wednesday march 6, 2013 case study: high rap pilot … · case study: high rap pilot project ....
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Wednesday March 6, 2013 Case Study: High RAP Pilot Project
Contractor Perspective: Dan Karcher, R.E. Pierson Materials
Acknowledgements R.E. Pierson Materials Arawak Paving Nustar Asphalt New Jersey Asphalt Paving Association Rowan University Rutgers University New Jersey Department of Transportation
Plant Quality Control Training on best practices for managing RAP
Consistency Plant component changes
Dillman drum and multiple RAP bins, Astec Fractionating System Addition of third liquid asphalt tank
Best Practices For Managing RAP Inventories
Avoid contamination Mix as you feed Don’t under-process Don’t process when it rains Blend again when moving Fractionating
Pros & Cons
Quality Control Testing Testing and analyzing of all materials Consensus properties Asphalt binder content
Ignition oven and solvent extraction Rowan University
Leave no stone unturned
Superpave High RAP Mix Designs Purpose
Minimize the stress, maximize performance, and minimize maintenance cost
Four high RAP mix designs HMA 9.5M76 20% RAP (Nustar PG76-22) HMA 9.5M76 30% RAP (Nustar PG76-22) HMA 12.5M64 30% RAP (Nustar PG58-28) HMA 12.5M64 40% RAP (Nustar PG58-28) Approved for volumetrics by NJDOT Region South
Materials
Checking Volumetrics By Performance Tests
Performance Tests Asphalt Pavement Analyzer Overlay Tester
Requirements HMA 9.5M76 High RAP Surface Course
APA Rutting <4.0mm Overlay Tester Fatigue >175 cycles
HMA 12.5M64 High RAP Intermediate Course APA Rutting <7.0mm Overlay Tester Fatigue >100 cycles
Trial and Error PG Grade NMAS RAP % OT(cycles) APA Rutting 58-28 12.5mm 30% 1442 9.28mm 58-28 12.5mm 40% 503 8.56mm 76-22 9.5mm 20% 365 5.53mm 76-22 9.5mm 30% 129 4.37mm Address rutting concern
Reference NCHRP 673
Adjusting Mix Designs to Improve Rut Resistance
Increase the binder high-temperature grade If the binder is not modified, consider using a polymer-
modified binder of the same grade or one high-temperature grade lower
If the binder is polymer-modified, try a different type of modified binder
Increase the amount of mineral filler in the mix, adjusting the aggregate gradation if necessary to maintain adequate VMA
Decrease the design VMA value Replace part of the aggregate (fine, coarse, or both)
Continuing Performance Testing PG Grade NMAS RAP% OT APA Rutting 64 HRAP 1 12.5 40% 80 5.94mm 76 HRAP 1 9.5 30% 121 3.66mm 64 HRAP 1 12.5 35% 560 PASS 76 HRAP 1 9.5 25% 320 PASS Passed performance testing requirements of NJDOT
HMA High RAP Specification
High RAP Mix Designs For Production
Ensure quality Produce mixes on private sector
Utilizing pre-crushed RAP Same RAP used for lab work
HMA 12.5M64 Plant Produced High RAP 6.62mm rutting 752 OT cycles
HMA 9.5M76 Plant Produced High RAP 6.02mm rutting 982 OT cycles
HMA 12.5M64 PASSED HMA 9.5M76 FAILED – Try Again Possible binder contamination – mix checked at 300 and 450 ton locations APA 2.72mm, OT cycles 169. Some passed, some failed
Ready For Job Site Plant quality assurance/quality control results
complied Plant produced mix complied with performance
requirements Field results complied for air voids and ride quality
Final Results Performance
HMA 9.5M76 25% RAP 1691 OT Cycles 3.56mm Rutting
HMA 12.5M64 35% RAP 409 OT Cycles 6.57mm Rutting
Compaction Average of HMA 9.5M76 High RAP surface course density is
6.7% air voids for two lots Average of HMA 12.5M64 High RAP surface course density is
5.6% air voids for three lots
Final Results (cont.) Inconsistencies with surface course air voids resulted
in pay disincentive Consistent results with intermediate course air voids
resulted in pay incentive Ride quality
Average IRI 54.3 – pay incentive
Time To Follow Through HMA 12.5M64 intermediate course can be used as
surface course with 35% RAP and still meet performance criteria
HMA 9.5M76 surface course with 25% RAP possible replacement of HPTO Thin Overlay Cost savings without jeopardizing performance
Balancing High RAP mix designs Better Roads – Upping the RAP article