Modeling buildability in 3D concrete printing: A discontinuous Galerkin method with cohesive interfaces

Buildability, defined as the ability of a 3D concrete printed structure to sustain its own weight and maintain geometric stability, depends on both the evolving bulk material response and the integrity of interlayer bonds. Existing part-level simulation frameworks are typically based on continuous Galerkin formulations, which enforce displacement continuity across element boundaries and therefore cannot represent interlayer delamination. This paper presents a discontinuous Galerkin finite element method for simulating buildability in 3D concrete printing. The presented method captures both bulk plastic collapse and interlayer delamination in a unified framework. Interior facets are classified as either intra-layer or inter-layer. Intra-layer facets are coupled through symmetric interior penalty terms to recover bonded continuum behavior, whereas inter-layer facets are governed by a mixed-mode cohesive traction–separation law with structuration-dependent bond quality. The framework is further coupled to a time-dependent elasto-viscoplastic bulk model derived from rheological inputs and to a smooth element-activation scheme that represents progressive material deposition while maintaining a fixed computational mesh. The implementation is verified through six benchmark tests, demonstrating machine-precision accuracy where expected and optimal convergence for the full discretization. Validation against two experimental cases, a printed hollow cylinder failing by plastic collapse and a printed barrel vault failing by interlayer delamination, demonstrates that the dual-interface treatment activates the correct governing failure mode directly from the stress and damage fields, without a priori specification.