Unconfined compressive behavior of column with geogrid-encased recycled aggregate: Test and simulation

Abstract

Geogrid-encased recycled aggregate column (ERAC) undergoes particle breakage during loading due to aggregates’ discreteness and brittleness, significantly affecting the engineering properties. To quantify particle breakage and investigate the shape effect on ERAC, this paper conducts five unconfined compression tests and discrete-continuum coupled numerical analyses on ERAC. Tests study the particle breakage, geogrid strain, and load-settlement response. Test results show that all relative particle breakage is less than 10% (maximum up to 9.02%), and only mass loss of less than 0.4% is noticed during loading. The relationship between the ultimate bearing capacity and relative breakage is established. From longest to smallest column, geogrid increases the bearing capacity by 40.59% with a 1.11% strain increment, and large diameter column has plastic strain exceeding 2%. Simulations study geogrid strain, coefficient of radial stress (Kps), particle displacement, contact force distribution, and porosity change. Simulation results show that the maximum overestimation in coefficient of passive earth pressure (Kp) used in the design is 21.7% compared with Kps value. A slight escaped particle in numerical simulation corresponds to a slight mass loss of less than 0.4% in the test. The contact force for Test-A, -B, and -C increases by 1176%, 4979%, and 1559% after loading. The porosity at Sphere A-1 increases by 55.33% due to volumetric expansion, particle movement, and settlement.