
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Recent research – AASHTO ‘93 Structural
Coefficients
• Foamed Asphalt report at the Mid-Continent
Transportation Research Symposium 2003 –0.18 –
50% improvement over AB
• Kowalski & Starry, 2007 – 0.13 to 0.36
• Wirtgen Cold Recycling Manual, 2012 – up to 0.35
• Maryland SHA, 2013 – 0.30 to 0.35
• Khosravifar, Schwartz, and Goulias, 2015 –
International Journal of Pavement Engineering – 0.36
Three times stronger than AB and approaching HMA
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AASHTO ‘93
• World-wide use
• Based on full-
scale testing
• Supporting
research on-
going
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AASHTO ‘93
• More focused
look at traffic
• No arbitrary SG
strength
limitation
• Material
variability
• Overall reliability
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Updated AC and CIR-EAM Strengths
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“Equivalent” Designs
R-value 70 – 121,000 ESALs – TI of 7.0
AASHTO ‘93 Caltrans
Chip Seal over 3.5” CIR-EAM
2” HMA over 6.5” CIR-EAM
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R-value 70 – 5,400,000 ESALs – TI of 11.0
AASHTO ‘93 Caltrans
2” HMA over 3.5” CIR-EAM
6”
HM
A o
ver
8”
CIR
-EA
M
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307-213-0223 [email protected] ©Mike Robinson, PE
You can still use the Caltrans Method
• Stick with their VERY conservative value
• Use a higher value based on some
interpolation
It basically all comes down to risk.
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Changes
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“Throw a couple of bags of cold mix in that
pothole…”
Photo courtesy of Dustin Hamilton
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Mike Robinson LLC
101 Upper Canyon Loop
Ten Sleep, WY 82442
(307) 213-0223 [email protected]