Effect of using recycling pavement on untreated aggregate base course properties

The supplies of natural materials used III constructing newpavements are reduced and disposal of the old pavement materials is anenvironmental problem. Thus the old materials must be recycled.This study concerned with studying the possibility of reusing the oldasphaltic surface course from flexible pavement (asphalt granulate) inconstructing untreated base course. To study this possibility, the behaviorof base course materials using asphalt granulate with different percentagesmixed with each crushed limestone and sandy gravel is investigated. Theeffect of adding asphalt granulate to the mixture on maximum dry density,optimum water content, impact, wear, unsoaked and soaked C.B.R at, erent compaction energies are also studied.Results indicate that, increasing the percentage of asphalt granulatein the mixture decreases the maximum dry density, optimum water content,unsoaked and soaked C,B.R. and abrasion resistance but increases impactresistance. It can be concluded that the asphalt granulate can be reused inOODltructin’: g the untreated base course under certain conditions.