The Friction And Dilatancy Angle Of Recycled Concrete Aggregate

Recycled Concrete Aggregate (RCA) is a construction and demolition material, which in unbound state can be placed as subbase in road structures. Over last decades there was many investigations which highlighted physical and mechanical properties of this material. Nevertheless, successful application of RCA still needs more tests. For sustainable development of road engineering, utilization of recycled material is essential. In this article direct shear tests were performed to characterize mechanical properties of RCA. Direct shear tests were conducted with and without modification by adding metal frames to shear cubic shaped box with length of side equal 250mm. Material used in this paper was RCA in gradation with lead to recognize it as sandy gravel. Tests were performed for various moisture content material compacted with to respect of normal energy in Proctor method. Tests shows differences between direct shear with and without metal frames. For RCA tested in standard test conditions friction angle differs between 32.4 degrees to 65.1 degrees. Modification of test equipment results in friction angle equal 38.7 degrees to 41.5 degrees. Both tests indicated impact of moisture conditions during compaction. In this study, dilation angle analysis was also performed. Dilation angle values were in range from 5 degrees to 10 degrees. Brittle nature of RCA results in low value of the dilatancy index.