AbstractMesoscale numerical modeling is an effective method of representing concrete as a three-phase material. Accurate aggregate geometry representation is an important aspect in numerical mesoscale modeling of concrete to predict mechanical properties as well as the damage initiation and fracture propagation. In this paper, a novel approach of three-dimensional (3D) scanning of aggregates using a structured light 3D scanner is presented, and parametric geometry reconstruction of aggregate geometries using spherical harmonics is carried out. This novel method of scanning aggregates is a faster, safer, economical, and convenient method of obtaining the 3D geometry compared with other methods. A comprehensive database of aggregate geometries is developed, and an innovative aggregate-placing algorithm for these aggregates is presented to develop the mesostructure. In addition to the proposed geometry generation method, a novel parametric-based geometry generation and distribution method for polyhedral aggregate shapes is presented, including flaky and elongated particles. Finally, aggregate transferring methods to finite-element software and mesh generation methods are discussed with the challenges and possible methods to overcome these issues.