[Ivan_1966]

I bought a fraction of 3-5mm. I'm drying the sand now.
In test 2, the ratio of the two fractions is 50% of the volume of the test volume (1000 ml).
This is absolutely wrong. Also the ratio of 70% Vf (1-2mm) to 30% Vf(0.10-0.25mm) is wrong. We cannot thinking up arbitrary ratios. Even with calculation at 10 times the diameter difference between the small and large fraction - the volume ratio is 1000 times.


It is most appropriate to determine the ratio when mixing multiple fractions experimentally. We want to get the highest coefficent of packing.
So, for me, the correct method is the following:


The test volume is 1000 ml.
1. Fill the container with 1000 ml of the coarsest fraction.
2. We start adding small portions from the next finer fraction (recording their volumes) and stirring, mixing, vibrating etc. The fine fraction particles are inserted between the voids of the coarse particles. The volume of 1000 ml should remain unchanged (constant). We fill and vibrate until we can no longer keep the volume of 1000ml constant and it starts to increase.
This means that there is no more space (voids) between the coarse particles. We calculate the recorded quantities (volumes) of the fine fraction inserted and thus calculate the volume ratio.
3. If there is a third fraction - proceed as in point 2. Keep the total (mixed volume) constant - 1000 ml.