This study evaluates the use of recycled concrete aggregate (RCA) in nonstructural concrete through laboratory
tests. Removed concrete bridges and slabs were selected from NCDOT bridge demolition and reconstruction
projects in NCDOT Divisions 1, 2, and 3 and was processed into coarse aggregates for Class B concrete as per the
2018 NCDOT Standard Specifications for Roads and Structures. The coarse RCA were undergone a series of
laboratory testing and used in concrete mixing. Engineering and cost analyses were performed based on the data collected from the survey, literature review and the results obtained from the laboratory testing.
The results show that the processed RCA from demolished bridges meet NCDOT requirements for concrete aggregates. The 7-day, 28-day, and 90-day compressive strength surpass the strength requirements for Class B concrete. From the laboratory test results, literature study, survey responses, technically there is no hindrance in using RCA in nonstructural concrete, and the concrete made using RCA in this study processes competitive properties to the concrete containing natural aggregates. The properties of RCA concrete could be modified by blending use of other recycled material(s). Concrete containing RCA and steel slag aggregates has higher compressive strength. A pioneer study was conducted during the project that provides directions of future research on blending use of RCA and other recycled materials in concrete.
The results will benefit the bridge and road construction projects specified in the State Transportation Implementation Plan. Eastern North Carolina will benefit by the comprehensive use recycled concrete aggregate through conservation of natural resource and balancing economic, environmental, and societal needs.
