Resistance of large stone asphalt mixes to rutting

Rutting of hot mix asphalt pavements has increased in recent years because of number of heavy vehicles is increasing. The paper describes how the Use of Large Stone Asphalt Mixes (LSAMs) increases stability, shear resistance and the rutting resistance of Hot Mix Asphalt (HMA) pavements. LSAMs are defined as HMA paving mixtures that contain nominal maximum aggregate sizes between 25 and 63 mm. In this experimental work the Modified Marshall Mix design method according to ASTM-D5581 is used for the design of these mixtures. The rutting resistance of LSAM mixes were evaluated and compared to conventional HMA mixtures. Large Stone Asphalt mixes designed with four different gradations and were evaluated. The stone to stone contact of these mixtures was determined using dry rodded density test according to AASHTOT19. Rutting specimens were prepared at four asphalt contents for large stone asphalt mixes and at optimum asphalt content for a conventional mixture. The rut depth of specimens was obtained at 12000 loading cycles. The effect of various parameters such as asphalt content, air voids, gradation and stone to stone contact of large size aggregate on rutting resistance was evaluated using wheel tracking rutting tester.