Stone mastic asphalt

SMA has found use in Europe, Australia, the United States, and Canada as a durable asphalt surfacing option for residential streets and highways.

SMA has a high coarse aggregate content that interlocks to form a stone skeleton that resists permanent deformation.

The deformation resistant capacity of SMA stems from a coarse stone skeleton providing more stone-on-stone contact than with conventional dense graded asphalt (DGA) mixes (see above picture).

In the US, detailed mix design guidelines have been developed for SMA and published by the US National Asphalt Pavement Association in their Quality Improvement Publication QIP 122 as given in the references.

In batch plants, the fibre additive is added direct to the pugmill using individually wrapped press packs or bulk dispensing equipment.

Achieving high standards of compacted density and low field air voids has been identified as an important factor in the performance of all SMA work.