Beneficial Use of Recycled Concrete Aggregate as Base and Subbase Material in Turkey

Recycled concrete aggregate (RCA), the main component of global construction and demolition (C&D) waste, is mostly stockpiled, creating environmental impacts, and consuming valuable land space. Utilizing RCA in geotechnical applications, particularly in highways would result in consumption of large volumes and decrease of the stockpiled amounts. In this study, the mechanical and hydraulic suitability of RCA as a base and/or subbase material was evaluated through a series of laboratory experiments. Proctor, CBR, permeability, and resilient modulus (RM) tests were performed to determine the compaction, strength, and hydraulic properties of the material. In addition, tests were also conducted on samples prepared on controlled grain size distributions that meet the American Association of State Highway and Transportation Officials (AASHTO) specifications as well as Turkey's General Directorate of Highways (KGM) Highway Technical Specification (KTS) upper and lower limits for base and subbase materials. The results indicate that the material used in this study is suitable for use as a base and/or subbase material, however the origin of the material substantially affects the characteristics of the material and prior to use of materials originating from different locations, strength, and hydraulic properties should be determined carefully.