Predication of Strength-Based Failure in Extrusion-Based 3D Concrete Printing

Extrusion-based concrete 3D printing is an emerging construction technique to build the desired structure layer by layer without using any type of formwork. Hence, the printable concrete requires to achieve adequate strength to support the self-weight and subsequent layers in short period of time. This paper aims to identify the strength-based failure limits of 3D printing concrete through experimental and numerical procedure. The 3D Printing experiments were carried out to obtain the height of failure (i.e., number of printed layers before failure). The important rheological parameters of 3D printable concrete mixes were estimated experimentally and used in a numerical simulation as well as in theoretical equations to compare the results. The strength-based failure criterion for 3D printed object was developed and validated numerically using FLAC 3D (i.e., Fast Lagrangian Analysis of Continua). The time-dependent material behaviour was considered in the numerical analysis and the failure mode and the failure heights were modelled and compared with the experimental values. It was found that the experimental results and the numerical simulation results are comparable and the numerical simulation can be used as a reliable tool to decide the rheological parameters of 3D printing concrete for preventing the strength based failure.