Impact of Asphalt Mixture Specification Limits: A Theoretical Analysis

Specifications limits and tolerances are crucial in the relationships among contractor, road agency, and citizens because they influence profits, acceptance procedures, and pavement durability. They mainly depend on processes involved, and, unfortunately, their relationship with durability is mainly empirical and calls for further investigation. In the light of these issues, the study described in this paper deals with assessing how durability and pay adjustment (PA) are affected by variations in the main explanatory variables [e.g., air-void content (AV)] within specification limits. A model was set up in order to assess the impact on the modulus of a bituminous mixture, which is a crucial factor for the expected life (EXL). The model was applied to a well-known set of contract specifications in order to check for their suitability and rationale. Results demonstrate that usually, air void-related consequences are worse than penetration-related consequences, which, in turn, outrank aggregate gradation-related and asphalt content-related consequences. An exception is the maximum size of aggregates. Furthermore, when pay adjustments build on empirical algorithms, they have to be layer-specific because the same error implies more severe consequences in deeper layers. Results can benefit both researchers and practitioners. © 2020 American Society of Civil Engineers.