14 What are the three requirements for the best grading of a

14. What are the three requirements for the best grading of aggregations?

Solution

For a well graded aggregate, it should contain all the particle sizes so that the voids between the aggregates will get filled with small sized aggregates. It will result in a dense,strong mix moreover volume of free cement paste is available in this case for lubrication resulting in higher workability. It should not contain flaky or elongated aggregates. Mostly prefered aggregates for strength is angular aggregates(more surface is available because of the angular shape) and for workability it is round(less surface area and there will be more availability of cement paste and so more lubrication). Texture of aggregate for better strength should be rough(interparticle bonding) and for better workabilty smooth textured(lesser surface area to be lubricated). There should not be missing sizes of aggregates while grading since it will result in gap gradaton and also avoid uniform size since it will result uniformily graded aggregate. Both will results in poor gradation