8/8/2019 What is Superpave

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Superpave Hot Mix AsphaltWhat is Superpave?

Part of the Cornell Local Roads Programs QUICKBITESInformation SheetsCo-produced by the New York State Department of Transportation (NYSDOT),Cornell Local Roads Program (CLRP)

and New York Construction Materials Association (NYMaterials).

QUICKBITES JUNE 2002 CORNELL LOCAL ROADS PROGRAM

SSSSUPERPAVEUPERPAVEUPERPAVEUPERPAVE is the result of a $50 million research project conducted by the Strategic HighwayResearch Program (SHRP) of the Federal Highway Administration between 1987 and 1993. Thiseffort was undertaken to develop better tools for designing longer lasting asphalt pavements. Theprimary concerns were permanent deformation (e.g. rutting, fatigue cracking) and low temperaturecracking. When SHRP completed its research, Superpave had developed into a system of threerelated components:

Performance Graded (PG) asphalt binder specificationsVolumetric mix designMix analysis performance prediction

Perhaps the most important product of the Superpave research was the development of PerformanceGraded (PG) asphalt binders. This system classifies binders (asphalts) into grades based on theirperformance for pavement temperatures typically encountered. For example, a PG 64-22 binder willmeet performance criteria at pavement temperatures as high as 64

oC and as low as -22

oC. Using

the Superpave system, mix designers now select asphalt binders to suit the climate and traffic

volumes for specific pavements. AllAllAllAll Hot Mix Asphalt producers in New York State use PG bindersfor all of their production!

Superpaves volumetric mix design system balances aggregates, asphalt and voids with the ultimategoal of producing durable mixes that resist rutting. To do so, designers volumetrically proportionaggregates and PG asphalts, and then examine mix compaction using a Superpave gyratorycompactor. The gyratory compactor is intended to help predict pavement performance bysimulating the effect of traffic on asphalt pavement in the laboratory. At the same time, thecompacted samples yield information about the volumetric properties of the mix a strong predictorof on-grade performance.

While the gyratory compactor is a key tool for predicting pavement performance, other testequipment and methods are under development. These tests, in combination with sophisticatedmodeling software, suggest that further improvements to the Superpave system will evolve over thecoming years.

SuperpaveSuperpaveSuperpaveSuperpave isisisis the NYSDOT Standard Mix Designthe NYSDOT Standard Mix Designthe NYSDOT Standard Mix Designthe NYSDOT Standard Mix Design

NYSDOT considered dropping the Marshall Hot Mix Asphalt specifications from the 2002Standard Specifications since they intend to only specify Superpave designs. Through a mutualagreement between the industry and DOT, the older mixes will be in the new specification, but onlyon a transitional basis. The mixes youve been ordering for years will ultimately be discontinued.Consequently, local governments need to learn more about Superpave and work toward thedevelopment of Superpave designs suited to local pavements.

To this end, this is the first of a series ofQUICKBITESinformation sheets intended to help thetransition from Marshall to Superpave. The sheets will be placed on the CLRP web site(www.clrp.cornell.edu) and are available from the Cornell Local Roads Program (phone: 607-255-8033).

http://www.dot.state.ny.us/http://www.dot.state.ny.us/http://www.clrp.cornell.edu/http://www.clrp.cornell.edu/TechAssistance/tipSheets.htmhttp://www.clrp.cornell.edu/TechAssistance/tipSheets.htmhttp://www.clrp.cornell.edu/TechAssistance/tipSheets.htmhttp://www.clrp.cornell.edu/TechAssistance/tipSheets.htmhttp://www.clrp.cornell.edu/TechAssistance/tipSheets.htmhttp://www.clrp.cornell.edu/TechAssistance/tipSheets.htmhttp://www.clrp.cornell.edu/http://www.clrp.cornell.edu/http://www.clrp.cornell.edu/http://www.dot.state.ny.us/http://www.clrp.cornell.edu/http://www.dot.state.ny.us/http://www.clrp.cornell.edu/http://www.clrp.cornell.edu/TechAssistance/tipSheets.htm

8/8/2019 What is Superpave

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Superpave Hot Mix Asphalt What is Superpave?

QUICKBITES JUNE 2002 PAGE 2 of 2

Sheets in this series include:Sheets in this series include:Sheets in this series include:Sheets in this series include:

What is Superpave?What is Superpave?What is Superpave?What is Superpave?The background of Superpave hot mix asphalt (This QUICKBITESheet)

Mix DefinitionsMix DefinitionsMix DefinitionsMix DefinitionsExplanation and examples of the terminology used to describe Superpave.

Performance GradedPerformance GradedPerformance GradedPerformance Graded AsphaltAsphaltAsphaltAsphalt BinderBinderBinderBinderThe performance graded binder system used in Superpave and the PG grades used in New YorkState.

Traffic Levels vs. ESALsTraffic Levels vs. ESALsTraffic Levels vs. ESALsTraffic Levels vs. ESALsESAL based traffic system for determining mix selection.

FrictionFrictionFrictionFrictionExplanation of the different friction demands and requirements of various levels of traffic.

Proper Mix SelectionProper Mix SelectionProper Mix SelectionProper Mix SelectionComparison of Superpave mixes to those used the past. Tables will help with mix selectionbased on experience, traffic levels and location in the state. Explains why the higher traffic mix isnotnotnotnot better when not needed.

Truck Tickets and the Mix CodesTruck Tickets and the Mix CodesTruck Tickets and the Mix CodesTruck Tickets and the Mix CodesExplains how to know what is in the truck when it arrives on site.

Tack coatTack coatTack coatTack coatDescribes the importance of and proper use of tack coat.

SegregationSegregationSegregationSegregationDefines the problem of segregated mix and provide some solutions.

TendernessTendernessTendernessTendernessDefines the problem of tenderness during construction and provides some solutions.

CompactionCompactionCompactionCompactionExplains the importance of good compaction and the different ways to monitor density.

JointsJointsJointsJoints

Explain the importance of good joint construction, joint density and the use of the wedge joint.

Sheets available Under development To be added

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