Meso-structure study of recycled aggregate stabilized by multi-source solid waste geopolymer based on discrete element method
Abstract
To reveal the meso-mechanism of the axial compression failure of recycled aggregates stabilized by multi-source solid waste geopolymers and to overcome the limitation that traditional laboratory tests cannot observe the meso-state of the material, a three-dimensional numerical model of this material was established using PFC3D discrete element software to simulate an unconfined compressive strength test. The meso-contact parameters for the specific mix proportion were calibrated using the back-analysis method. The stress–strain curves obtained from the simulation and laboratory tests were compared and analyzed. The meso-rules of axial compression deformation and failure of the material were analyzed from the perspectives of crack evolution, particle movement, and force chain transmission. The results show that the descending branch and failure mode of the stress–strain curves from the discrete element simulation are highly consistent with those from laboratory tests, whereas slight differences exist in the ascending branch owing to model limitations and material randomness. The through-cracks of the specimen failure are mainly distributed in the middle and lower parts. The cracks initiate from the middle of both sides and propagate longitudinally. The increase in cementation bond breakage reached 349.5% during the rapid crack development stage. After failure, the particles in the middle and lower parts of the specimen flowed around, and the particles in the upper part moved downward slowly. The force chains were uniformly distributed in the elastic stage. However, a large number of force chains broke, and the high-force chains were concentrated in the middle and lower parts in the crack development stage. This study verifies the feasibility of the discrete element method in simulating the meso-mechanical behavior of this material and provides a meso-theoretical basis for its mix ratio optimization and engineering applications.