Dynamic characterization of the layer-interface properties of 3D-printed concrete elements

Abstract

In this study, we used a Modified Hopkinson bar and a hydro-pneumatic machine to characterize the behaviour of 3D-printed concrete elements under different stress rates, focusing on the interface behaviour between consecutive layers under different loading conditions and in various significant, dynamic regimes. The paper includes the results of dynamic tensile tests and dynamic shear-tests at different stress rates (10−4 – 200 GPa/s) on 3D-printed cementitious elements for waiting times of 0.30 min, 10 min and 30 min in comparison with cast concrete elements. Dynamic increase factors (DIFs) versus stress rate curves for tensile and shear strength are also discussed. The shear-strength DIFs rise with the stress rate by up to 1.57 times compared to the quasi-static conditions at a waiting time of 30 min. Meanwhile, tensile tests reveal appreciable stress rate-sensitive behaviour, with an increase in the tensile-strength DIF of up to 7.6 for a high stress rate and at a waiting time of 30 min.