Developing QC/QA Specifications for Hot Mix Asphalt Concrete in Illinois

Abstract

The Illinois Department of Transportation (IDOT) has recently undertaken a quality management program to improve the quality of construction, allow more innovation, and reduce IDOTs management of industry construction programs. The Asphalt Concrete (AC) Quality Control/Quality Assurance (QC/QA) program is a significant part of this quality management program. IDOT accredits the success of the AC QC/QA program to gradual implementation and contractor and industry involvement. In 1991, four projects were constructed under a newly developed QC/QA specification. After reviewing and evaluating feedback from the contractors and IDOT personnel, the specification was revised for use on 1992 projects. In 1992, IDOT let 30 QC/QA projects, and in 1993, 65 QC/QA projects. In 1994 and 1995, most AC projects containing over 225 metric tons (250 tons) of hot-mix asphalt (HMA) were designated as QC/QA projects. In conjunction with this effort on AC quality, an aggregate certification program was implemented. The program ensures that aggregate gradation is highly controlled and is acceptable for incorporation into the mixture. Training programs for contractor QC and aggregate certification were also implemented. Analysis of the data indicates an increase in uniformity of the HMA, potentially leading to a 15 percent increase in fatigue life. IDOT is now examining the implications of developing end-result and performance-related specifications (ERS/PRS) for the AC QC/QA program. In the summer of 1996, one QC/QA project was shadowed and evaluated based on newly developed ERS/PRS.