The Americans have undertaken analyses on the usefulness of various methods of testing for contact between coarse particles. Ultimately, they have settled on the dry — rodded test according to AASHTO T 19-00 (Brown and Haddock, 1997). It has also been standardized as ASTM C29-97.
Let us remember what we are considering now; we are looking for the content of air voids among the compacted coarse particles that make a skeleton. Thus we are screening the coarse aggregate (regarded as the active fraction) of each of three trial aggregate mixes (three design gradation curves of Stage 2) through the boundary sieve (BP sieve) selected in accordance with the NMAS. Furthermore, three such screened samples of the coarse aggregate will be tested according to the dry-rodded method.
What does the dry-rodded method involve? All in all, it consists of compacting the coarse aggregate and determining the air voids among the particles. As a result, dry-rodded testing provides the percentage of air voids in a compacted skeleton of coarse aggregate denoted as VCAdrc. It should be remembered that Volume of coarse Aggregate-Dry Rodded condition (VCAdrc) has been determined for the part of an aggregate mix that is larger than the BP sieve for the size of SMA being designed.
And now the first stage of control in creating the skeleton is behind us.
