Strength and Deformation Characteristics of Recycled Concrete Aggregate in Triaxial Compression

To investigate the feasibility of the use of recycled concrete aggregate as the backfill material of geotechnical engineering structures, such as embankments, geo-synthetic reinforced soil retaining walls and bridge abutments, a series of drained triaxial compression tests were performed. Both axial and lateral strains were measured locally. It was found that the compressive strength, q_max, of recycled concrete aggregate highly compacted at water content in the vicinity of optimum moisture content, w_opt, becomes similar to that of well-graded gravel that has been used as the backfill material of highest quality. When compacted at w_opt, post-compaction saturation does not have any detrimental effect on q_max of recycled concrete aggregate. The viscous aspects of the stress-strain characteristics were evaluated. Upon the restart of MLfollowing each creep stage, t he specimen exhibited very stiff and nearly elastic response for some stress range followed by marked yielding. The changes in the stress ratio upon a stepwise change in the axial strain rate were rather proportional to the instantaneous stress ratio and the logarithm of the ratio of the strain rates after and before a step change. These trends are very similar to those of ordinary type backfill materials.