Date: February 1999

LTPPBind Simplifies Superpave Binder Selection

With the introduction of the Federal Highway Administration's (FHWA) new LTPPBind software, selecting the correct performance graded (PG) binder to use when implementing the Superpave mix design system has just become much easier. The PG binder system classifies binders based on their suitability for a range of pavement temperatures. The LTPPBind software is a tool for pavement engineers to use in selecting the most appropriate PG binder grade for a specific location, based on climatic data.

The program contains climatic data from 7,928 weather stations in the United States and Canada. The data includes listings of the minimum, mean, and maximum temperatures for these locations, as well as such information as the average number of days with temperatures over 30 °C (86 °F). Users can zoom in on a particular region and receive a summary of temperature data and PG binder calculations for the three weather stations closest to the selected location on the map.

LTPPBind is an enhanced, more user-friendly version of the SHRPBind software that was developed by the long-term pavement performance program (LTPP) based on work done under the Strategic Highway Research Program (SHRP). The modifications include updating the temperature database to include temperature data through 1996, as well as improving the pavement temperature models. The program also provides several methods of adjusting the PG binder grade for different levels of traffic loads and speed.

The software is designed for use by highway agencies and contractors, as well as suppliers. Ala Mohseni of Pavement Systems, LLC, which developed the program under an FHWA contract, recently demonstrated the software in Idaho to a group of agency and industry staff and says that "people were surprised at how easy it is to use. It only takes two clicks of the mouse to get what you want."

Copies of the software can be obtained from the LTPP Web site at www.tfhrc.gov/. From the home page, select "LTPP" and then "Products."

A second version of LTPPBind, which will incorporate minor changes, is already in the works. The new version will be released on CD-ROM and on the Internet this spring.

For more information, contact the LTPP customer service line at 423-481-2967 (email ltppinfo@fhwa.dot.gov), or Ala Mohseni at Pavement Systems, LLC, email: amohseni@erols.com.

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