Geogrid-Aggregate Interlocking Mechanism Investigated via Discrete Element Modeling

Geogrids provide reinforcement for aggregate materials through interlocking between granular particles and geogrid apertures. The reinforcement or stabilization effect of a geogrid can be quite different when used with similar aggregate types but having different particle size distributions. This paper describes recent research efforts at the University of Illinois focused on triaxial compression testing of pavement base course aggregate materials having different gradations. An aggregate image-aided numerical modeling approach based on the Discrete Element Method (DEM) was adopted in this study with the capability to create actual aggregate particles as three-dimensional polyhedron elements. The DEM simulations of aggregate assemblies then had the same grain size distributions and the imaging quantified average aggregate shapes and angularities. Cylindrical triaxial test specimens were simulated at two different gradations to investigate the geogrid-aggregate interlocking mechanism and how reinforcement benefits could be maximized. With higher coordination number, and therefore higher number of contacts between geogrid and aggregate particles, the specimen had a better packing structure, which yielded higher strength properties from the triaxial compression test.