1. Volumetric Properties of High RAP Mixtures Based on Calculated Bulk Specific Gravities of RAP and Constituent Aggregates Nassim Sabahfer Mustaque Hossain, Ph.D.,P.E. Department of Civil Engineering Kansas State University

2. Outline ● Background ● Problem Statement ● Objective ● Methodology ● Laboratory Testing ● Results ● Conclusions & Recommendations ● Acknowledgements 2

3. Background - Reclaimed Asphalt Pavement (RAP) ● Approx. 100 million tons of RAP produced each year and 80 million tons are reused ● Useful alternative to virgin aggregates in HMA:  Reduces cost  20% RAP with 5% binder  1% savings in new binder  Enables recycling  Conserves energy RAP Stockpile at Shilling Construction Co., Manhattan, KS

4. RAP Usage in the US

5. Problem Statement ● Superpave mix design is predominantly used now and permits use of RAP ● Superpave volumetric mix design is highly dependent on properties like VMA, VFA, and Dust-to-Binder Ratio ● These parameters need blend bulk aggregate specific gravity in the calculation process ● RAP aggregate specific gravity is tricky

6. Objectives ● Compare RAP aggregate bulk specific gravity (Gsb) obtained from various methods ● Investigate influence of this Gsb on the calculated VMA ● Investigate effect of asphalt absorption assumption ● Study RAP maximum theoretical specific gravity (Gmm) as RAP Gsb

7. Methodology ● Choose RAP sources (5) ● Run maximum specific gravity tests (Gmm) on two replicates of each RAP ● Obtain RAP aggregates via (a) extraction and (b) ignition oven burn off ● Sieve into coarse (plus #4) and fine (minus #4) fractions ● Run bulk specific gravity tests and compare ● Compute VMA and compare

8. RAP Gradations (12.5 mm NMAS)

9. Measured RAP Properties Source of RAP Binder Content (%)* Average G mm Asphalt Absorption (Initial Assumption) (%) US-56 5.182.4241.5 US-59 6.862.4701.5 US-73 5.772.3421.5 Konza 4.202.4771.5 Shilling 5.802.4391.5 * Ignition oven

10. Gmm Test (KT-39)

11. Coarse and Fine Aggregates in RAP Materials RAP Source Ignition OvenSolvent Extraction % Coarse% Fine% Coarse% Fine US-56 36643169 US-59 31692971 US-73 30702179 Konza 34663070 Shilling 28722575

12. RAP Aggregate Bulk Specific Gravity ● Method #1 ● Split extracted aggregates into coarse and fine fractions ● Determine bulk specific gravity of each fraction ● Method #2 ● Same as #1; use burned off aggregates

13. RAP Aggregate Bulk Specific Gravity

14. Aggregate Specific Gravity Test Results

15. Statistical Analysis ● Comparison of Gsb Test methodCompared toReject H 0 G se Ignition ovenYes G se Solvent extractionYes G se RAP G mm Yes Ignition ovenSolvent extractionNo Ignition ovenRAP G mm No Solvent extractionRAP G mm No

16. Changes in Gsb as a function of asphalt absorption

17. VMA Obtained Using Gsb from Different Methods (Konza RAP)

18. VMA Obtained Using Gsb from Different Methods (Shilling RAP)

19. Statistical Analysis VMA obtained fromCompared toReject H 0 G se Ignition ovenYes G se Solvent extractionYes G se RAP G mm Yes Ignition ovenSolvent extractionNo Ignition ovenRAP G mm No Solvent extractionRAP G mm No

20. Differences in calculated VMA as a function of RAP content

21. Conclusions ● Gsbs obtained from the ignition oven and solvent extraction methods are similar but both are different from that based on Gse ● Statistically RAP Gmm is not significantly different from Gsb obtained from the ignition oven or solvent extraction method ● VMA obtained from Gse-based Gsb is significantly different from the VMA’s obtained from other Gsbs ● Difference in VMA increases considerably as the RAP content increases

22. Recommendations ● RAP aggregate Gsb using either from the extraction or the ignition oven test method should be used in design of Superpave mixtures with RAP

23. Acknowledgements ● This study has been sponsored by the Kansas Department of Transportation (KDOT) ● Project Monitor: Brian Coree, Ph.D., P.E.

24. Thank You