Compressive Behavior and Empirical Strength-Prediction Model for 3D-Printed Concrete

Abstract Design guidance for 3D-printed concrete (3DPC) is constrained by lack of a reliable method to estimate compressive capacity from conventional cast-cube results, particularly for hollow, shell-dominated elements typical of printed walls. This study addresses that gap using representative double-shell hollow cubes with controlled surface slopes (0°, 10°, 20°) to isolate shell load paths and texture-induced eccentricity. Under axial loading, the 0° specimens attained approximately 50% of the cast-cube strength, reflecting cavity-driven load redistribution and interlayer weakness. Introducing slopes further reduced capacity: at 28 days, 10° and 20° cases achieved roughly 37% and 33% of the cast control, respectively. Finite-element analyses corroborated a mechanism of load-path eccentricity, tensile hoop stress, and interface-localized damage near peaks. Based on the experimental matrix, we propose an empirical mapping from cast-cube strength to 3DPC capacity within the tested slope range; the relation provides intentionally conservative lower-bound estimates, underpredicting measured strengths by ∼ 12 % –19% at 14–28 days within the test domain. The findings clarify how hollow cores and surface slopes govern load paths and failure localization in printed shells and provide a practical estimator to support early-stage sizing, material screening, and conservative preliminary design of walls with hollow cores and textured surfaces without requiring full-scale tests under typical conditions.