An optimum variant should be selected out of the three defined trial design gradation curves. The selection criteria of the optimal gradation curve should consist of the smallest amount of coarse aggregate combined with the following two conditions at the same time:
• VCAMIX is lower than VCAdrc or the VCA ratio (VCAmix/VCAdrc) is less than 1.0.
• VMA is higher than 17.0% (v/v) (usually minimum values of 17.5-18.0%).
If the VCAMIX is higher than the VCAdrc, the creation of a skeleton is not guaranteed. It can be changed by increasing the amount of particles bigger than the BP sieve—that is, increasing the amount of aggregates retained on the BP sieve should increase the VCAdrc. So sometimes additional trial gradations must be analyzed before finding an optimal solution.
Using this method, only one mix is eventually left. The monitoring of the skeleton and aggregate structure is behind us. Now it is time for the binder.
