A computational framework for mesoscale modelling of concrete with application to ballistic impact

Concrete is a multiphase composite material composed of high-strength aggregates, a cement matrix, and the interfacial transition zone (ITZ), whose inherent heterogeneity plays a critical role in its mechanical response. Phenomenological numerical models often assume a homogeneous material formulation, limiting their ability to capture localised failure mechanisms and the composite behaviour. This study presents a mesoscale modelling framework that explicitly represents concrete heterogeneity by incorporating aggregate distribution into finite element meshes generated from design-stage parameters. The approach is applied to ballistic impact scenarios and validated against previously published data by the authors. Finite elements simulations reproduced key experimental trends in stress-strain response, projectile residual velocity and mass loss. Furthermore, the heterogeneous formulation captured effects such as size-dependent behaviour, brittle-to-ductile transition and projectile rotation – which are not available using homogenised models. The framework is scalable and efficient, allowing for parametric studies on aggregate volume fraction, particle size distribution, and aggregate shape. This modelling approach may be used to optimise aggregate parameters during the design stage of a protective structure in response to a specified external threat. • Mesoscale model captured concrete heterogeneity using realistic aggregate geometry. • Framework reproduced size effects and brittle-to-ductile transition in concrete. • Simulations reflect experimental scatter in both material and ballistic tests. • Approach supports aggregate optimisation for protective structures.