Dynamic Behavior of Layered 3D Printed Concrete Elements (2020-07)¶

Recently, the interest in digital fabrication techniques, such as 3D concrete printing, has grown at a dizzying speed, but at the same time many critical issues are still wide-open. Weak strength at the bond interface of two concrete layers, also referred as cold joint, is one such critical task to be scientifically investigated, especially in dependence on waiting time parameter between layers. It is a topic very structural engineering sensitive, because of the loss of instability and durability due to the occurrence of interface failure. The aim of this work is the study of the effect of interfaces on mechanical performance of 3D printed cementitious elements under dynamic loading conditions. In order to achieve this, an experimental campaign was performed on 3d printed concrete elements varying the time intervals between placements of subsequent layers, through high and medium strain rate tensile tests, using a Hydro-pneumatic machine and a Modified Hopkinson bar apparatus, respectively. The results exhibited a decrease in the dynamic interface tensile strength with the waiting time up to over 90% for a medium strain-rate of about 10 s−1 and over 20% for a high strain-rate.