Owing to the porous nature of friction course, its deterioration rate is faster than conventional bituminous materials and the durability of friction course is a main concern form users. The service life of friction course is reported to be around 8-10 years.
The main durability problem of friction course is associated with raveling of friction course and stripping of underlying layers. Raveling of friction course occurs as a result of lack of cohesion between aggregates. Stripping of underlying layers is attributed by inadequate drainage of water through the friction course. With the use of polymer in friction course, it permits the use of higher air void (allows for better drainage) and higher binder content.
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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