Development of the Florida Department of Transportation's Percent within Limits Hot-Mix Asphalt Specification

The Florida Department of Transportation adopted a percent within limits approach in July 2002 for the acceptance and payment of all hot-mix asphalt. Contractor test data, after being verified by the department, are used to calculate payment. Acceptance and payment for dense-graded Superpave^® mixtures are based on the following five asphalt material properties: roadway density, percent air voids, asphalt binder content, percent passing the No. 8 sieve, and percent passing the No. 200 sieve. Acceptance and payment for open-graded friction course mixtures are based on the following four asphalt material properties: asphalt binder content, percent passing the 3/8-in. sieve, percent passing the No. 4 sieve, and percent passing the No. 8 sieve. Contractor test data from recently completed construction projects were used to develop representative standard deviations of the asphalt material properties used for payment and acceptance. These standard deviations were then used to develop tolerance values for the percent within limits system. A system has been developed to handle acceptance and payment of small quantity LOTs (two or fewer sublots) within the same specification. In lieu of the department sampling and testing numerous independent samples and performing F-and t-tests to validate the contractor's results, an alternative verification and resolution system has been developed.