looking for the above, I have found a couple of nomographs that might allow me to intrpolate the answer, but I am not familiar with their use. I was hoping for a table from a DOT design manual, however my home state doesnt recognize CBR.
Limerock is used extensively in Florida and is designed and tested using the LBR instead of CBR. In general, LBR 100 equals CBR 80.
The Florida DOT Flexible Pavment Design Manual, Table 5.4, indicates that the structural number for LBR 100 limerock material is 0.18.
If you google "FDOT Flexible Pavment Design Manual", it should come up and is a free download.