Overlay and maintenance resolve medium distress, but reconstruction may feasible and economical while Asphalt pavement are badly deteriorated with time and traffic. This requires the removal of existing pavement surfaces. Recycling such construction waste has benefited from economic to sustainability point of view and reduce the exploitation of natural resources. The shortage of virgin aggregate supplies along with the increase in processing and hauling cost have encouraged the use of reclaimed material from the old structure as base course construction materials, and involved in regular practice in various countries around the world. Unfortunately, using Reclaimed asphalt pavement (RAP) is to take off in Ethiopia despite the current ambitions of road building program ongoing. However, RAP material may be not conventional road making materials and need for improvement. This study was aimed to investigation the Engineering properties effect of using RAPs and CSA in their natural state by conducting common laboratory tests in first phase, and Second phase of the study was intended to analysis the strength and interpret the optimum allowable percentage as partial replacement of CSA wjert, 2018, Vol. 4, Issue 2, 126-167.