The asphalt pavement plant mixing hot recycling technology not only reduces the
consumption of natural resources by recycling discarded asphalt pavement, but
also effectively saves economic costs. However, the composition of recycled
asphalt pavement (RAP) materials exhibits significant variability, which hinders
the widespread use of RAP in recycled asphalt mixtures (RAM). To address this
issue, this article evaluated the variability of RAP with different rock types
and the addition of new aggregates and asphalt-aggregate ratios, and developed
intelligent software to determine the maximum allowable RAP content for
different road grades. At the same time, homogenization measures such as
classification and stacking of RAP should be taken to increase the RAP content.
The results show that Basalt RAP exhibits more significant variability in
grading and asphalt-aggregate ratio compared to Limestone RAP. Additionally, the
variability in RAP grading is greater than that in asphalt-aggregate ratio.
There is also some fluctuation in the ratio of newly added aggregates to
asphalt, with the fluctuation of new aggregates being greater than that of new
asphalt. The maximum RAP content determined by intelligent software is
controlled by the RAP asphalt-aggregate ratio, and due to the greater
variability of basalt RAP asphalt-aggregate ratio, its determined maximum
content is smaller than that in limestone RAP. In addition, the homogenization
treatment of RAP can reduce the coefficient of variation of the 4.75mm, 2.36mm,
and 0.075mm sieve size pass rates of RAM by 3.65%, 3.25%, and 3.31%,
respectively, while reducing the coefficient of variation of asphalt aggregate
ratio by 1.21%. Through this homogenization measure, the factory can produce RAM
with more stable gradation and asphalt aggregate ratio.