Components of variability in bituminous concrete pavement construction Volume I - Summary of current state practices (FHWA-OK-92-07) 2179

Abstract

The Oklahoma Department of Transportation (ODOT) turned to quality assurance specifications in 1989 after several years of careful study and consideration. The objective of phase-I of this research project was to evaluate the ODOT's Quality Assurance Specifications (QAS) for bituminous concrete pavements in comparison with those developed by other states. To meet the objectives of this phase, a survey of practice was conducted in Fall 1990. A letter was mailed to state DOTs asking whether the agency is using statistically‡based QAS for bituminous concrete pavement construction, and if so, the letter requested copies of the specifications. Of the 30 state DOTs which responded to the survey, 70% had statistically-based QAS, 17% reported the use of combination of method specifications and QAS, and 13% were in the process of developing QAS or planning to develop one. High levels of satisfaction with, and confidence in, QAS were expressed by many of the agencies which used them. Results of the survey indicated that there was a wide variation among specifying agencies in the quality attributes used for acceptance purposes, definition of lot and sublot of bituminous pavement, decision rule for acceptance, allowable tolerances for acceptable construction, and the basis for payment. For acceptance purposes, the three most often used quality attributes were aggregate gradation, asphalt content. and in-place density. The two most common decision rules for acceptance were the percent within limits method and the average deviation method. The methods used to detennine the payment for a lot of construction material varied significantly among the different agencies.