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Superpave Today Kenneth Ray Hobson, P.E. –Bituminous Engineer City of Tulsa May 13, 2011.

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Presentation on theme: "Superpave Today Kenneth Ray Hobson, P.E. –Bituminous Engineer City of Tulsa May 13, 2011."— Presentation transcript:

1 Superpave Today Kenneth Ray Hobson, P.E. –Bituminous Engineer City of Tulsa May 13, 2011

2 Overview Asphalt Mix Design Methods Laboratory Mixture Compactors Asphalt Binders Aggregate Tests Mix Design Proof Testing Design by Traffic Volume

3 Overview Mix Design Notes Future Items of Note 2009 Std. Spec. 411 Links Of Note


5 Automatic Marshall Hammers

6 Texas Gyratory Hveem Compactor

7 Superpave Gyratory Compactor (SGC)

8 Limitations of Traditional Binder Specifications Penetration & ductility tests are purely empirical Tests are conducted at one standard temp (i.e ºF), despite different climatic conditions Entire range of pavement temperatures (esp. low temps) not considered

9 Limitations of Traditional Binder Specifications Asphalt cements can have different temperature and performance characteristics within same grade (Pen or Vis) Not applicable to modified binders (more use in recent years) E.g. Grades AC-20, PMAC-1C

10 Superpave Asphalt Binder Specification The grading system is based on Climate PG Performance Grade Average 7-day max. pavement temperature Min. pavement temperature

11 Performance Graded Binder Specifications Based on Mechanical Properties (DSR, BBR) o Modulus o Deflection o Load Response (Rate) Other Tests Remain Unchanged o Mass Change, Flash Point, Elastic Recovery, etc. ER is known as PG+ Spec. ODOT 2009 Std. Spec Table 708:2

12 Aggregate Tests Superpave similar to Hveem with added tests: o Fine Aggregate Angularity (FAA) o Bulk Specific Gravity (used for FAA and VMA computations) o Micro-Deval (30+ MESALs)

13 Mix Design Proof Testing Marshall Cohesiometer Hveem Stabilometer Hamburg Rut Test

14 Design by Traffic Volume Hveem – ADT o Lab Specimens (4 diameter) Compacted the Same (275 o F) o Air Void Limits Adjusted by Traffic Superpave –ESALs in 20 Years o Lab Specimens (6 diameter) Compacted More with More Traffic (300 o F) o Air Void Limits Kept Constant

15 Mix Design Notes Ndes – Number of SGC Gyrations at JMF Binder Nini – Number of SGC Gyrations backcalculated from Ndes Specimens o Density Similar to That Behind Paver Nmax – Number of SGC Gyrations at End of Pavement Life (mix design only)

16 Future Items of Note WMA – The Future is here now! o Provides Many Benefits Tack Coats – 0.15 gal/SY Diluted 1:1 o Trackless Tack Emulsion – Near 100% Bonding o Pave Sprayer Applied PMCRS-1S – Near 100% Bonding

17 2009 Std. Spec. 411 Table 411:2 – Calculate Density (RD) Based on Latest Gse at JMF Binder Content for Pay Factor Table 411:4 – Binder Content (Pb) and Air Voids (AV) for Pay Factors CPF = (4 x RD + (3 x AV) + (3 x Pb)) / 10

18 Future Items of Note Increased Binder Content by Special Provision o Possible Reduction in SGC Gyrations o Possible VMA Increase by 0.5%

19 Links of Note Construction Engineering o Standards, Specifications, Materials and Testing Materials Division Contacts o Materials & Testing e-Guide o

20 Links of Note Guidelines (Binder Selection and Thickness by Type) o Approved Performance Graded Binders and Others o BIT.htm BIT.htm Approved Superpave Mix Designs o Years of Transportation 1911 – 2011 o

21 Links of Note Approved List of Anti-Strip Additives and WMA Technologies o ASA.htm ASA.htm WMA Special Provisions o xspn pdf xspn pdf o p_ pdf p_ pdf WMA – Information in Detail o

22 Summary Asphalt Mix Design Methods o Superpave Most Common in History Laboratory Mixture Compactors o New SGC Compacts 6 Diameter Specimens Asphalt Binders o Performance Graded Using Mechanical Properties Aggregate Tests o Little Added Mix Design Proof Testing o Rut Testing Prevents Premature Failure

23 Summary Design by Traffic Volume o Based on ESALs for 20 Years Mix Design Notes o SGC Gyrations Critical for Predictive Performance Future Items of Note o WMA – Adopted Nationwide Faster than Superpave

24 Summary 2009 Std. Spec. 411 o Pay Factors – Increased for Density by 10% and Removed Gradation Links Of Note o Sources for Additional Information o Updated Daily as Applicable

25 Special Thanks Danny Gierhart, P.E. – Former Bituminous Engineer and Current Regional Asphalt Institute Engineer Reynolds H. Toney, P.E., Materials Division Engineer Audience o Especially Those with Questions

26 Questions?

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