Compaction mechanics of soft-rigid mixtures considering realistic particle morphology

Department of Civil Engineering, Indian Institute of Technology Madras, India

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Published online: 1 December 2025

Abstract

Soft-Rigid granular mixtures (SRM) demonstrate complex compaction behaviour due to the porefilling mechanism exhibited by the deformable particles. The current study provides a micro-mechanical perspective of the compaction behaviour of these soft-rigid granular mixtures (SRM- 30%, i.e., 30% deformable particles) and pure rigid assembly (SRM-0%, i.e., 0% deformable particles) having rigid realistic angular morphologies. The study first compares the variation of the void ratio during the gravity deposition over a range of inter-particle friction coefficients between zero and one. Furthermore, the study specifically focuses on understanding the evolution of pore size distribution during oedometer compression. A normal pressure at a quasi-static rate is applied on the granular assembly to achieve the 80% of densest volume fraction. The addition of soft deformable particles alters the compaction behaviour by specifically decreasing the void ratio more rapidly under minimal compaction effort, compared to a fully rigid particle assembly. The presence of deformable particles in the mixture enhances the pore filling mechanism which is quantified by computing the pore size distribution at two different stages of compaction. The post-compaction probability distribution of the pore radius infers that the smaller voids are drastically increased due to the addition of deformable particles.