What Is Superpave 1vs6d

Superpave Hot Mix Asphalt What is Superpave? SUPERPAVE is the result of a $50 million research project conducted by the Strategic Highway Research Program (SHRP) of the Federal Highway istration between 1987 and 1993. This effort was undertaken to develop better tools for deg longer lasting asphalt pavements. The primary concerns were permanent deformation (e.g. rutting, fatigue cracking) and low temperature cracking. When SHRP completed its research, Superpave had developed into a system of three related components: ¾Performance Graded (PG) asphalt binder specifications ¾Volumetric mix design ¾Mix analysis performance prediction Perhaps the most important product of the Superpave research was the development of Performance Graded (PG) asphalt binders. This system classifies binders (asphalts) into grades based on their performance for pavement temperatures typically encountered. For example, a PG 64-22 binder will o o meet performance criteria at pavement temperatures as high as 64 C and as low as -22 C. Using the Superpave system, mix designers now select asphalt binders to suit the climate and traffic volumes for specific pavements. All Hot Mix Asphalt producers in New York State use PG binders for all of their production! Superpave’s volumetric mix design system balances aggregates, asphalt and voids with the ultimate goal of producing durable mixes that resist rutting. To do so, designers volumetrically proportion aggregates and PG asphalts, and then examine mix compaction using a Superpave gyratory compactor. The gyratory compactor is intended to help predict pavement performance by simulating the effect of traffic on asphalt pavement in the laboratory. At the same time, the compacted samples yield information about the volumetric properties of the mix – a strong predictor of on-grade performance. While the gyratory compactor is a key tool for predicting pavement performance, other test equipment and methods are under development. These tests, in combination with sophisticated modeling software, suggest that further improvements to the Superpave system will evolve over the coming years. Superpave is the NYSDOT Standard Mix Design NYSDOT considered dropping the Marshall Hot Mix Asphalt specifications from the 2002 Standard Specifications since they intend to only specify Superpave designs. Through a mutual agreement between the industry and DOT, the older mixes will be in the new specification, but only on a transitional basis. The mixes you’ve been ordering for years will ultimately be discontinued. Consequently, local governments need to learn more about Superpave and work toward the development of Superpave designs suited to local pavements. To this end, this is the first of a series of QUICK BITES information sheets intended to help the transition 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: 607-2558033). Part of the Cornell Local Roads Program’s QUICK BITES Information Sheets Co-produced by the New York State Department of Transportation (NYSDOT), Cornell Local Roads Program (CLRP) and New York Construction Materials Association (NYMaterials). QUICK BITES

JUNE 2002

CORNELL LOCAL ROADS PROGRAM

Superpave Hot Mix Asphalt

What is Superpave?

Sheets in this series include: 9What is Superpave? The background of Superpave hot mix asphalt (This QUICK BITE Sheet) Mix Definitions Explanation and examples of the terminology used to describe Superpave. 9Performance Graded Asphalt Binder The performance graded binder system used in Superpave and the PG grades used in New York State. ‰Traffic Levels vs. ESALs ESAL based traffic system for determining mix selection. 9Friction Explanation of the different friction demands and requirements of various levels of traffic. ‰Proper Mix Selection Comparison of Superpave mixes to those used the past. Tables will help with mix selection based on experience, traffic levels and location in the state. Explains why the higher traffic mix is not better when not needed. Truck Tickets and the Mix Codes Explains how to know what is in the truck when it arrives on site. ‰Tack coat Describes the importance of and proper use of tack coat. ‰Segregation Defines the problem of segregated mix and provide some solutions. ‰Tenderness Defines the problem of tenderness during construction and provides some solutions. ‰Compaction Explains the importance of good compaction and the different ways to monitor density. ‰ts Explain the importance of good t construction, t density and the use of the wedge t.

9 Sheets available Under development

QUICK BITES

JUNE 2002

‰ To be added

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