Let us design the SMA coarse aggregate fraction (particles larger than 2.0 mm). The majority of guidelines recommend its content should be about 70-80% (m/m) of the whole aggregate mix, making it the major component. It may seem that there is little room to maneuver; however, there is a huge potential for controlling the SMA properties by making changes within this narrow range.
Some issues are worth deliberating, namely the impact on a mix exerted by the following:
• A change in the content of coarse aggregates (grains retained on a 2 mm sieve)
• The actual gradation of the coarse aggregate fraction (distribution of coarse aggregate on sieves larger than 2 mm)
• The density of the coarse aggregate particles
To illustrate these issues, two model mixes of coarse aggregates, calculated in a laboratory, will be discussed. One point should be mentioned at the beginning. We will use the following sieve set for coarse fraction: 2.0 mm, 4.0 mm, 5.6 mm,
8.0 mm, 11.2 mm, and 16.0 mm.
