Aggregates for Asphalts

Dense limestones are widely used in asphalts (also called bituminous macadam). The properties which determine the suitability of an aggregate are its  

The requirements for aggregate in asphalts vary widely and depend on the application [8.1]. 

In the UK, BS 63 specifies limits for grading and flakiness index for eight single-sized grades (50, 40, 28, 20,14,10, 6 and 3 mm). These are blended to give the required particle size distribution as specified in [8.19, 8.20]. 

The Highways Agency s Specification 1991 [8.7] identifies strength, durability and cleanliness as being important factors, but places the responsibility on the specifying engineer to assess the requirements for a particular application. A CEN Standard is in preparation (section 8.8.1). 

Porous limestones are seldom used because they have a high bitumen demand, which increases cost. 

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