Quality Control and Acceptance of Recycled Hot-Mix Asphalt Mixtures

Drum mix plants are the primary hot-mix asphalt (HMA) production methods. In these plants, a totalizer controls the input rate of virgin aggregates and reclaimed asphalt pavement (RAP) materials. A detailed analysis of the totalizer, mass balance approach, and mixture production data by the Kansas Department of Transportation from several projects showed that the estimated RAP quantity based on total mix production data was higher than the maximum allowable value. To verify that finding, this study collected operation and mixture production data from several HMA plants on multiple days to calculate the RAP feed rate/quantity and build control charts for the quality control and acceptance process. The mixture production input and output data analysis identified the RAP binder content as the critical parameter in determining the RAP quantity in the produced HMA. This finding was also confirmed in the statistical analysis and Monte Carlo simulation.