Stone mastic asphalt (SMA), also called
stone-matrix asphalt, was developed in Germany in the 1960s. It provides a deformation resistant, durable surfacing material, suitable for heavily trafficked roads. 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 stone skeleton is filled with a
mastic of
bitumen and
filler to which
fibres are added to provide adequate stability of bitumen and to prevent drainage of binder during transport and placement. Typical SMA composition consists of 70-80% coarse aggregate, 8-12% filler, 6.0-7.0% binder, and 0.3 per cent fibre.