Summary
Aggregate Grading - is a measure of how well distributed the sizes of the particles in an aggregate are. A well graded aggregate will have a good range of particle sizes and will have a fair representation from every size of particle.
Technical Information

The grading of an aggregate can be measured by what proportion of the aggregate, by mass, passes through different sized sieves.
The grading of an aggregate can be altered by blending multiple aggregates of different gradings.
For coarse aggregate the following statements are true:
- A smaller aggregate size requires a larger amount of paste because there is more surface area to cover per volume of aggregate.
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A lower volume of paste can be used whilst still achieving the same compressive strength if the maximum aggregate size is increased.
- There is a limit for the reduction of paste volume by increasing maximum aggregate size, depending on the required strength of the concrete. If the concrete is required to be stronger, the most economical maximum particle size will be smaller.
For fine aggregate, the following statements are true:
- If the fine aggregate is too coarse, harshness, bleeding and segregation may occur.
- If the fine aggregate is too fine, the mix will require additional water and segregation may occur.
- If the grading varies significantly, the workability of the fresh concrete will likely suffer as a result.
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