Adjusted Fine Aggregate Density

If results are entered on the Trial Mix Dialog, FirstMix calculates an Adjusted Fine Aggregate Density and an Adjusted Coarse Aggregate Density from the Trial Mix results.

It is assumed that the following items of the mix are as specified in the original mix design:

• Cement content (weight) and density.
• Pozzolan content (weight) and density.
• Fine aggregate content (weight).
• Coarse aggregate content (weight).

It is also assumed that the following items have been correctly measured in the trial mix:

• Air Content (percent by volume).
• Water Content.

Firstmix then calculates the adjusted fine and coarse aggregate densities, which would give the measured concrete density for these assumptions.

The trial mix volume is obtained by dividing the sum of the weights of the mix constituents by the measured concrete density. The volumes of the water, cement and pozzolan (if used) are obtained by dividing their weights by their densities; these volumes together with the measured air content are subtracted from the trial mix volume to obtain the combined volume of fine and coarse aggregate. The adjusted overall aggregate density is found by dividing the combined aggregate weight by the combined aggregate volume. Finally the fine and coarse aggregate densities used in the original mix design are factored by the ratio of the adjusted overall aggregate density to the overall aggregate density used in the original mix design.

If the Trial Mix results are used in a mix design the Relative Aggregate Density is calculated on the basis of the adjusted fine and coarse aggregate densities.