The importance of mineral filler on construction specifications

Studies have been conducted to date to demonstrate how the dust content in hot-mix-asphalt (HMA) should be accounted for in construction specifications. It may be detrimental to pavement performance if a high change in the dust content from the actual target value is not captured during HMA production. A study was conducted to determine whether the present composite pay factor (CPF) in Florida reflects the laboratory predicted loss in cracking performance. Resilient modulus, creep and strength tests, along with the University of Florida fracture mechanics model were used on 18 Superpave mixtures. Based on the analysis conducted, it was found that the current CPF in Florida did not reflect the expected loss in performance. The results showed that a 2% increase in dust can be at least as or more detrimental than 0.7% reduction in the asphalt content. However, this was not reflected in the weighted factor assigned to dust in the CPF equation. In this research, a framework to identify performance-based acceptance procedures was also presented. Ideally, this framework can be used to develop or modify construction specifications so that the expected performance of HMA can be assessed accordingly.