A novel numerical algorithm for 2D and 3D modelling of recycled aggregate with different geometries

The establishment of an aggregate model that better matches real situations is one of the prerequisites to studying the mechanical properties of concrete. Previous models have focused on aggregates with regular shapes; however, this differs from the morphology of real aggregates, particularly recycled aggregate (RA). Due to the presence of adhered mortar, RA has more complex structural characteristics than natural aggregate (NA). It is therefore difficult to model RA, especially the distributions of irregular angles and sharp corners. A new modelling method based on the compression of circles and spheres is proposed in order to obtain circular, elliptical and convex polygonal aggregates in two-dimensional (2D) models and spherical, ellipsoidal and convex polyhedral aggregates in 3D models. The compression method has excellent scalability and applies to both NA and RA in both 2D and 3D models. Using the proposed compression modelling method, the aspect ratios, sharp corners, flakes, edges and needles of RA and NA can be characterised. Random aggregate models showed that the compression modelling method was able to construct 2D and 3D geometric models of concrete made with NA and RA with desirable aggregate distributions and aggregate morphological characteristics.