Effect of testing variability on contractor payment for asphalt pavements

Acceptance of asphalt pavements on a lot basis depends on how well the material conforms to specified quality characteristics. If a lot does not fall within the specified tolerance limits for a given characteristic, the contractor payment for that lot may be adjusted according to a predetermined payment schedule. This study evaluated the effect on contractor payment of the variability of the test method. Payment factors based on selected state highway agency specifications, typical of the most commonly used types of acceptance plans, were estimated using simulation techniques. The results were illustrated by plotting the operating characteristics (OC) in terms of expected payment. The OC plots show that the contractor can receive reduced payment even when there is no material variability and the process mean is on target. This reduction was due to the relatively large magnitude of the testing variability as compared with the tolerance range specified in the simulated acceptance plans. The simulation routine developed to estimate contractor payment can, with suitable modifications, be used for any acceptance plan.