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Why are stone mastic asphalt used in heavily trafficked roads?

Why are stone mastic asphalt used in heavily trafficked roads?

Stone mastic asphalt (SMA) developed in Germany in late sixties. It is characterized by having a high proportion of coarse aggregates that interlock to form a strong aggregate skeleton. Typical SMA composition
consists of 70-80% coarse aggregates, 10% filler and 6% binder.

The concept of SMA design is that severe traffic loads is carried by the stone skeleton, and the mastic (a combination of fine aggregates, filler and binder) is introduced in the mix to fill out the remaining void spaces with an aim in achieving durability. To ensure that the course aggregate stone contact function, it is essential to prevent immediate sizes of aggregate to hold course aggregates apart.

Owing to high binder content, drainage inhibitor is added to prevent binder drainage during transport and placing.


In essence, SMA provides a textured, durable and rut resistant wearing course and hence they are commonly used in heavily trafficked roads with high traffic stress.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

One comment on "Why are stone mastic asphalt used in heavily trafficked roads?"

gopal says:

what are the standards for collection and testing for quantity and quality of ingredients used in a road work after construction

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