INFLUENCE OF RECYCLING AGENT TYPE ON RESILIENT MODULES AND RUTTING RESISTANCE OF ASPHALT CONCRETE PAVEMENT

Roller compacted asphalt concrete slab samples with dimension of(300x400) mm, 60 mm thick were prepared in the laboratory undercontrolled conditions. Forty-eight core specimens with diameter of 100mmand 60mm thick have been obtained from Roller compacted slabs, and wereimplemented for resilient modulus (Mr) and rutting resistance determinationunder indirect tensile repeated loading (ITRL), with constant stress level.Half of the cores were directly tested at 25° C and 40° C (unconditioned).The other half of cores were conditioned by placing in volumetric flask4000-ml filled with water at room temperature of 25˚C, then a vacuum of(3.74 kPa) was applied for 10 minutes to obtain 80 % degree level ofsaturation. The specimens were then placed in deep freeze at (-18˚C) for(16) hours. The frozen specimens were then moved to a water bath for (24)hours at (60ºC). Then they were placed in a water bath at (25ºC) or 40 ºC for1 hour, and they were tested for ITRL (conditioned). It was concluded thatthe change in permanent deformation at Conditioned test as compared tounconditioned test was ( 88.19%, 88.01% and 108.09% ) at 25˚C, while at40˚C it was ( 20.89%, -1.14% and 19.46%) for recycled mixtures with SoftAsphalt cement (Ac), (Soft Ac + Silica Fumes) and (Soft Ac+ Fly ash)respectively. The reduction in (Mr) at Conditioned test as compared toUnconditioned test was (-3.7%, -16.67% and -7.69%) at 25˚C, while at40˚C, it was (-6.25%, -14.29% and -7.14%) for recycled mixtures with (SoftAc), (Soft Ac + Silica Fumes) and (Soft Ac + Fly ash) respectively.

Keywords:

Asphalt concrete , repeated indirect tensile test , rutting , resilient modulus , recycling