SMA owes its fast and wide-spreading growth to some unquestionable merits such as the following:
• Long working lifetime (service life)
• High resistance to deformation due to the high-coarse aggregate content and strong skeleton of interlocked aggregate particles
• Increased fatigue life as a result of the higher content of binder
• Increased in-service traffic wear resistance because of the presence of hard coarse aggregate grains,
• Good macrotexture of the layer surface and decreased water spray generated by traffic on wet surfaces
• Good noise-reduction properties
However, despite its strong points, the following drawbacks also exist:
• Low initial skid resistance unless a fine aggregate gritting or a crushed sand finish is applied
• High cost of the mix compared with a conventional asphalt concrete (initial costs can be increased by 10-20% due to higher contents of binder, filler, and stabilizer, but the extended service life of the pavement can result in reduced life cycle costs)
• Risk of different types of fat spots appearing on the surface as a result of errors or variability during SMA design, production, or construction
To end this part of the discussion, let us recall the words of Dr. Zichner of his patent:
All in all, the method taught by the invention and the procedures made possible thereby
provide a wear surfacing characterized by high resistance to abrasion, long-lasting
roughness, and reliable adhesion to the road surface. (Zichner, 1971).
