Development and Refinement of the Florida Department of Transportation’s Percent Within Limits Hot Mix Asphalt Specification

In July 2002, the Florida Department of Transportation (FDOT) implemented a statistically based, percent within limits (PWL) specification for the acceptance and payment of hot mix asphalt. The Specification also addressed small quantities as well as single test pass/fail criteria. The same year FDOT also adopted a Contractor Quality Control (CQC) system where acceptance was based on the contractor’s quality control data. The PWL specification criteria were developed based on data collected from FDOT construction projects built under the previous Quality Assurance (QA) System, where acceptance and payment were based on tests conducted by FDOT personnel. In 2004, FDOT conducted a study to assess the PWL specifications after two years of use. The study was conducted to compare the variances generated under the old QA system to variances generated under the new CQC system. Data was collected from 79 recently completed CQC projects and analyzed. The analysis examined variances of various mixture characteristics, including roadway density, percent air voids, asphalt binder content, percent passing the No. 8 (2.36 mm) sieve, and percent passing the No. 200 (0.075 mm) sieve. The analysis also examined individual mixture characteristic pay factors and composite pay factors generated under the CQC System. FDOT concluded that, in general, the variances and pay factor system based on data from the old QA system reflected typical values identified under the new CQC system. Only a few of the PWL specification criteria needed slight modifications to better reflect current variances. Refinements were also made to the small quantity payment system as well as the pass/fail criteria for single test results.

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  • English

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  • Accession Number: 01041451
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 30 2007 1:29PM