See my answer above for crushing. If you're putting more than 20-percent RAP back into HMA or WMA, then sizing RAP into two sizes is optimal. This helps control segregation and, therefore you have better control on air voids in the mix design. Typically, two sizes around Vi" ? 1A" and Vi' ? 0 works best for increasing RAP usage. A high frequency screening device would be preferred due to finer material separations.