Recycled asphalt pavement (RAP) materials are an alternative tonatural aggregate (NA) because they reduce environmental pollutionand provide energy and cost savings. In many countries abroad, theusage of RAP materials in road pavement layers are permissible atcertain rates. However, the mechanical properties of RAP materials aredependent on; the materials are derived from the in which pavementlayer, the service life and construction characteristics of the road it ismilled, the properties of the materials used (bitumen and aggregate) inthe layer and the characteristics of the milling machine. In this study,two types of RAP materials ($RAP_1$ and $RAP_2$) obtained from thedegraded wearing layers of two different roadway using millingmachine were mixed with NA in different rates (0%, 15%, 30%, 45%,60%, 100%). Some of the characteristics of the mixtures were examinedwith reference to 100% NA mixture values by performing laboratorytests such as bitumen ratio, sieve analysis, modified proctor andCalifornia bearing ratio (CBR) on the mixtures obtained. According tothe results, maximum rates of $RAP_1$ and $RAP_2$ which can be used in plant mix base type-1 layer as an alternative material to NA is determinedaccording to Turkey Highway Technical Specification. In addition, in thecase of using RAP materials, the profit rates of material costs to bereduced by the reduction of the need for NA material are alsodetermined by cost analysis.