superpave today kenneth ray hobson, p.e. –bituminous engineer [email protected] city of tulsa may...
TRANSCRIPT
Superpave Superpave TodayToday
Kenneth Ray Hobson, P.E. –Kenneth Ray Hobson, P.E. – Bituminous Bituminous EngineerEngineer
[email protected]@odot.org
City of TulsaMay 13, 2011
OverviewOverview• Asphalt Mix Design Methods• Laboratory Mixture Compactors• Asphalt Binders• Aggregate Tests• Mix Design Proof Testing• Design by Traffic Volume
OverviewOverview• Mix Design Notes• Future Items of Note• 2009 Std. Spec. 411• Links Of Note
Automatic Marshall Automatic Marshall HammersHammers
Texas Gyratory Hveem Texas Gyratory Hveem CompactorCompactor
Superpave Gyratory Superpave Gyratory Compactor (SGC)Compactor (SGC)
Limitations of Limitations of Traditional Binder Traditional Binder
SpecificationsSpecifications• Penetration & ductility tests are
purely empirical• Tests are conducted at one
standard temp (i.e.. Pen @ 77ºF,Vis @ 140ºF), despite different climatic conditions
• Entire range of pavement temperatures (esp. low temp’s) not considered
Limitations of Limitations of Traditional Binder Traditional Binder
SpecificationsSpecifications• 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
Superpave Asphalt Superpave Asphalt Binder SpecificationBinder Specification
The grading system is based on Climate
PG 64 - 22
Performance Grade
Average 7-day max. pavement
temperature
Min. pavement
temperature
Performance Graded Performance Graded Binder SpecificationsBinder Specifications
• Based on Mechanical Properties(DSR, BBR)oModulusoDeflectionoLoad Response (Rate)
• Other Tests Remain UnchangedoMass Change, Flash Point, Elastic Recovery, etc. ER is known as PG+ Spec.• ODOT 2009 Std. Spec. 708.03 Table 708:2
Aggregate TestsAggregate Tests
• Superpave similar to Hveem with added tests: oFine Aggregate Angularity (FAA)oBulk Specific Gravity (used for
FAA and VMA computations)oMicro-Deval (30+ MESALs)
Mix Design Proof Mix Design Proof TestingTesting
• Marshall Cohesiometer• Hveem Stabilometer• Hamburg Rut Test
Design by Traffic Design by Traffic VolumeVolume
• Hveem – ADToLab Specimens (4” diameter)
Compacted the Same (275oF)oAir Void Limits Adjusted by Traffic
• Superpave –ESALs in 20 YearsoLab Specimens (6” diameter)
Compacted More with More Traffic (300oF)
oAir Void Limits Kept Constant
Mix Design NotesMix Design Notes
• Ndes – Number of SGC Gyrations at JMF Binder
• Nini – Number of SGC Gyrations backcalculated from Ndes SpecimensoDensity Similar to That Behind Paver
• Nmax – Number of SGC Gyrations at End of Pavement Life (mix design only)
Future Items of NoteFuture Items of Note
• WMA – The Future is here now!oProvides Many Benefits
• Tack Coats – 0.15 gal/SY Diluted 1:1oTrackless Tack Emulsion – Near
100% BondingoPave Sprayer Applied PMCRS-1S –
Near 100% Bonding
2009 Std. Spec. 4112009 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
Future Items of NoteFuture Items of Note
• Increased Binder Content by Special ProvisionoPossible Reduction in SGC
GyrationsoPossible VMA Increase by 0.5%
Links of NoteLinks of Note• Construction EngineeringoStandards, Specifications, Materials
and Testing• http://www.okladot.state.ok.us/cnstrctengr.htm
• Materials Division Contactso http://
www.okladot.state.ok.us/materials/index.htm
• Materials & Testing e-Guideo http://www.okladot.state.ok.us/materials/material
s.htm
Links of NoteLinks of Note• Guidelines (Binder Selection and Thickness by
Type)o http://
www.okladot.state.ok.us/materials/pdfs/GUIDE-01.pdf
• Approved Performance Graded Binders and Otherso http://
www.okladot.state.ok.us/materials/htm-smap/11062p-BIT.htm
• Approved Superpave Mix Designso http://www.okladot.state.ok.us/materials/acmixportal.htm
• 100 Years of Transportation 1911 – 2011o www.okladot.state.ok.us/odot100
Links of NoteLinks of Note• Approved List of Anti-Strip Additives and WMA
Technologieso http://www.okladot.state.ok.us/materials/htm-smap/
11062p-ASA.htm
• WMA Special Provisionso http://www.okladot.state.ok.us/c_manuals/
specprov2009/pdfs/xspn411-13.pdfo http://www.okladot.state.ok.us/c_manuals/
specprov2009/oe_sp_2009-708-22.pdf
• WMA – Information in Detailo http://warmmixasphalt.com/
SummarySummary• 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 Testso Little Added
• Mix Design Proof Testingo Rut Testing Prevents Premature Failure
SummarySummary
• Design by Traffic VolumeoBased on ESALs for 20 Years
• Mix Design NotesoSGC Gyrations Critical for
Predictive Performance• Future Items of NoteoWMA – Adopted Nationwide Faster
than Superpave
SummarySummary
• 2009 Std. Spec. 411oPay Factors – Increased for
Density by 10% and Removed Gradation
• Links Of NoteoSources for Additional InformationoUpdated Daily as Applicable
Special ThanksSpecial Thanks
• Danny Gierhart, P.E. – Former Bituminous Engineer and Current Regional Asphalt Institute Engineer
• Reynolds H. Toney, P.E., Materials Division Engineer
• AudienceoEspecially Those with Questions
Questions?Questions?