Aggregates hold water. This can be especially true with Limestone aggregates. Limestone can be very porous and can therefore absorb water. The absorbsion of stone and other aggregates can have a profound effect on mix consistentsy and product quality.
I am not sure if there is a 100% sure way to calculate you material absorbsion rate unless you are testing you materials (by saturating and weighing, then cooking out the moisture and re-weighing the materials) a couple times per day. You would also need to know the current moisture level in you materials as well, to know how much more water the will absorb. And total absorbsion is what we are concerned about.
If a mix design calls for and certain amount of stone, it is critical to know the moisture content of that stone , because water can add weight to material with out having an effect on volume. If you are meassuring you mix with a weigh belt, this could cause issues.
One issue would be that you will be likely to put a higher volume of material on the belt when it is bone dry than when the material is saturated. Another is that the dryer the material is the more moisture it will want to remove from the mix. so the dryer tit is the more you will likely add and the more water it will absorb.
If you you spray you materials to keep them at (SSD) Saturated Surface Dry, you will then be able to controls your batch consistency and product quality to a much higher degree. Saturated stone will have a consitent weight and will not try to absorb water from the mix.
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