Summing up:
• When designing an SMA mixture, one should not decrease the content of filler below a minimum value (defined by using a 0.063-mm sieve in
Europe or a 0.075-mm sieve in the United States). The lack of filler will be reflected in a decrease in the durability of the mix and the void content and an increase in the risk of the appearance of fat spots.
• An increased amount of filler causes higher viscosity of the mortar, which promotes resistance to deformation. But one should not use an excessive amount of filler because it is easy to overstiffen the mortar, which can lead to cracking.
• Too fine a filler can cause problems since it absorbs much of the binder and may plasticize the mix.
• It is worthwhile to take note of Rigden’s test results, particularly when changing filler in the same mixture during continuous production. A new filler with a decidedly different void content than the former one may result in unwanted surprises.
• Adding hydrated lime at a rate of about 1.0-1.5% is a good move as doing so improves the binder-aggregate adhesion and boosts resistance to water damage.
