PROCEDURE FOR ESTABLISHING A CORRECTION FACTOR FOR Gmb
The procedure used for establishing a correction factor is as follows:
1. Obtain one sample of sufficient plant produced material for 12 Gmb specimens and split per IM 357 into 6 specimens each between the contractor and engineer. This should provide enough material that 6 gyratory specimens may be compacted at both labs. The sample should be representative, but sampling procedure IM 322 is not required.
2. The material must be handled and compacted in the same manner by the contractor and engineer (hot-to-hot or cold-to-cold).
3. Compact the specimens per IM 325G.
4. Perform density testing on the compacted specimens per IM 321.
5. Average the 6 Gmb results for each lab.
The difference between the average Gmb results from the two labs will be considered the correction factor. NOTE: Unless otherwise decided on by the Engineer, only 1 correction factor will be established for a given mix design.
The engineer may use the results of 3 consecutive QC/QA split tests in lieu of a single 12 split sample. There can be no significant change to the mix between the 3 tests and no adjustments to the gyratory compactors. The material must be handled and compacted in the same manner by the contractor and engineer (hot-to-hot or cold-to-cold). The contractor’s QC results will be averaged and the engineer’s QA results will be averaged with the difference being the correction factor to be applied.