Three indexes to characterise crushing and screening of reclaimed asphalt pavement

Abstract

The more reclaimed asphalt pavement (RAP) is used in asphalt production, the more properties of the pavement depend on the characteristics of the RAP. Crushing and sieving of RAP into different fractions are the most used means of RAP processing that can allow ensuring consistency and the desired properties of the produced mixture. Currently, however, there is no method to compare different RAP processing methods. Here we propose three indexes to evaluate crushing and screening of RAP – Chunk index, Breakdown index, and Filler increase index (CBF indexes). These indexes are derived from the black and white grading curves of RAP and, therefore, can be of practical use for asphalt producers. Through full-scale validation with four different crushers, we found that the indexes allow for a quantitative comparison of different RAP processing methods and can be used to optimise the configuration of a particular crusher. A calculation tool is attached to the paper.