The Percentage of Fine Aggregate may be entered on a Mix Design Form, provided the Specify Proportion of Fine Aggregate Tick Box has been ticked.
The Percentage of Fine Aggregate is the quantity of fine aggregate in the mix expressed as a percentage of the total aggregate content. If the Specify Proportion of Fine Aggregate Tick Box is not ticked, Firstmix calculates the percentage using the DOE Method.
The proportion of fine aggregate has a major influence on the workability of a mix. It also affects the cohesiveness of the mix.
You may wish to set your own value for the Percentage of Fine Aggregate if a particularly cohesive mix is needed or if trial mixes show that the mix quantities need to be modified to give the required workability.
If the Percentage of Fine Aggregate is specified, the Grading of Fine Aggregate, which according to the DOE Method would provide the required workability for the specified the Percentage of Fine Aggregate and the Free Water Content of the mix, is calculated and displayed on the Mix Design Form.
Since the percentage of fine aggregate influences the workability, it is the volumetric percentage that is significant. For lightweight concrete Firstmix therefore uses the volumetric percentage of fine aggregate in calculations, which concern workability. However for concrete made with normal weight aggregate Firstmix follows the DOE Method and uses the percentage of fine aggregate by weight, which in fact for normal weight aggregates will generally be close to the volumetric percentage, in all calculations.
Range: 10 - 80 %