Number of design gyrations for 100 mm compacted asphalt mixtures modified with polypropylene

Abstract

There is no standard accepted by highway authorities on the compaction procedures of 100 mm diameter gyratory compactor specimens. In previous studies on gyratory compaction, the utilisation of either coring from 150 mm specimens or preparing taller specimens than the usual 63.5 mm long Marshall specimens has been undertaken. The utilisation of 150 mm mould sizes introduces an important amount of mechanical disturbance during the coring process of 100 mm diameter specimens out of them. The novelty of the present study is that a new standard for preparing gyratory compactor specimens with a diameter of 100 mm and length of approximately 63.5 mm by utilising polypropylene fibers of 3 mm multifilament for the modification has been proposed for the first time. To achieve optimal conditions, in addition to gyratory compaction, modified bitumen samples’ physical properties, especially rotational viscosities, were also investigated in a detailed manner. Physical and mechanical tests have been carried out using the specimens prepared by changing the main testing parameter of gyration number from 30 to 70. The design gyration number of 100 mm polypropylene fiber reinforced dense bituminous mixtures has been determined as 33 under medium traffic conditions.