LTPP Team Approves Materials
Characterization Procedures
Getting more accurate and repeatable resilient modulus data is becoming increasingly important because under Superpave guidelines, resilient modulus is used for evaluating pavements. Experts in the Long Term Pavement Performance (LTPP) program developed some procedures to obtain better quality data for resilient modulus using either laboratory testing or back calculation from nondestructive deflection testing with a falling weight deflectometer (FWD).To improve laboratory resilient modulus testing, the LTPP program developed and documented LTPP Materials Characterization Program: Resilient Modulus of Unbound Materials (LTPP Protocol P46) Laboratory Startup and Quality Control Procedure. This procedure allows LTPP contractors to produce repeatable test results using a check of the electronic and mechanical components of the test equipment as well as the technicians' proficiency. The Alabama and Kansas DOTs are now implementing these procedures. In addition, FHWA will develop technical videos and a pictorial manual to aid users in implementing and continuing to use these procedures.
To improve the back calculation method, the FWD must be properly operated and calibrated to produce accurate results that can be used with confidence. For FWD use, the LTPP program developed calibration procedures, centers, and software. The program also developed an LTPP FWD testing manual, temperature adjustment procedure, and software for data quality control. These products will be further modified to read the AASHTO DDX file format which can be used to collect deflection data. The modifications of the software and procedures as well as calibration procedure videos will be presented in a workshop format to train the user in their application.
-- Max Grogg, (518) 431-4224.
Superpave Finds a Home in Charm City
Albert Hinojosa, FHWA MD Division, Bill Flanigan, more. Bill Flanigan, contractor, George Balog, Baltimore Department of Public Vice Chairman of Works, Jitesh Parikh, FHWA MD Division, and Thomas Baltimore-based Harmen, FHWA OTA, got together to talk about Superpave. Word is spreading fast about the benefits of Superpave asphalt mix technology. FHWA and State DOTs are promoting the Superpave system for asphalt binder selection and mix design, which was developed by the Strategic Highway Research Program (SHRP). But when contractors start singing the praises of the new technology to their local customers, you know that Superpave is well on its way to becoming the new standard.
Those praises were sung recently by a contractor in Baltimore. Bill Flanigan, Vice Chairman of Baltimore-based general contractor P. Flanigan & Sons, set up a meeting with George Balog, Director of Public Works for Baltimore, to talk about this "Superpave." On Friday, April 18, Bill Flanigan, along with representatives from FHWA, Maryland State Highway Administration, and the Maryland Asphalt Association, presented Superpave to George Balog and his staff at the City of Baltimore's Public Works. Questions were asked. And discussions were held. In the end, Bill asked George what he thought about this Superpave. George responded, "Superpave looks like it could be an improvement over present asphalt specifications. Its use could address citizen's concerns with 'rough surfaces' and may reduce vibrations on adjacent properties caused by truck traffic."
The Maryland State Highway Administration is a national leader in the implementation of this new technology and plans to be fully implementing Superpave by the year 1999. And now through this meeting, the City of Baltimore is also a leader. They will be one of the first cities in the country to utilize this new technology.
-- Thomas Harman, (202) 366-0859.
