As is well known, sand and stone used in concrete require good gradation in order to obtain smaller porosity and a strong skeleton, thereby improving the technical performance of concrete and saving costs.
Many technicians emphasize the grading of sand and stone separately, while neglecting the overall grading of sand and stone mixtures.
In fact, considering the economy and volume stability of concrete, a small amount of cementitious material slurry is needed to fill as many gaps as possible between coarse and fine aggregate particles and bond them together.
This means that the aggregate should have a continuous distribution of particle groups from sand to gravel to reduce the gaps after mixing.
That is, in addition to considering the individual gradation of coarse and fine aggregates, concrete should also consider the overall gradation of coarse and fine aggregates.
The basic idea of calculating sand ratio using the overall grading method of sand and gravel is that the overall grading of the sand and gravel mixture is best when the bulk density of the sand and gravel mixture is at its maximum.
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