Upgrading the Asphaltic Concrete Specification of the New Jersey Department of Transportation

Abstract

An earlier upgrading of New Jersey’s specification for in-place air voids in asphaltic concrete pavement was made to strengthen the acceptance procedure and incorporate several advances in specification-writing technology. Modifications included changing to percent defective as the quality measure, switching to an equation-type pay schedule, adding a bonus provision for superior work, and including a remove-and-replace clause for seriously defective work. Changing from an acceptance procedure based on the sample mean to one based on percent defective essentially redefined the acceptable quality level from a percent defective value of 50 to a considerably more demanding value of 10. To allow the construction industry a chance to become familiar with this new requirement, a relaxed form of the pay schedule was initially adopted. Industry has subsequently had extensive experience with the new specification and the New Jersey Department of Transportation is now preparing to modify the specification further to provide an even stronger incentive to produce high-quality pavement. The modifications were developed by a joint task force representing the construction industry and the New Jersey Department of Transportation and include increasing the bonus provision, retaining the present pay schedule for quality that is only marginally deficient, changing to a more steeply descending pay schedule for seriously defective quality, and adding a more elaborate retest procedure to ensure that substantial pay reductions, when they occur, are truly warranted. In addition to controlling air voids, the new acceptance procedure also combines requirements for thickness and smoothness into a single composite pay equation. Operating characteristic curves are presented to demonstrate the capability of the new procedure.