STANDARDS FOR AGGREGATES

Aggregates and test methods. These new Standards will change the way in which we look at our aggregates, although the materials will be the same there is a new way of defining aggregate sizes, different sieve sizes with new grading and a new set of tests for physical and mechanical properties.

AGGREGATE SIZE (d/D)

Sizes are now described using two sieves a lower sized sieve (“d”) and a higher size sieve (“D”) and is now classed as d/D, an old 20mm single size stone will now be classed as 10/20 e.g. “d” equals a 10mm sieve and “D” equals a 20mm sieve. For all-in aggregates “d” is 0.

GRADING CATEGORY (Gc)

There is now a Grading Category (Gc) which specifies the percentage of material passing d/D, therefore a 10/20 would have a grading category Gc85/20 this means that up to 85% of the material can pass the 20mm sieve (D) and up to 20% can pass the 10mm sieve (d).

The grading for a 10/20 Gc85/20 would be

FLAKINESS (FI)

The Flakiness test has changed you now use a bar sieve along with the new sieve sizes, the results are lower then the old method and for Asphalts a Flakiness of less then 35 is now acceptable FI35.