EVALUATION OF LONG-TERM BEHAVIOR OF COLD RECYCLED ASPHALT MIXTURE.

The technique of recyclng asphalt pavement materials has been widely used in the past decade, but unsolved problems such as rutting and instability still exist. Softening agents or low-viscosity binders such as emulsified asphalts are usually added during the cold recyling process, which may have slow softening reaction. Thus, the properties of the recycled mixtures are controlled by several factors, including the oxidation hardening of the new bituminous materials and the softening effect of the softening agents or emulsions. An evaluation of the long-term behavior of such mixtures by means of both creep and Marshall tests conducted at 75 degree F is presented. The mixture was artifically aged by curing at 140 degree F up to 60 days and tested at different ages. The creep compliance of both virgin and recycled mixtures decreased rapidly at early ages due to the oxidation of the asphalt binder and then remained essentially the same.